[0001] The invention refers to a connector for a high frequency transmission path.
PRIOR ART
[0002] From the European patent application EP O 362 841 it has become known to connect
a multiplicity of coaxial cables with a printed circuit board (PCB). The PCB has an
array of contact pins onto which coaxial receptacles of coaxial cables are plugged.
Usually, a coaxial cable has a predetermined impedance. The PCB usually is matched
to this impedance, too. This is also valid for a connection of a contact pin with
a receptacle.
[0003] From the US patent No. 4,995,815, the French patent No. 2,552,939 and the British
patent No. 2,252, 578 is has become known to connect coaxial cables with a PCB extending
parallel to the PCB through a connector element. For this purpose, the signal wire
in the connector element is encircled more or less by a shielding which in turn is
connected with the shielding of the coaxial cable and the mass conductor of the PCB.
Due to the geometrical configuration of coaxial cable and PCB it is mandatory to bend
the signal conductor in the connector element about 90
0. The screening of the signal wire portion inserted into the PCB is achieved by a plurality
of pins located around the signal wire which are also inserted into the PCB. By means
of such a connector element, an approximate impedance matching is accomplished for
the connector elements. However, the manufacture of such connector elements is relatively
expensive.
[0004] From the prospectus "Control Impedance of 50 Ohms in only 1/28 the Space" of "Chabin
Transmission Line Applications 3 Electronic Products Division" dated January 1, 1988
it has become known to provide connectors for a coaxial cable wherein the signal and
the mass conductors are not coaxially arranged, rather, are located in parallel and
are enclosed by an electrically conductive housing. If such connectors are connected
to a PCB, a mismatching may occur, particularly if for example contact pins on the
PCB are not completely received by the female connector part, rather, a space is left
between connector and PCB. Above all, this space cannot be avoided if coaxial cable
or connector, respectively, and PCB include an angle unequal to 90°. Impedance mismatching
in the conventional high frequency technology is not serious as far as predetermined
limits are not exceeded. They lead, however, to undesired reflections if the transmission
frequency attains high valves, e.g. above 500 MHz up to 1 GHz. The distortions occurring
cannot be neglected.
[0005] From the US patent No. 4,789,357 it has become known to locate a conductive housing
around the pins of a pin header as a continuation of the shielding of a coaxial cable
or a shielded receptacle connected with the coaxial cable, respectively. From the
European patent application No. 0,131,248, a header has become known wherein a conductive
sheet extends partially around the contact pins, with the sheet connected to the conductive
housing of a connector. The known header of the European patent application 0,747,205
has a channel-shaped part of conductive sheet associated with the signal contact pins,
with the walls of the sheet contacting the conductive housing of the mating connector.
From the German patent specification No. 39 04 461, a multi-terminal high frequency
plug-type connection is known, wherein a connector of electrically conductive material
and the signal conductors are separated by an insulating dielectric material.
[0006] With the embodiments described, a sufficient impedance matching may be achieved.
However, the construction measures to achieve such matching lead to an expensive manufacture
of the connector elements.
SUMMARY OF THE INVENTION
[0007] The invention provides a connector element for a high frequency transmission path
which is adapted to interconnect components of the transmission path with a predetermined
impedance.
[0008] This invention demonstrates that an expensive shielding in the area of the connector
element is not necessary if a tuning of the impedance takes place in a specific manner.
Non-shielded conductor portions of conventional connector elements normally have an
impedance which is too high, i.e. higher than the usual impedance values of 50, 75,
or 90 Ohm. The impedance of a high frequency transmission line depends upon the inductance
and the capacitance of the path as well. If the capacitance of such a transmission
path is increased, the impedance decreases and vice versa. The invention uses these
principles in that the conductor portions of the connector element are provided with
opposite surface portions being spaced from each other with an amount which deviates
from that of adjacent parts of the conductor portions. In this manner for example
the capacitance between the conductor portions can be increased significantly. By
means of the invention, the impedance of a conductor element for a high frequency
transmission path, thus, can be reduced or enlarged, with the space between the terminals
of the conductor portions remaining unchanged.
