Dielectric filter

Description

[0001] This invention relates to a dielectric band elimination filter. More particularly, this invention relates to a dielectric band elimination filter adapted for use in a mobile communication apparatus such as a portable telephone.

[0002] As shown in Fig. 25, and also by an equivalent circuit diagram shown in Fig. 26, a prior art single-stage dielectric band elimination filter (BEF) is formed with a dielectric resonator 111 and a coupling capacitor C_e 112 connected in series through a connector terminal 113. Its frequency-attenuation characteristic is shown in Fig. 27. Fig. 28 is a block diagram of a prior art mobile communication apparatus such as a portable telephone, and a dielectric band elimination filter, as described above, is used in the transmitter circuit inside its duplexer D₁. The transmitter frequency f_TX and the receiver frequency f_RX of this communication apparatus are indicated in the diagram of Fig. 27. It is adjusted such that the receiver frequency f_RX and the trap frequency f_T of the dielectric BEF match each other.

[0003] As another example of prior art technology, a general prior art two-stage dielectric BEF is shown in Fig. 29. In Fig. 29, and Fig. 30 which is its equivalent circuit diagram, R indicates a resonator, C_e indicates a trap capacitor, C_t indicates a parallel capacitor, L indicates an inductor serving as a quarter-wavelength phase shifter, and numerals 121, 122, 123, 124 respectively indicate a case cover, a connector terminal, an inductor pattern substrate, and a common substrate. Fig. 31 shows the frequency-attenuation characteristic of this dielectric BEF, and also indicates the transmitter frequency f_TX and the receiver frequency f_RX when this filter is used in the transmitter side of the duplexer D₁ of the communication apparatus shown in Fig. 28. In this application, too, the receiver frequency f_RX and the trap frequency f_T of the filter are adjusted to match each other.

[0004] With prior art mobile communication apparatus as described above, waves with frequency f_s = f_TX - (f_RX - f_TX) entering from the antenna A₁ into the transmitter side of the duplexer D₁ cannot be stopped by a dielectric BEF with attenuation characteristic as given in Fig. 27 or Fig. 31 alone. This is why an isolator I₁ is inserted into the transmitter circuit. In addition, a band pass filter (BPF) B₁ is required in the transmitter circuit in order to attenuate waves with unwanted frequencies generated in the mixer M₁ on the transmitter side.

[0005] Problems of this kind would not occur if a dielectric BPF were used in the place of the dielectric BEF in the transmitter circuit of the duplexer D₁, but there would arise a different problem that insertion loss and attenuation characteristics obtainable by a dielectric BEF cannot be fully realized by a filter of a comparable size. In order to form a single-stage dielectric BEF as described above, furthermore, not only a dielectric resonator but also a coupling capacitor and a connector terminal for connecting the dielectric resonator and the coupling capacitor would be needed. Similarly, in order to form a two-stage dielectric BEF as described above, not only a dielectric resonator but also extra component parts such as a case cover, connector terminals, an inductor pattern substrate and a common substrate would be needed. In short, the number of required component parts and cost would increase, and the apparatus would become bulkier.

[0006] It is therefore an object of this invention to eliminate the problems described above and to provide dielectric BEFs which are capable of simplifying the circuit structure of mobile communication apparatus such as portable telephones, having only a small number of component parts and being compact in size.
dielectric band elimination filter comprising:

[0007] A small interdigital filter is disclosed in JP-A-61-167201 having plural cylindrical metallised throughholes in a dielectric block having a conductive film thereon. One end of each hole has a non-conductive portion provided on the surface of the dielectric block. Adjacent conductive through-holes have their non-conductive portion at opposite ends.

[0008] The invention provides a dielectric band elimination filter comprising a dielectric block having outer surfaces including two mutually opposite first and second end surfaces; an outer conductor covering portions of said outer surfaces; and two mutually coupled resonant lines formed extending in said dielectric block between said end surfaces, each of said resonant lines having an open end which is not in contact with said outer conductor and a shorted end which is in contact with said outer conductor, said open and shorted ends of said two resonant lines are oppositely oriented; characterised in that said open end of one of said two resonant lines is unconnected to an outer circuit and said open end of said other of said resonant lines is connected to an outside circuit.

[0009] The invention also provides a dielectric band elimination filter as above, wherein said dielectric block has a plurality of single-stage band elimination filters each having two interdigitally coupled resonant lines extending between said first and second end surfaces inside throughholes through said block, each mutually adjacent pair of said single-stage band elimination filters being interdigitally coupled or combline-coupled to each other with phase shift of π/2.

[0010] Each single-stage band elimination filter may be structured as described above, each of its two resonant lines having an open end and a shorted end, and their open and shorted ends being oriented oppositely. Each open end may be formed at one of the end surfaces of the dielectric block, being connected to an electrode on the end surface and insulated from the outer conductor, or at an annular conductor-free area formed on the inner surface of the corresponding throughhole.

[0011] The resonant lines for forming the plurality of single-stage band elimination filters may be arranged in various ways. They may be arranged in two horizontal rows (the upper and lower rows) and many vertical columns, those one the upper and lower rows in each column forming a single-stage filter. With this arrangement of the resonant lines, all of the resonant lines on the upper row may be arranged to have their open ends pointing towards one of the end surfaces of the dielectric block, those on the lower row pointing to the other end surface. Alternatively, the resonant lines may be so arranged that the open ends of two mutually adjacent resonant lines on the same row are always oriented in opposite directions. Screening electrodes may be inserted between resonant lines which are next to each other on the same row.

[0012] The pairs of resonant lines forming single-stage band elimination filters need not all be arranged in the same direction. Two such filters with horizontally arranged resonant line may sandwich one with vertically arranged resonant line inside a horizontally elongated dielectric block with an upwardly protruding center part for forming therein one of the resonant lines for the vertically arranged filter.

[0013] The throughholes for containing the resonant lines may have a flattened shape such that the dielectric block can be made thinner.

Brief Description of the Drawings

[0014] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

Fig. 1 is a schematic diagonal view of a single-stage dielectric BEF according to a first embodiment of this invention;

Fig. 2 is a circuit structure diagram of the filter of Fig. 1;

Fig. 3 is an equivalent circuit diagram of the filter of Fig. 1;

Fig. 4 is a sectional view of the filter of Fig. 1 taken along line 4-4 in Fig. 1 for explaining equivalent capacitors;

Fig. 5 is a diagram showing the input impedance characteristic of the filter of Fig. 1;

Fig. 6 is a frequency-attenuation characteristic of the filter of Fig. 1;

Fig. 7 is a schematic diagonal view of another single-stage dielectric BEF according to a second embodiment of this invention;

Fig. 8 is a schematic diagonal view of still another single-stage dielectric BEF according to a third embodiment of this invention;

Fig. 9 is a schematic diagonal view of a two-stage dielectric BEF according to a fourth embodiment of this invention;

Fig. 10 is a circuit structure diagram of the filter of Fig. 9;

Fig. 11 is an equivalent circuit diagram of the filter of Fig. 9;

Fig. 12 is a frequency-attenuation characteristic diagram for the filter of Fig. 9 and a prior art filter;

Fig. 13 is a schematic diagonal view of a five-stage dielectric BEF according to a fifth embodiment of this invention;

Fig. 14 is an equivalent circuit diagram of the filter of Fig. 13;

Fig. 15 is a schematic diagonal view of another five-stage dielectric BEF according to a sixth embodiment of this invention;

Fig. 16 is an equivalent circuit diagram of the filter of Fig. 15;

Fig. 17 is a schematic diagonal view of still another five-stage dielectric BEF according to a seventh embodiment of this invention;