[0009] As known, the capacitance is dependent upon the distance and the effective surface
area of electrodes as well as upon dielectric constant of the medium between the electrodes.
According to an embodiment of the invention, the surface portions may be at least
partially enclosed by a dielectric material. By a selection of the mentioned parameter,
the desired impedance value may be achieved and thus, the desired matching or mismatching
with respect to the impedance of the transmission path.
[0010] Different geometrical configurations are conceivable to change the capacitance between
two conductor portions of the connector element. In the following description only
examples are outlined wherein the capacitance is increased and correspondingly, the
impedance is reduced. In an embodiment of the invention, the surface portions are
parallel to each other. They can be provided with a width larger than the width or
the diameter of adjacent parts of the conductor portions. The conductor portions for
example can be provided with a square or circular cross section. In the retaining
member, the conductor portions may have a larger width than outside the retaining
member. In order to accomplish such configuration, the conductor portions can be provided
with a thickening which may be integrally formed with the conductor portions. The
thickening can be for example circular or rectangular in cross section. A circular
expansion leads to a relatively small increase in the capacitance. It has the further
disadvantage similar to that of the rectangular thickening that the space between
adjacent pairs of conductor portions is also reduced resulting in an improved electro-magnet
coupling of adjacent signal conductors. This may cause undesired cross talk between
adjacent signal conductors. Therefore, a preferred embodiment of the invention provides
a thickening which is triangular in cross section, with the opposite sides of the
triangle being approximately parallel. The triangular shape has the advantage that
a significant increase in the capacitance between ground and signal conductor is achieved
while the capacitance between adjacent ground or signal conductors, respectively,
is substantially unvaried.
[0011] According to a further embodiment of the invention, the increased area may be an
extension T-shaped in cross section, with the transverse web of the extensions of
opposite conductor portions being approximately parallel. Also with the embodiment,
cross talk can be substantially avoided.
[0012] In a further embodiment of the invention, the surface portions are formed by a coining
of integral conductor portions. If conductor portions or pairs of conductors are coined
in the common plane by bending them towards each other so that the coined portions
extend parallel with a smaller space therebetween, the capacitance of this transmission
portion is also increased. Preferably, the coined portions are flattened in order
to enlarge the cooperating surfaces of the conductor portions. Furthermore, the coined
area may have a larger width than adjacent parts of the conductor portions. Such conductor
portions can be manufactured relatively simply. The blanks can be made by punching
or cutting from wire material while the coined portions are made by a coining step.
[0013] It is also possible to produce the surface portions by separate parts which are suitably
electrically attached to the conductor portions. The separate parts can be attached
to the conductor portions by welding, soldering, adhering or the like. Alternately,
the separate parts can be plugged onto the conductor portions. The separate parts
can be formed as clips or the like in order to attach them to the conductor portions
by a snapping connection. A further embodiment of the invention provides separate
parts having projection legs at the end, with a slot formed in the legs from the free
end thereof and adapted to accommodate the conductor portion in aligned slots. Preferably,
the separate parts are made of sheet material. However, they can be also manufactured
of solid material and they may be provided with a triangular, T-shaped, rectangular,
circular or the like cross sections similar to the above discussed expansions.
[0014] The parts of the conductor portions outside the retaining member are preferably straight
and parallel and for example may be pin-shaped to permit an insertion into correspondence
receptacles or openings of PCBs. The part of the conductor portions outside the retaining
member may include an angle, e.g. 90°. Inside the dielectric member, the part of the
conductor portions providing the surface portions may be curved in order to achieve
an increase of the capacitance throughout the total length within the retaining member.
[0015] As already mentioned, the parts of the conductor portions outside the retaining member
may be pin-shaped. Alternatively, these parts can be formed as receptacles, e.g. to
be connected with contact pins on a PCB.
[0016] The connector element according to the invention can be used for a number of applications.