Fig. 18 is a schematic diagonal view of a three-stage dielectric BEF according to an eighth embodiment of this invention;

Fig. 19 is a circuit structure diagram of the filter of Fig. 18;

Fig. 20 is an equivalent circuit diagram of the filter of Fig. 18;

Fig. 21 is a schematic diagonal view of another three-stage dielectric BEF according to a ninth embodiment of this invention;

Fig. 22 is a schematic diagonal view of still another three-stage dielectric BEF according to a tenth embodiment of this invention;

Fig. 23 is a schematic diagonal view of a six-stage dielectric BEF according to an eleventh embodiment of this invention;

Fig. 24 is a schematic diagonal view of a three-stage dielectric BEF according to a variation of the tenth embodiment of this invention;

Fig. 25 is an exploded diagonal view of a prior art single-stage dielectric BEF;

Fig. 26 is a circuit structure diagram of the prior art filter of Fig. 25;

Fig. 27 is a frequency-attenuation characteristic diagram of the prior art filter of Fig. 25;

Fig. 28 is a block circuit diagram of a mobile communication apparatus such as a portable telephone, using a prior art dielectric BEF;

Fig. 29 is an exploded diagonal view of another prior art dielectric BEF;

Fig. 30 is a circuit structure diagram of a general prior art dielectric filter; and

Fig. 31 is a frequency-attenuation characteristic diagram of the prior art filter of Fig. 29.

[0015] Fig. 1 shows a single-stage dielectric BEF according to a first embodiment of this invention, formed by a combination of two resonant lines. A rectangular dielectric block 101 has two circular cylindrical throughholes 102a, 103a formed near each other from one end surface to the opposite end surface. Inner conductors are formed on the inner surfaces of the throughholes 102a, 103a. The inner conductor inside throughhole 102a is connected to a rectangular electrode 102b on one of the end surfaces (first end surface) of the dielectric block 101. The inner conductor inside throughhole 103a is connected to another rectangular electrode 103b on the other end surface (second end surface) of the dielectric block 101. The outer surfaces of the dielectric block 101 are substantially entirely covered by an outer conductor, excluding conductor-free (or dielectric-exposing) areas 102c, 103c surrounding the electrodes 102b, 103b. The inner conductor inside throughhole 102a is connected to the outer conductor on the second end surface of the dielectric block 101 to form a quarter-wavelength resonant line 102. The inner conductor inside through- hole 103a is connected to the outer conductor on the first end surface of the dielectric block 101 to form another quarter-wavelength resonant line 103. The conductor-free areas 102c, 103c serve as open ends of these quarter-wavelength resonant lines 102, 103. It is to be noted that these two resonant lines 102, 103 are in a point-symmetric relationship with respect to the centre of the dielectric block 101.

[0016] Fig. 2 shows the circuit structure of the filter described above, its equivalent circuit diagram being shown in Fig. 3, and Fig. 4 is a sectional view of the filter taken along line 4-4 in Fig. 1 to show how equivalent capacitors are formed. As indicated in Fig. 4, self-capacitance C₁₁ per unit length is formed between each of the resonant lines 102, 103 and the outer conductor, and mutual capacitance C₁₂ is formed between the two resonant lines 101, 103. In Figs. 2 and 3, Z_in indicates the input impedance. In Fig. 3, Z_e and Z_o, respectively indicate the even-mode and odd-mode characteristic impedance give by:



where ε_r is the specific dielectric constant and V_c is the speed of light. The coupling characteristic impedance Z_k is defined as:

The phase angle θ is given by:

where ω indicates the angular frequency (or ω = 2Πf where f is the frequency), and L indicates the length of each resonant line.

[0017] In Fig. 3, the equivalent circuit diagram shows a parallel connection of the even-mode characteristic impedance Z_e and a series connection of the coupling characteristic impedance Z_k and the even-mode characteristic impedance Z_e between the input (output) and the ground.

[0018] Fig. 5 shows the input impedance characteristic of this filter, and Fig. 6 shows its frequency-attenuation characteristic. In Fig. 6, the trap frequency f_T is given by:

In Fig. 6, the solid line is for this invention; the broken line is for a prior art example shown in Fig. 27. Fig. 6 shows that increased attenuation is obtained by the present invention both in regions (indicated by double-headed arrows) on the higher frequency and lower frequency sides of the trap frequency.

[0019] If a single-stage dielectric BEF according to this invention having such a frequency-attenuation characteristic is used in the transmitter circuit of the duplexer D₁ of the mobile communication apparatus shown in Fig. 28, it becomes possible to eliminate the isolator I₁ for stopping invading waves from the antenna A₁ into the transmitter side of the duplexer D₁ because sufficient attenuation is obtained on the lower frequency side of the trap frequency. Since attenuation is obtained both on the lower and higher frequency sides of the trap frequency, furthermore, the BPF B₁ for attenuating waves with unwanted frequencies generated by the mixer M₁ on the transmitter side can be either eliminated or replaced by a smaller, less costly BPF with fewer stages. Moreover, since the dielectric BEF according to this invention is formed with a single dielectric block providing its trap circuit by a mutually coupling pair of resonant lines, there is no need for a coupling capacitor to be connected or any connector terminal. In other words, the number of component parts can be reduced.

[0020] Fig. 7 shows another single-stage dielectric BEF according to a second embodiment of this invention, which is similar to the one described above except that the electrodes 103b for resonant line 103 and the outer conductor are removed from the second end surface. Components which are substantially identical or function substantially identically to those of the filter shown in Fig. 1 are indicated by the same numerals and are not repetitively described below.

[0021] The filter according to the second embodiment shown in Fig. 7 functions substantially like the first embodiment and is advantageous in that the number of electrode patterns is reduced and hence that it can be produced at a reduced cost.

[0022] Fig. 8 shows still another single-stage dielectric BEF according to a third embodiment of this invention, which is similar to the first embodiment described above with reference to Fig. 1 and of which components substantially identical or at least similar to those of the first embodiment are indicated in Fig. 8 by the same numerals. The third embodiment is different from the first embodiment in that two inner conductors (first and second inner conductors) are formed inside one of the throughholes (104a). One end of the first inner conductor is connected to the outer conductor on the first end surface of the dielectric block 101. One end of the second inner conductor is connected to the outer conductor on the second end surface of the dielectric block 101. Between the other ends of the two inner conductors, there is an annular conductor-free (or dielectric-exposing) area 104b formed on the inner surface of the throughhole 104a near the second end surface. The longer one of the inner conductors (or the first inner conductor in Fig. 8) serves as the resonant line 104, having its open end inside the throughhole 103a.

[0023] Although not separately illustrated in a figure, the conductor-free area 104b may be formed adjacent to the second end surface (there being no second inner conductor), as a variation of the third embodiment.

[0024] A single-stage filter according to the third embodiment of the invention also has functions similar to the first embodiment and is advantageous wherein it has better shielding effects because the outer surfaces of the dielectric block 1 are completely covered by the outer conductor except at the input and output portions.

[0025] Fig. 9 shows a two-stage dielectric BEF according to a fourth embodiment of this invention, comprising a rectangular dielectric block 10 having four circular cylindrical throughholes 1a, 2a, 3a, 4a formed therethrough near one another from one end surface to the opposite end surface of the block 10. Inner conductors are formed on the inner surfaces of the throughholes 1a, 2a, 3a, 4a. The inner conductor inside throughhole 2a is connected to an electrode 2b on one of the end surfaces (first end surface) of the block 10. The inner conductor inside throughhole 3a is connected to another electrode 3b on the other end surface (second end surface) of the block 10. The outer surfaces of the block 10 are substantially entirely covered by an outer conductor except conductor-free (or dielectric-exposing) areas 2c, 3c surrounding the electrodes 2b, 3b.

[0026] Inside throughhole 1a, an annular conductor-free (or dielectric-exposing) area 1c is formed on the inner surface near the second end surface. Inside throughhole 4a, another annular conductor-free (or dielectric-exposing) area 4c is formed on the inner surface near the first end surface. The inner conductors inside throughholes 1a, 3a, 4a are connected to the outer conductor on the first end surface, and the inner conductors inside throughholes 1a, 2a, 4a are connected to the outer conductor on the second end surface such that interdigital resonator lines 1-4 are formed by these throughholes 1a-4a. It is to be noted that the conductor-free areas 1c, 2c, 3c, 4c serve as open ends of the resonant lines 1-4.

[0027] Although not separately illustrated in figures, the annular conductor-free areas 1c, 4c may be formed adjacent respectively to the second end surface and to the first end surface of the block 10, as discussed with reference to the filter according to the third embodiment of the invention shown in Fig. 8.

[0028] As shown in Fig. 10, which is a circuit structure diagram of the filter shown in Fig. 9, resonant lines 1, 2 couple to each other interdigitally to together form a one-stage BEF 11, and resonant lines 3, 4 similarly couple to each other interdigitally to together form another single-stage BEF 12. These two BEFs 11, 12 are coupled to each other through a quarter-wavelength phase shifter formed between the resonant lines 2, 3 such that a two-stage dielectric BEF is formed as a whole. A dielectric BEF thus formed is capable of providing attenuation on both higher and lower frequency sides of the trap frequency, the electrodes 2b, 3b of the resonant lines 2, 3 serving as input and output lines. In Fig. 11, which is an equivalent circuit diagram of the filter of Fig. 9, Z_e, Z_k and θ again indicate the even-mode characteristic impedance, coupling characteristic impedance and phase shift angle of Π/2, respectively. Each single-stage BEF 11, 12 is represented as a parallel connection of a series-connected parallel branch comprising (Z_k, θ) and (Z_e, θ) and another parallel branch comprising (Z_e, θ). The filter shown in Fig. 9 is represented as a combination of two such single-stage BEFs connected through transmission lines (Z_k, θ).

[0029] In the frequency-attenuation characteristic diagram of Fig. 12, the solid line is for the filter described above, the broken line is for a prior art filter represented by Fig. 31. Fig. 12 shows that attenuation at the trap frequency f_T is approximately the same but that increased attenuation is obtained by the present invention both on lower and higher frequency regions (shown by arrows) with respect to the trap frequency f_T.

[0030] In the prior art example shown in Fig. 29, an LC-type Π-circuit is adapted to serve both as a quarter-wavelength phase shifter and a low pass filter for obtaining attenuation outside the band. With an LC-type low pass filter, however, attenuation cannot be obtained on the lower frequency side, and attenuation on the higher frequency side is not sufficiently great, as compared to what is achievable by the present invention.

[0031] If a two-stage dielectric BEF having such frequency-attenuation characteristic is used in the transmitter circuit in the duplexer D₁ of the mobile communication apparatus shown in Fig. 28, it is possible to eliminate the isolator I₁ for stopping invading waves from the antenna A₁ into the transmitter side of the duplexer D₁ because sufficient attenuation is obtained on the lower frequency side of the trap frequency. Since attenuation is obtained in fact both on the lower and higher frequency sides of the trap frequency, the BPF B₁ for attenuating waves of unwanted frequencies generated by the mixer M₁ on the transmitter side can be either eliminated or replaced by a smaller, less costly BPF with fewer stages.

[0032] Fig. 13 shows a five-stage combline-coupled dielectric BEF according to a fifth embodiment of this invention, comprising a rectangular dielectric block 20 having a total of ten circular cylindrical throughholes formed therethrough near one another from one end surface to the opposite end surface of the block 20, arranged geometrically in two horizontal rows such that resonant lines 21a-25a are formed in the five throughholes of the upper row and resonant lines 21b-25b are formed in the five throughholes of the lower row.

[0033] On one of the end surfaces (first end surface) of the dielectric block 20, the resonant lines 21a-25a of the upper row each have a shorted end and the resonant lines 21b-25b of the lower row each have an open end. On the opposite end surface (second end surface) of the block 20, the resonant lines 21a-25a of the upper row each have an open end and the resonant lines 21b-25b of the lower row each have a shorted end. The outer surfaces of the dielectric block 20 are substantially entirely covered by an outer conductor excluding the open end surfaces. Inner conductors are formed on the inner surfaces of the throughholes forming the resonant lines 21a-25a, 21b-25b.

[0034] Each of pairs of upper-row and lower-row resonant lines 21a with 21b, 22a with 22b, 23a with 23b, 24a with 24b, 25a with 25b couples interdigitally to form one-stage BEFs 21, 22, 23, 24, 25. Each mutually adjacent pair of these one-stage BEFs is combline-coupled to each other according to a known mechanism. Input to and output from this dielectric filter are effected through the resonant lines 21b and 25b. An equivalent circuit diagram of this filter is shown in Fig. 14, showing single-stage BPFs, each represented as a parallel connection of a series-connected branch with (Z_e, θ) and (Z_k, θ) and another branch (Z_e, θ), connected through shorted transmission lines (Z_k, θ).

[0035] Fig. 15 shows a five-stage interdigitally coupled dielectric BEF according to a sixth embodiment of this invention, comprising a rectangular dielectric block 30 having a total of ten circular cylindrical throughholes formed therethrough near one another from one end surface to the opposite end surface of the block 30, arranged geometrically in two horizontal rows, resonant lines 31a-35a being formed in the five throughholes of the upper row and resonant lines 31b-35b being formed in the five throughholes of the lower row. Inner conductors are formed on the inner surfaces of these ten throughholes for the resonant lines 31a-35a, 31b-35b.

[0036] Resonant lines 31a, 32b, 33a, 34b, 35a each have a shorted end on one of the end surfaces (first end surface) of the dielectric block 30 and an open end on the other end surface (second end surface). Resonant lines 31b, 32a, 33b, 34a, 35b each have an open end on the first end surface and a shorted end on the second end surface. The outer surfaces of the dielectric block 30 are substantially entirely covered by an outer conductor except at the aforementioned open ends. Each of the pairs of upper and lower resonant lines 31a with 31b, 32a with 32b, 33a with 33b, 34a with 34b, 35a with 35b couples to each other interdigitally to form a single-stage BEF 31, 32, 33, 34, 35. Each mutually adjacent pair of these one-stage BEFs is interdigitally coupled, as shown in the equivalent circuit diagram of Fig. 16. Since this equivalent circuit diagram is similar to the one explained above in Fig. 11, it is not repetitively explained here. Input to and output from this filter are effected through resonant lines 31b and 35b.

[0037] Fig. 17 shows another five-stage combline-coupled dielectric BEF according to a seventh embodiment of this invention. This filter is similar to the one described above with reference to Fig. 13 except that screening electrodes 41 connected to the outer conductor are provided between each mutually adjacent pair of the resonant lines 21a-25a of the upper row. In all other aspects, this filter is identical to the one shown in Fig. 13. Therefore, same numerals as used in Fig. 13 are used in Fig. 17 to indicate identical components.