It can be for example used to establish a connection between two PCBs. The PCBs may
be located parallel or include an angle relative to each other. The connector element
for example can be located adjacent an edge of the PCB and be connected with a bus
or the like. A further application for example is to interconnect a female connector
part and PCB, with the connector part and the PCB may have an arbitrary angle therebetween.
[0017] A third application is to interconnect two female connector parts including an arbitrary
angle therebetween. Finally, the connector element according to the invention may
interconnect a male connector part and a PCB.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention is subsequently explained with reference to accompanied drawings, wherein
Fig. 1 is a perspective view of the connection of a plug-type connector with a PCB
through a pin header with a connector elements according to the invention,
Fig. 2 is a perspective view of a further embodiment of a connector element according
to the invention,
Fig. 3 is a perspective view of a third embodiment of a connector element according
to the invention,
Fig. 4 is a perspective view of a fourth embodiment of a connector element according
to the invention,
Fig. 5 is a perspective view of a fifth embodiment of a connector element according
to the invention,
Fig. 6 is a perspective view of a sixth embodiment of a connector element according
to the invention,
Fig. 7 is a perspective view of a seventh embodiment of a connector element according
to the invention, and
Fig. 8 is a perspective view of an eighth embodiment of a connector element according
to the invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0019] In Fig. 1, three parallelepiped female plug- shaped connector elements 10 are illustrated
connected with coaxial cable 12. The housing 14 of conductive material is connected
with the shielding (not shown) of cable 12. Further, a connector element 16 is depicted
having a parallelepiped retainer member 18 of dielectric material and a plurality
of similar pin-shaped elements 20. Member 18 rests on a printed circuit board 22 (PCB)
which is diagrammatically illustrated. The pin-shaped elements or conductor portions
20 are arranged in pairs. The row of adjacent pins 24, for example, serve as signal
conductors and the opposite row of conductor portions 26 are, for example, ground
conductors. As can be seen, the conductor portions 24, 26 consist of three parts.
One part or section 28 or 30, respectively, is embedded in the material of member
18. Contact pins 32, 34 rectangular in cross section extend above and below member
18, respectively. The contact pins 34 are accommodated by holes (not shown) in PCB
22. A connector 10 may be plugged onto each pair of contact pins 24, 26 as indicated
in Fig. 1.
[0020] The intermediate portions 28, 30 of contact elements 24, 26 are identically shaped
so that only portion 30 is discussed in more detail. It is U-shaped and includes two
parallel spaced leg portions 38, 40 and a web portion 42 therebetween. The leg portions
38, 40 are triangularly shaped, with one peak attached to the contact pins 32, 34.
The web portion 42 has the same width as the edge of the leg portions 38, 40 at the
ends thereof. The U-shaped portions 28, 30 may be integrally formed with the elements
24, 26, e.g. through a suitable coining step. However, it is also conceivable to make
portions 28, 30 separately and to attach them to the contact pins 32, 34 by welding
or soldering.
[0021] As can be seen, the opposite surfaces of the web portions 42 of the intermediate
parts 28, 30 are close to each other and have a larger surface area than the contact
pins 32, 34 outside member 38 which serves as retaining body. The capacitance of the
pairs of conductor portions 24, 26 in the range of the intermediate parts 28, 30,
thus, is substantially higher than outside retaining member 18. On the other hand,
the capacitance between adjacent signal conductor portions 24 or between adjacent
ground conductor portions 26 is substantially constant if compared with intermediate
portions would be merely throughgoing extensions of the contact pins 32, 34. Thus,
the danger of cross talk is not higher than with conventional connector elements.
[0022] The Figures 2 to 5 depict modifications of the connector element 16 of Fig. 1. Therefore,
similar parts are provided with the same reference number added by a character.
[0023] A connector element 16 a of Fig. 2 has a parallelepiped retaining member 18a of dielectric
material. It includes a plurality of contact elements 20, i.e. pin-shaped signal contact
elements 24a and pin-shaped ground contact elements 26a which are arranged in pairs.