[0038] Fig. 18 shows a three-stage interdigitally coupled dielectric BEF according to an eighth embodiment of this invention, comprising a rectangular dielectric block 50 having a total of six circular cylindrical throughholes formed therethrough near one another from one end surface to the opposite end surface of the block 50, arranged geometrically in two horizontal rows, resonant lines 51a-53a being formed in the throughholes of the upper row and resonant lines 51b-53b being formed in the throughholes of the lower row. Inner conductors are formed on the inner surfaces of these throughholes for the resonant lines 51a-53a, 51b-53b. The inner conductors of the resonant lines 51b, 52a, 53b are connected respectively to electrodes 51c, 52c, 53c on one of the end surfaces (first end surface) of the block 50 and to an outer conductor on the other end surface (second end surface). The inner conductors of the resonant lines 51a, 52b, 53a are connected respectively to electrodes 51d, 52d, 53d on the second end surface and to the outer conductor on the first end surface. The outer conductor covers the outer surfaces of the dielectric block 50 substantially entirely except conductor-free (or dielectric-exposing) areas 50a surrounding the electrodes 51c-53c, 51d-53d.

[0039] Screening electrodes 54 are provided between horizontally adjacent pairs of resonant lines of the upper row 51a with 52a, 52a with 53a for preventing coupling therebetween. Each pair of vertically adjacent resonant lines 51a with 51b, 52a with 53b, 53a with 53b of the upper and lower rows is interdigitally coupled to form single-stage BEFs 51, 52, 53. Mutually adjacent pairs of the resonant lines of the lower row 51b with 52b, 52b with 53b are interdigitally coupled with phase shift of Π/2 such that the three single-stage BEFs 51, 52, 53 together form an interdigitally coupled dielectric BEF. Fig. 19 is its circuit structure diagram, and Fig. 20 is its equivalent circuit diagram.

[0040] Fig. 21 shows another three-stage interdigitally coupled dielectric BEF according to a ninth embodiment of this invention, comprising a rectangular dielectric block 60 having a protrusion and a total of six throughholes formed therethrough with inner conductors formed on the inner surfaces of these throughholes so as to provide six resonant lines 61a-63a, 61b-63b near one another. Resonant lines 62a and 62b are vertically adjacent to each other and interdigitally coupled to each other to together form a single-stage BEF 62. Pairs of resonant lines 61a with 61b, 63a with 63b are horizontally adjacent and interdigitally coupled to each other to form single-stage BEFs 61 and 63, respectively. The inner conductors of the resonant lines 61b, 62a, 63a are connected respectively to electrodes 61c, 62c, 63c on one end surface (first end surface) of the dielectric block 60 and to an outer conductor on the opposite end surface (second end surface). The inner conductors of resonant lines 61a, 62b, 63b are connected respectively to electrodes 61d, 62d, 63d on the second end surface and to the outer conductor on the first end surface. The outer conductor covers the outer surfaces of the dielectric block 60 substantially entirely except at conductor-free (or dielectric-exposing) areas 60a around the electrodes 61c-63c, 61d-63d. The three single-stage BEFs 61, 62, 63 are interdigitally coupled with phase shift of Π/2 as in the preceding embodiment of the invention, forming an interdigitally coupled dielectric BEF. The circuit structure diagram and the equivalent circuit diagram of this filter are substantially the same as shown in Figs. 19 and 20.

[0041] Fig. 22 shows still another three-stage interdigitally coupled dielectric BEF according to a tenth embodiment of this invention, comprising a rectangular dielectric block 70 having a total of six resonator-forming throughholes formed therethrough from one end surface to the opposite end surface of the block 70, arranged geometrically near one another so as to provide three circular cylindrical resonant lines 71a-73a on an upper row and three others 71b-73b on an lower row. Inner conductors are formed on the inner surfaces of these resonator-forming throughholes.

[0042] The inner conductors of the resonant lines 71b, 73b are respectively connected to electrodes 71c, 73c on one of the end surfaces (first end surface) of the dielectric block 70. Both ends of the inner conductors of the resonant lines 71a-73a, 71b-73b are connected to an outer conductor except at the ends of the resonant lines 71b, 73b on the first end surface. The outer conductor covers the outer surfaces of the dielectric block 70 substantially entirely except at conductor-free (or dielectric-exposing) areas 70a surrounding the electrodes 71c, 73c.

[0043] The resonant lines 71a, 72b, 73a are respectively provided with annular conductor-free (or dielectric-exposing) areas 71d, 72d, 73d near the opposite end surface (second end surface) of the dielectric block 70. The resonant line 72a is similarly provided with an annular conductor-free (or dielectric-exposing) area 72c near the first end surface of the dielectric block 70. These annular areas 71d-73d, 72c serve not only to divide the corresponding inner conductors into two parts but also as open ends of the corresponding resonant lines. Although not separately illustrated, these annular areas 71d-73d, 72c may each be formed adjacent to (rather than near) the first or second end surface.

[0044] Screening throughholes 70b are formed through the dielectric block 70 parallel to the aforementioned resonator-forming throughholes between the resonant lines 71a and 72a and also between the resonant lines 72a and 73a on the upper row. These screening throughholes 70b contain screening electrodes therein, in contact with the outer conductor at both ends so as to prevent coupling between the resonant lines 71a and 72a and between the resonant lines 72a and 73a. The vertically adjacent pairs of resonant lines 71a with 71b, 72a with 72b, 73a with 73b are interdigitally coupled to each other to form three single-stage BEFs 71, 72, 73. The mutually adjacent pairs of resonant lines on the lower row 71b with 72b, 72b with 73b are each interdigitally coupled with phase shift of Π/2 such that the three single-stage BEFs 71, 72, 73 together form an interdigitally coupled dielectric BEF. Fig. 19 shows its circuit structure diagram, and Fig. 20 shows its equivalent circuit diagram.

[0045] Fig. 23 shows a six-stage interdigitally coupled BEF according to an eleventh embodiment of this invention, comprising a rectangular dielectric block 80 having a total of twelve circular cylindrical throughholes formed from one end surface to the opposite end surface of the dielectric block 80, geometrically arranged in three horizontal rows and four vertical columns, having inner conductors formed on the inner surfaces of the throughholes so as to serve as resonant lines 81a-86a, 81b-86b. Resonant lines 81a, 82b, 83a, 84a, 85b, 86a each have an open end on one of the end surfaces (first end surface) of the dielectric block 80 and a shorted end on the opposite end surface (second end surface) of the dielectric block 80. Resonant lines 81b, 82a, 83b, 84b, 85a, 86b each have a shorted end on the first end surface and an open end on the second end surface. The outer surfaces of the dielectric block 80 are substantially entirely covered by an outer conductor except at the aforementioned open ends. Screening electrodes 80a connected to the outer conductor are provided between mutually adjacent pair of resonant lines 81b and 86a of the lower row and between mutually adjacent pair of resonant lines 82b and 85a of the middle row. Horizontally adjacent pairs of resonant lines 81a and 81b, 82a and 82b, 83a and 83b, 84a and 84b, 85a and 85b, 86a and 86b couple to each other interdigitally within themselves to form single-stage BEFs 81, 82, 83, 84, 85, 86, respectively. Mutually adjacent pairs of these single-stage BEFs 81-86 couple interdigitally each other with phase shifts of Π/2 and thereby form altogether an interdigitally coupled dielectric BEF. Input to and output from this filter are effected through the resonant lines 81b and 86a.

[0046] Although the present invention has been described above with reference to only a limited number of examples, these examples are not intended to limit the scope of the invention. Many modifications and variations are possible within the scope of this invention.

[0047] For example, throughholes, whether for forming resonant lines therein or for containing a screening electrode, need not be circular in cross-section. If the through-holes are made in the shape of a horizontally elongated rectangle of flattened ellipse, the filter as a whole can be made thinner. Fig. 24, for example, shows a variation of the filter according to the tenth embodiment of this invention shown above in Fig. 22, having all its throughholes formed in an elliptical shape. Since the filters shown in Figs. 22 and 24 are different only in the cross-sectional shapes of their throughholes and are identical in all other aspects, same numerals are used to indicate corresponding components. In all examples, furthermore, it is to be understood that input and output connections can be formed in any known manners.

[0048] In summary, sufficient attenuation can be obtained both on the lower and higher frequency sides of the trap frequency by a dielectric BEF according to this invention. If such a filter is used in a mobile communication apparatus such as a portable telephone, it is possible to simplify the circuit structure by eliminating the isolator and the BPF which used to be necessary. Since the number of component parts becomes reduced, the production cost is also reduced. If the number of components to be soldered is reduced, reliability is improved, individual variations in characteristics are reduced among the products, and the yield is increased.

Claims

1. A dielectric band elimination filter comprising:

a dielectric block (101) having outer surfaces including two mutually opposite first and second end surfaces;

an outer conductor covering portions of said outer surfaces; and

two mutually coupled resonant lines (102, 103) formed extending in said dielectric block (101) between said end surfaces, each of said resonant lines (102, 103) having an open end which is not in contact with said outer conductor and a shorted end which is in contact with said outer conductor, said open and shorted ends of said two resonant lines are oppositely oriented; characterised in that said open end of one of said two resonant lines is unconnected to an outer circuit and said open end of said other of said resonant lines is connected to an outside circuit.

2. The dielectric filter of claim 1 wherein one of said end surfaces has a conductor-free area (102c, 103c) and said open end of one of said resonant lines is at said conductor-free area.

3. The dielectric filter of claim 1 wherein said open ends of said resonant lines (102, 103) are connected to end surface electrodes (102b, 103b) which are formed on said end surfaces and are insulated from said outer conductor.

4. The dielectric filter of claim I wherein said dielectric block (101) has throughholes (102a, 103b) formed therethrough between said end surfaces and said open ends are at conductor-free areas on inner surfaces of said throughholes (102a, 103a).

5. A dielectric band elimination filter as claimed in claim 1, wherein said dielectric block (10;20) has a plurality of single-stage band elimination filters (21-25) each having two interdigitally coupled resonant lines (1-4; 21a-25a, 21b-25b) extending between said first and second end surfaces inside throughholes (1a-4a) through said block, each mutually adjacent pair of said single-stage band elimination filters being interdigitally coupled or combline-coupled to each other with phase shift of π/2.

6. The dielectric filter of claim 5 further comprising an outer conductor which covers portions of outer surfaces of said dielectric block (10; 20), each of said two interdigitally coupled resonant lines (1-4; 21a-25a, 21b-25b) having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, said open and shorted ends of said two resonant lines of each of said single-stage band elimination filters (21-25) being oppositely oriented, the open end of one of said two resonant lines of each of said single-stage band elimination filters being formed at one of said end surfaces, the open end of the other of said two resonant lines of each of said single-stage band elimination filters being at an annular conductor-free area formed on inner surface of corresponding one of said throughholes (1a-4a).

7. The dielectric filter of claim 5 or claim 6 wherein said throughholes (1a-4a) are horizontally extending and horizontally arranged and have a horizontally elongated cross-sectional shape.

8. The dielectric filter of claim 5 further comprising an outer conductive covering portions of outer surfaces of said dielectric block (20), said resonant lines (21a-25a, 21b-25b) being arranged in two horizontal rows consisting of upper and lower rows and at least two vertical columns, each of said resonant lines having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, the open and shorted ends of the resonant lines on said upper row being formed respectively at said first and second end surfaces, the open and shorted ends of the resonant lines on said lower row being formed respectively at said second and first end surface, the pair of the resonant lines in each column being interdigitally coupled to each other to form a single-stage band elimination filter (21-25), each mutually adjacent pair of said single-stage band elimination filters being combline-coupled to each other with phase shift of π/2 therebetween.

9. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (30), each of said resonant lines (31a-35a, 31b-35b) having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, said resonant lines being arranged in two horizontal rows consisting of upper and lower rows and at least two vertical columns, the open ends of each pair of resonant lines which are horizontally or vertically next to each other being at different ones of said end surfaces, the pair of the resonant lines in each column being interdigitally coupled to each other to form a single-stage band elimination filter (31-35), each mutually adjacent pair of said single-stage band elimination filters being interdigitally coupled to each other with phase shift of π/2 therebetween.

10. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (20), said resonant lines (21a-25a, 21b-25b) being arranged in two horizontal rows consisting of upper and lower rows and at least two vertical columns, each of said resonant lines having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, the open and shorted ends of the resonant lines on said upper row being formed respectively at said first and second end surfaces, the open and shorted ends of the resonant lines on said lower row being formed respectively at said second and first end surface, the pair of the resonant lines in each column being interdigitally coupled to each other to form a single-stage band elimination filter (21-25), a screening electrode (41) connected to said outer conductor being provided between each of mutually adjacent pairs of said resonant lines on said upper row, each mutually adjacent pair of said single-stage band elimination filters being interdigitally coupled to each other with phase shift of π/2 therebetween.

11. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (50), each of said resonant lines (51a-53a, 51b-53b) having an open end which is connected to an open end electrode (51c-53c) insulated from said outer conductor and a shorted end which is connected to said outer conductor, said resonant lines being arranged in two horizontal rows consisting of upper and lower rows and at least two vertical columns, the open ends of each pair of resonant lines which are horizontally or vertically next to each other being at different ones of said end surfaces, the pair of the resonant lines in each column being interdigitally coupled toeach other to form a single-stage band elimination filter (51-53), a screening electrode (54) connected to said outer conductor being provided between each of mutually adjacent pairs of said resonant lines on said upper row.

12. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (60), said dielectric block also having a horizontally extending bottom part and an upwardly protruding central part, each of said resonant lines (61a-63a, 61b-63b) having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, said resonant lines forming at least three pairs, two of said resonant lines of each of said pairs being interdigitally coupled to each other to form a single-stage band elimination filter (61-63), the open and shorted ends of the resonant lines of each of said pairs being at different ones of said end surfaces, one of said pairs being vertically arranged, having one of said resonant lines in said upwardly protruding central part and the other of said resonant lines therebelow, two others of said pairs being horizontally arranged and formed on both sides of said vertically arranged pair in said horizontally extending part of said dielectric block.

13. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (70), said resonant lines (71a-73a, 71b-73b) being arranged in two horizontal rows consisting of upper and lower rows and at least three vertical columns including end columns and inner columns therebetween, each of said resonant lines having an open end and a shorted end, the pair of the resonant lines in each column being interdigitally coupled to each other to form a single-stage band elimination filter (71-73), the open and shorted ends of the interdigitally coupled pair of each of said single-stage band elimination filter being formed at opposite ones of said end surfaces, the open ends of the resonant lines in said end columns on said lower row being each connected to an open end terminal formed on one of said end surfaces of said dielectric block, the open ends of the resonant lines in said end columns on said upper row and in said inner columns being each formed at an annular conductor-free area (71d-73d) formed on inner surface of corresponding one of said throughhole.

14. The dielectric filter of claim 13 wherein said rows extend horizontally, and said throughholes have a horizontally elongated cross-sectional shape.

15. The dielectric filter of claim 5 further comprising an outer conductor covering portions of outer surfaces of said dielectric block (80), each of said resonant lines (81a-86a, 81b-86b) having an open end which is insulated from said outer conductor and a shorted end which is connected to said outer conductor, said resonant lines being arranged in at least three horizontal rows and at least four vertical columns, the open ends of each pair of resonant lines which are horizontally or vertically next to each other being at different ones of said end surfaces, screening electrodes (84) being provided between selected pairs of said resonant lines which are next to each other, pairs of the resonant lines horizontally next to each other being interdigitally coupled to form single-stage band elimination filters (81-86).