Each of the elements 24a, 26a includes contact pins 32a, 34a rectangular in cross
section on opposite ends retaining member 18a. Thickened portions 44 are rectangular
in cross section and are provided interiorly of the dielectric retaining member 18a.
The contact elements 24a, 26a, or the pairs of conductor portions, respectively, have
a significantly greater capacitance in the area of retaining member 18a. In contrast
to the embodiment of Fig. 1, also the capacitance between adjacent signal conductor
portions 24a or between adjacent ground conductor portions 26a is increased which
increases the risk or cross talk. The thickening 44 may be integrally formed with
conductor portions 24a, 26a, however, it can be separately formed and fitted onto
the pins 32a, 34a.
[0024] Fig. 3 shows a connector element 16b including a parallelepiped member 18b of dielectric
material. Pin-shaped contact elements or conductor portions 24b, 26b form pairs of
contact elements 20b, with the contact pins 32b, 34b outside retaining member 18b
having circular cross section. In the area of retaining member 18b, the conductor
portions 24b, 26b are provided with an expanded portion 46 triangular in cross section,
with the portion 46 arranged such that a surface 48 of a portion 46 is close and parallel
to the corresponding surface of the portion 46 of the opposite conductor portion.
Consequently, the axis of the pin portions 32b, 34b extend through the peaks of the
triangle. Similar to the embodiment of Fig. 2, the capacitance between signal conductor
portion 24b and ground conductor portion 26b is increased. The triangular shape reduces
the cross talk if compared with the embodiment of Fig. 2 because the capacitance between
adjacent signal conductor portions 24b or ground connector portions 26b, respectively,
is only marginally influenced by expanded portion 46.
[0025] In the embodiment of Fig. 4, pin-shaped conductor elements 24c, 26c have extensions
46c T-shaped in cross section, with the transverse web thereof having a surface 48c
and the surfaces 48c of opposite conductor portions 24c, 26c of the pairs of conductor
portions being parallel and relatively close to each other. The contact pins 32c,
34c are rectangular or square, respectively, in cross section. Extensions 46c again
increase the capacitance between signal conductor portions 24c and ground conductor
portion 26c significantly, while the capacitance between adjacent signal conductor
portions 24c or adjacent ground conductor portions 26c is only changed a small extent
relative to a configuration without such extensions 46c.
[0026] In the embodiments of Fig. 3 and 4, the extensions 46 and 46c, respectively, are
formed integrally with the conductor portions 24c, 26c. It is understood that separate
parts could be formed which are attached to the conductor portions in a suitable manner.
With the connector element 16d of Fig. 5, the conductor portions 24d, 26d are formed
by throughgoing pins of square cross section constituting upper contact pins 32d and
lower contact pins 34d. Parts 50, U-shaped in cross section, are attached to the conductor
portions 24d, 26d. They are made of conductive sheet material and have parallel legs
52, 54 and a web portion 56 interconnecting the legs. Slots 58 are cut in the legs
from the free end thereof which slots are adapted to accommodate the conductor portions
24d, 26d. The parts 50 can be clamped on the conductor portions 24d, 26d or attached
thereto by welding or soldering. The opposite surfaces 60 of the web portions 56 are
parallel and relatively close to each other. These surfaces increase the capacitance
between signal conductor portion 24d and ground conductor portion 26d of pairs of
contact elements.
[0027] In the embodiments of Figs. 1 to 5, the conductor portions are straight, i.e. the
contact pins on both sides of the retaining member 18 to 18d are aligned or located
on a common axis. In the embodiments of Figs. 6 and 7, the contact pins include and
angle of 90°. A member or body 64 approximately trapezoidal in cross section of suitable
dielectric material retains pairs of signal and ground conductor portions 66, 68,
respectively, with the ends thereof defining contact pins of square cross section
including an angle of 90° therebetween. Each pair of conductor portions 66, 68 are
located in a common plane. Inside the retaining body 64, the conductor portions 66,
68 are flattened and broadened as shown at 70 and 72, respectively. Further, the flattened
portions 70, 72 are closer to each other than the other parts of the conductor portions
66, 68 outside dielectric retaining body 64. The portions 70, 72 thus, define a range
of higher capacitance.