16. The dielectric filter of any of claims 8, 9, 10, 11, 12 and 15 wherein said throughholes having a horizontally elongated cross-sectional shape.

Ansprüche

1. Ein dielektrisches Bandsperrfilter mit folgenden Merkmalen:

einem dielektrischen Block (101), der äußere Oberflächen aufweist, die eine erste und eine zweite Endoberfläche aufweisen, die sich gegenüberliegen;

einem äußeren Leiter, der Abschnitte der äußeren Oberflächen bedeckt; und

zwei gegenseitig gekoppelten Resonanzleitungen (102, 103), die sich zwischen den Endoberflächen in dem dielektrischen Block (101) erstreckend gebildet sind, wobei jede der Resonanzleitungen (102, 103) ein Leerlaufende, das sich nicht in einem Kontakt mit dem äußeren Leiter befindet, und ein Kurzschlußende aufweist, das sich in einem Kontakt mit dem äußeren Leiter befindet, wobei die Leerlaufenden und die Kurzschlußenden der zwei Resonanzleitungen entgegengesetzt ausgerichtet sind; dadurch gekennzeichnet, daß das Leerlaufende einer der zwei Resonanzleitungen nicht mit einer äußeren Schaltung verbunden ist, und daß das Leerlaufende der anderen der Resonanzleitungen mit einer äußeren Schaltung verbunden ist.

2. Das dielektrische Filter gemäß Anspruch 1, bei dem eine der Endoberflächen einen leiterfreien Bereich (102c, 103c) aufweist, und sich das Leerlaufende von einer der Resonanzleitungen in dem leiterfreien Bereich befindet.

3. Das dielektrische Filter gemäß Anspruch 1, bei dem die Leerlaufenden der Resonanzleitungen (102, 103) mit Endoberflächenelektroden (102b, 103b) verbunden sind, die an den Endoberflächen gebildet sind, und die von dem äußeren Leiter isoliert sind.

4. Das dielektrische Filter gemäß Anspruch 1, bei dem der dielektrische Block (101) Durchgangslöcher (102a, 103b) aufweist, die durch denselben zwischen den Endoberflächen gebildet sind, und bei dem sich die Leerlaufenden in leiterfreien Bereichen an inneren Oberflächen der Durchgangslöcher (102a, 103a) befinden.

5. Das dielektrische Filter gemäß Anspruch 1, bei dem der dielektrische Block (10; 20) eine Mehrzahl von Einstufen-Bandsperrfiltern (21 - 25) aufweist, die jeweils zwei interdigital gekoppelte Resonanzleitungen (1 - 4; 21a - 25a, 21b - 25b) aufweisen, die sich zwischen der ersten und der zweiten Endoberfläche innerhalb der Durchgangslöcher (1a - 4a) durch den Block erstrecken, wobei jedes benachbarte Paar der Einstufen-Bandsperrfilter mit einer Phasenverschiebung von π/2 miteinander interdigital gekoppelt oder kammleitungsgekoppelt ist.

6. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (10; 20) bedeckt, wobei jede der zwei interdigital gekoppelten Resonanzleitungen (1 - 4; 21a - 25a, 21b - 25b) ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Leerlaufenden und die Kurzschlußenden der zwei Resonanzleitungen von jedem der Einstufen-Bandsperrfilter (21 - 25) entgegengesetzt ausgerichtet sind, wobei das Leerlaufende von einer der zwei Resonanzleitungen von jedem der Einstufen-Bandsperrfilter an einer der Endoberflächen gebildet ist, wobei sich das Leerlaufende der anderen der zwei Resonanzleitungen von jedem der Einstufen-Bandsperrfilter in einem ringförmigen leiterfreien Bereich befindet, der an der inneren Oberfläche eines entsprechenden der Durchgangslöcher (1a - 4a) gebildet ist.

7. Das dielektrische Filter gemäß Anspruch 5 oder Anspruch 6, bei dem sich die Durchgangslöcher (1a - 4a) horizontal erstrecken, horizontal angeordnet sind und eine horizontal längliche Querschnittsform aufweisen.

8. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (20) bedeckt, wobei die Resonanzleitungen (21a - 25a, 21b-25b) in zwei horizontalen Reihen angeordnet sind, die aus einer oberen und einer unteren Reihe und mindestens zwei vertikalen Spalten bestehen, wobei jede der Resonanzleitungen ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Leerlaufenden und die Kurzschlußenden der Resonanzleitungen in der oberen Reihe an der ersten bzw. der zweiten Endoberfläche gebildet sind, wobei die Leerlaufenden und die Kurzschlußenden der Resonanzleitungen in der unteren Reihe an der zweiten bzw. der ersten Endoberfläche gebildet sind, wobei das Paar der Resonanzleitungen in jeder Spalte miteinander interdigital gekoppelt ist, um ein Einstufen-Bandsperrfilter (21 - 25) zu bilden, wobei jedes gegenseitig benachbarte Paar der Einstufen-Bandsperrfilter mit einer Phasenverschiebung von π/2 zwischen denselben miteinander kammleitungsgekoppelt ist.

9. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (30) bedeckt, wobei jede der Resonanzleitungen (31a - 35a, 31b - 35b) ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Resonanzleitungen in zwei horizontalen Reihen angeordnet sind, die aus einer oberen und einer unteren Reihe und mindestens zwei vertikalen Spalten bestehen, wobei die Leerlaufenden von jedem Paar von Resonanzleitungen, die horizontal oder vertikal nahe zueinander liegen, sich auf unterschiedlichen der Endoberflächen befinden, wobei das Paar der Resonanzleitungen in jeder Spalte miteinander interdigital gekoppelt ist, um ein Einstufen-Bandsperrfilter (31 - 35) zu bilden, wobei jedes gegenseitig benachbarte Paar von Einstufen-Band-sperrfiltern mit einer Phasenverschiebung von π/2 zwischen denselben miteinander interdigital gekoppelt ist.

10. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (20) bedeckt, wobei die Resonanzleitungen (21a - 25a, 21b-25b) in zwei horizontalen Reihen angeordnet sind, die aus einer oberen und einer unteren Reihe und mindestens zwei vertikalen Spalten bestehen, wobei jede der Resonanzleitungen ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Leerlaufenden und die Kurzschlußenden der Resonanzleitungen in der oberen Reihe an der ersten bzw. der zweiten Endoberfläche gebildet sind, wobei die Leerlaufenden und die Kurzschlußenden der Resonanzleitungen in der unteren Reihe an der zweiten bzw. der ersten Endoberfläche gebildet sind, wobei das Paar von Resonanzleitungen in jeder Spalte miteinander interdigital gekoppelt ist, um ein Einstufen-Bandsperrfilter (21 - 25) zu bilden, wobei eine Abschirmelektrode (41), die mit dem äußeren Leiter verbunden ist, zwischen jedem von gegenseitig benachbarten Paaren der Resonanzleitungen in der oberen Reihe vorgesehen ist, wobei jedes gegenseitig benachbarte Paar der Einstufen-Bandsperrfilter mit einer Phasenverschiebung von π/2 zwischen denselben miteinander interdigital gekoppelt ist.

11. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (50) bedeckt, wobei jede der Resonanzleitungen (51a - 53a, 51b - 53b) ein Leerlaufende, das mit einer Leerlaufelektrode (51c - 53c) verbunden ist, die von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Resonanzleitungen in zwei horizontalen Reihen angeordnet sind, die aus einer oberen und einer unteren Reihe und mindestens zwei vertikalen Spalten bestehen, wobei sich die Leerlaufenden von jedem Paar von Resonanzleitungen, die sich horizontal oder vertikal nahe zueinander befinden, auf unterschiedlichen Endoberflächen befinden, wobei das Paar der Resonanzleitungen in jeder Spalte miteinander interdigital gekoppelt ist, um ein Einstufen-Bandsperrfilter (51-53) zu bilden, wobei eine Abschirmelektrode (54), die mit dem äußeren Leiter verbunden ist, zwischen jedem von gegenseitig benachbarten Paaren der Resonanzleitungen in der oberen Reihe vorgesehen ist.

12. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte der äußeren Oberflächen des dielektrischen Blocks (60) bedeckt, wobei der dielektrische Block ferner einen sich horizontal erstreckenden unteren Teil und einen nach oben vorstehenden Mittelteil aufweist, wobei jede der Resonanzleitungen (61a - 63a, 61b - 63b) ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Resonanzleitungen mindestens drei Paare bilden, wobei zwei der Resonanzleitungen von jedem der Paare miteinander interdigital gekoppelt sind, um ein Einstufen-Bandsperrfilter (61-63) zu bilden, wobei sich die Leerlaufenden und die Kurzschlußenden der Resonanzleitungen von jedem der Paare auf unterschiedlichen der Endoberflächen befinden, wobei eines der Paare vertikal angeordnet ist, wobei sich eine der Resonanzleitungen in dem nach oben vorstehenden Mittelteil befindet, und sich die andere der Resonanzleitungen darunter befindet, wobei zwei andere der Paare horizontal angeordnet sind und auf beiden Seiten des vertikal angeordneten Paars in dem sich horizontal erstreckenden Teil des dielektrischen Blocks gebildet sind.

13. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (70) bedeckt, wobei die Resonanzleitungen (71a - 73a, 71b - 73b) in zwei horizontalen Reihen angeordnet sind, die aus einer oberen und einer unteren Reihe und mindestens drei vertikalen Spalten bestehen, die Endspalten und innere Spalten dazwischen aufweisen, wobei jede der Resonanzleitungen ein Leerlaufende und ein Kurzschlußende aufweist, wobei das Paar der Resonanzleitungen in jeder Spalte miteinander interdigital gekoppelt ist, um ein Einstufen-Bandsperrfilter (71-73) zu bilden, wobei die Leerlaufenden und die Kurzschlußenden des interdigital gekoppelten Paars von jedem der Einstufen-Bandsperrfilter an gegenüberliegenden der Endoberflächen gebildet sind, wobei die Leerlaufenden der Resonanzleitungen in den Endspalten in der unteren Reihe jeweils mit einem Leerlaufanschluß verbunden sind, der auf einer der Endoberflächen des dielektrischen Blocks gebildet ist, wobei die Leerlaufenden der Resonanzleitungen in den Endspalten in der oberen Reihe und in den inneren Spalten jeweils in einem ringförmigen leiterfreien Bereich (71d - 73d) gebildet sind, der an einer inneren Oberfläche eines entsprechenden der Durchgangslöcher gebildet ist.

14. Das dielektrische Filter gemäß Anspruch 13, bei dem sich die Reihen horizontal erstrecken und die Durchgangslöcher eine horizontal längliche Querschnittsform aufweisen.

15. Das dielektrische Filter gemäß Anspruch 5, das ferner einen äußeren Leiter aufweist, der Abschnitte von äußeren Oberflächen des dielektrischen Blocks (80) bedeckt, wobei jede der Resonanzleitungen (81a - 86a, 81b - 86b) ein Leerlaufende, das von dem äußeren Leiter isoliert ist, und ein Kurzschlußende aufweist, das mit dem äußeren Leiter verbunden ist, wobei die Resonanzleitungen in mindestens drei horizontalen Reihen und mindestens vier vertikalen Spalten angeordnet sind, wobei sich die Leerlaufenden von jedem Paar von Resonanzleitungen, die sich horizontal oder vertikal nahe zueinander befinden, auf unterschiedlichen der Endoberflächen befinden, wobei Abschirmelektroden (84) zwischen ausgewählten Paaren der Resonanzleitungen vorgesehen sind, die sich nahe zueinander befinden, wobei Paare der Resonanzleitungen, die sich horizontal nahe zueinander befinden, miteinander interdigital gekoppelt sind, um Einstufen-Bandsperrfilter (81 - 86) zu bilden.

16. Das dielektrische Filter gemäß einem der Ansprüche 8, 9, 10, 11, 12 und 15, bei dem die Durchgangslöcher eine horizontal längliche Querschnittsform aufweisen.

Revendications

1. Filtre diélectrique de réjection de bande comprenant :

un bloc (101) de diélectrique comportant des surfaces extérieures incluant deux surfaces mutuellement opposées de première et seconde extrémités ;

un conducteur externe recouvrant des parties desdites surfaces externes ; et

deux lignes accordées (102, 103) mutuellement couplées, formées de façon à s'étendre dans ledit bloc (101) de diélectrique entre lesdites surfaces d'extrémité, chacune desdites lignes accordées (102, 103) ayant une extrémité ouverte qui n'est pas en contact avec ledit conducteur externe et une extrémité en court-circuit qui est en contact avec ledit conducteur externe, lesdites extrémités ouverte et en court-circuit desdites deux lignes accordées étant orientées de façon opposée ;

   caractérisé en ce que ladite extrémité ouverte de l'une desdites deux lignes accordées n'est pas connectée à un circuit externe et en ce que ladite extrémité ouverte de ladite autre desdites lignes accordées est connectée à un circuit extérieur.

2. Filtre diélectrique selon la revendication 1, dans lequel l'une desdites surfaces d'extrémité comporte une zone (102c, 103c) exempte de conducteur et ladite extrémité ouverte de l'une desdites lignes accordées est au niveau de ladite zone exempte de conducteur.

3. Filtre diélectrique selon la revendication 1, dans lequel lesdites extrémités ouvertes desdites lignes accordées (102, 103) sont connectées à des électrodes de surface d'extrémité (102b, 103b) qui sont formées sur lesdites surfaces d'extrémité et qui sont isolées dudit conducteur externe.

4. Filtre diélectrique selon la revendication 1, dans lequel ledit bloc (101) de diélectrique comporte des trous traversants (102a, 103b) qui y sont formés entre lesdites surfaces d'extrémité, et dans lequel lesdites extrémités ouvertes sont au niveau de zones exemptes de conducteur sur les surfaces internes desdits trous traversants (102a, 103b).

5. Filtre diélectrique de réjection de bande selon la revendication 1, dans lequel ledit bloc (10 ; 20) de diélectrique comporte une pluralité de filtres (21 à 25) de réjection de bande à un seul étage comportant chacun deux lignes accordées (1 à 4 ; 21a à 25a, 21b à 25b) couplées de manière interdigitée, s'étendant entre lesdites première et seconde surfaces d'extrémité à l'intérieur de trous traversants (1a à 4a) qui traversent ledit bloc, chaque paire mutuellement adjacente desdits filtres de réjection de bande à un seul étage étant couplée de manière interdigitée, ou couplée en peigne, l'une à l'autre avec un déphasage de π/2.

6. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe qui recouvre des parties de surfaces externes dudit bloc (10 ; 20) de diélectrique, chacune desdites deux lignes accordées (1 à 4 ; 21a à 25a ; 21b à 25b) couplées de manière interdigitée comportant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, lesdites extrémités ouvertes et en court-circuit desdites deux lignes accordées de chacun desdits filtres (21 à 25) de réjection de bande à un seul étage étant orientées de façon opposée, l'extrémité ouverte de l'une desdites deux lignes accordées de chacun desdits filtres de réjection de bande à un seul étage étant formée au niveau de l'une desdites surfaces d'extrémité, l'extrémité ouverte de l'autre desdites deux lignes accordées de chacun desdits filtres de réjection de bande à un étage étant au niveau d'une zone annulaire exempte de conducteur formée sur la surface interne de l'un, correspondant, desdits trous traversants (1a à 4a).

7. Filtre diélectrique selon la revendication 5 ou la revendication 6, dans lequel lesdits trous traversants (1a à 4a) s'étendent horizontalement et sont agencés horizontalement et ont une forme de section transversale allongée horizontalement.

8. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (20) de diélectrique, lesdites lignes accordées (21a à 25a, 21b à 25b) étant agencées en deux rangées horizontales constituées de rangées supérieure et inférieure et en au moins deux colonnes verticales, chacune desdites lignes accordées comportant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, les extrémités ouverte et en court-circuit des lignes accordées sur ladite rangée supérieure étant formées, respectivement, au niveau desdites première et seconde surfaces d'extrémité, les extrémités ouverte et en court-circuit des lignes accordées sur ladite rangée inférieure étant formées, respectivement, au niveau desdites seconde et première surfaces d'extrémité, la paire de lignes accordées dans chaque colonne étant couplée de manière interdigitée l'une à l'autre pour former un filtre (21 à 25) de réjection de bande à un seul étage, chaque paire mutuellement adjacente desdits filtres de réjection de bande à un seul étage étant couplée en peigne l'une à l'autre avec un déphasage de π/2 entre les deux.

9. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (30) de diélectrique, chacune desdites lignes accordées (31a à 35a, 31b à 35b) comportant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, lesdites lignes accordées étant agencées en deux rangées horizontales constituées de rangées supérieure et inférieure et en au moins deux colonnes verticales, les extrémités ouvertes de chaque paire de lignes accordées voisines les unes des autres horizontalement ou verticalement étant au niveau de certaines, différentes, desdites surfaces d'extrémité, la paire de lignes accordées dans chaque colonne étant couplée de manière interdigitée l'une à l'autre pour former un filtre (31 à 35) de réjection de bande à un seul étage, chaque paire mutuellement adjacente de filtre de réjection de bande à un seul étage étant couplée de manière interdigitée l'une à l'autre avec un déphasage de π/2 entre les deux.

10. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (20) de diélectrique, lesdites lignes accordées (21a à 25a, 21b à 25b) étant agencées en deux rangées horizontales constituées de rangées supérieure et inférieure et en au moins deux colonnes verticales, chacune desdites lignes accordées comportant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, les extrémités ouverte et en court-circuit des lignes accordées sur ladite rangée supérieure étant formées, respectivement, au niveau desdites première et seconde surfaces d'extrémité, les extrémités ouverte et en court-circuit des lignes accordées sur ladite rangée inférieure étant formées, respectivement, au niveau desdites seconde et première surfaces d'extrémité, la paire de lignes accordées dans chaque colonne étant couplée de manière interdigitée l'une à l'autre pour former un filtre (21 à 25) de réjection de bande à un seul étage, une électrode (41) de blindage connectée audit conducteur externe étant disposée entre chacune de paires mutuellement adjacentes desdites lignes accordées sur ladite rangée supérieure, chaque paire mutuellement adjacente desdits filtres de réjection de bande à un seul étage étant couplée de manière interdigitée l'une à l'autre avec un déphasage de π/2 entre les deux .

11. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (50) de diélectrique, chacune desdites lignes accordées (51a à 53a, 51b à 53b) comportant une extrémité ouverte qui est connectée à une électrode à extrémité ouverte (51c à 53c) isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, lesdites lignes accordées étant agencées en deux rangées horizontales constituées de rangées supérieure et inférieure et en au moins deux colonnes verticales, les extrémités ouvertes de chaque paire de lignes accordées voisines les unes des autres horizontalement ou verticalement étant au niveau de certaines, différentes, desdites surfaces d'extrémité, la paire de lignes accordées dans chaque colonne étant couplée de manière interdigitée l'une à l'autre pour former un filtre (51 à 53) de réjection de bande à un seul étage, une électrode (54) de blindage connectée audit conducteur externe étant disposée entre chacune de paires mutuellement adjacentes desdites lignes accordées sur ladite rangée supérieure.

12. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (60) de diélectrique, ledit bloc de diélectrique comportant aussi une partie de base s'étendant horizontalement et une partie centrale en saillie vers le haut, chacune desdites lignes accordées (61a à 63a, 61b à 63b) ayant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, lesdites lignes accordées formant au moins trois paires, deux desdites lignes accordées de chacune desdites paires étant couplées de manière interdigitée l'une à l'autre pour former un filtre (61 à 63) de réjection de bande à un seul étage, les extrémités ouverte et en court-circuit des lignes accordées de chacune desdites paires étant au niveau de certaines, différentes, desdites surfaces d'extrémité, l'une desdites paires étant agencée verticalement, comportant l'une desdites lignes accordées dans ladite partie centrale formant saillie vers le haut et l'autre desdites lignes accordées étant au-dessous de celle-ci, deux autres desdites paires étant agencées horizontalement formées sur les deux côtés de ladite paire agencée verticalement dans ladite partie s'étendant horizontalement dudit bloc de diélectrique.

13. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (70) de diélectrique, lesdites lignes accordées (71a à 73a, 71b à 73b) étant agencées en deux rangées horizontales constituées de rangées supérieure et inférieure et en au moins trois colonnes verticales incluant des colonnes d'extrémité et, entre elles, des colonnes internes, chacune desdites lignes accordées comportant une extrémité ouverte et une extrémité en court-circuit, la paire de lignes accordées dans chaque colonne étant couplée de manière interdigitée l'une à l'autre pour former un filtre (71 à 73) de réjection de bande à un seul étage, les extrémités ouverte et en court-circuit de la paire couplée de manière interdigitée de chacun desdits filtres de réjection de bande à un seul étage étant formées au niveau de celles qui sont opposées desdites surfaces d'extrémité, les extrémités ouvertes desdites lignes accordées dans lesdites colonnes d'extrémité sur ladite rangée inférieure étant chacune connectée à une borne d'extrémité ouverte formée sur l'une desdites surfaces d'extrémité dudit bloc de diélectrique, les extrémités ouvertes des lignes accordées dans lesdites colonnes d'extrémité sur ladite rangée supérieure et dans lesdites colonnes internes étant chacune formées au niveau d'une zone annulaire (71d à 73d) exempte de conducteur, formée sur la surface interne de l'un, correspondant, desdits trous traversants.

14. Filtre diélectrique selon la revendication 13, dans lequel lesdites rangées s'étendent horizontalement, et lesdits trous traversants ont une forme de section transversale allongée horizontalement.

15. Filtre diélectrique selon la revendication 5, comprenant en outre un conducteur externe recouvrant des parties de surfaces externes dudit bloc (80) de diélectrique, chacune desdites lignes accordées (81a à 86a, 81b à 86b) comportant une extrémité ouverte qui est isolée dudit conducteur externe et une extrémité en court-circuit qui est connectée audit conducteur externe, lesdites lignes accordées étant agencées en au moins trois rangées horizontales et en au moins quatre colonnes verticales, les extrémités ouvertes de chaque paire de lignes accordées voisines les unes des autres horizontalement ou verticalement étant au niveau de certaines, différentes, desdites surfaces d'extrémité, des électrodes (84) de blindage étant disposées entre des paires choisies desdites lignes accordées qui sont voisines l'une de l'autre, des paires de lignes accordées voisines l'une de l'autre horizontalement étant couplées de manière interdigitée pour former des filtres (81 à 86) de réjection de bande à un seul étage.

16. Filtre diélectrique selon l'une quelconque des revendications 8, 9, 10, 11, 12 et 15, dans lequel lesdits trous traversants ont une forme de section transversale allongée horizontalement.

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