[0028] In the embodiment of Fig. 7, curved conductor portions 66a, 68a of square cross section
and curved approximately at an angle of 90 are retained by a dielectric retaining
body 64a similar to retaining body 64. The conductor portions 66a, 68a are also provided
with outer contact pins including an angle of approximately 90°. Bracket-shaped elements
50a include orthogonally extending legs 52a, 54a at the ends thereof having slots
76 formed from the free ends thereof for the accommodation of the curved part 78 of
conductor portions 66a, 68a. The legs 52a, 54a are interconnected through a flat curved
web portion 80. The curved web portion 80 follwos the course of the bent parts 68
of the conductor portions 66a, 68a. The parts 70 are also formed of sheet material.
The web portions 80 are located on opposite sides of conductor portions 66a, 68a so
that closely spaced parallel surfaces are formed in order to increase capacitance.
[0029] It should be mentioned that the connector elements 16 to 16d and 62, 62a are adapted
to be connected with different components of a high frequency transmission path, e.g.
with a PCB as shown in Fig. 1 or with connector elements including receptacles. It
is also understood that instead of the contact pins disclosed, receptacles could be
used without having the principles discussed above.
[0030] It is not necessary that the portions or surfaces altering the capacitance property
of conductor portions are enclosed by rigid dielectric material, rather, the dielectric
can be air. In Fig. 7, it is indicated by a dash-dotted line that the retaining body
62a may have smaller outer dimensions. The parts 50a including the legs 52a, 54a project
beyond body 62a whereby a portion of the dielectric medium is air.
[0031] The retaining body 64b of the embodiment of Fig. 8 differs from that of Fig. 6 in
that it includes square ports or openings 86 on one side which are aligned with receptacles
88 at the end of conductor portions 70b, 72b. The receptacles 88 are formed by two
spaced tongues 90, 92, with tongue 90 being a part of the flat conductor portion 70b,
72b, respectively, and tongue 92 may be a separate flat part or attached to tongue
90 through a web (not shown).
1. A connector element for a high frequency transmission path, comprising at least
a pair of spaced conductor portions defining a signal and a ground conductor, said
signal and ground conductors having parts retained by a dielectric retaining member,
said parts having opposite spaced surface portions, with the ends of said conductor
portions including means for the connection with an adjacent electrical component,
characterized in that order to change the capacitance along the length of the conductor
portions, opposite surface portions of said conductor portions have a configuration
and spacing changed from that of said conductor portions to afford a capacitance along
the opposite surfaces portions of said retained parts to match the impedance between
said conductor portions.
2. The connector element of claim 1, wherein said parts of said conductor portions
including said surface portions are at least partially enclosed by said dielectric
retaining member.
3. The connector element of claim 1 or 2, wherein said surface portions are parallel.
4. The connector element of claim 1, wherein said surface portions have a width larger
than the width of adjacent parts of said conductor portions.
5. The connector element of claim 1, wherein said conductor portions are integrally
formed and said surface portions of said parts are formed by an extension of said
integrally formed conductor portions.
6. The connector element of claim 5, wherein said extension is circular in cross section.
7. The connector element of claim 5, wherein said extension is rectangular in cross
section.
8. The connector element of claim 5, wherein said extension is triangular in cross
secton with said opposite surfaces being sides of said triangular extensions and being
disposed approximately parallel.
9. The connector element of claim 5, wherein said extension includes an extension
T-shaped in cross section, with the transverse webs of said extensions forming said
opposite surfaces and being approximately parallel.
10. The connector element of claim 1, wherein said surface portions are formed by
a coining of said integrally formed conductor portions.
11. The connector element of claim 1, wherein said surface portion has a greater width
than adjacent parts of said connector portions.
12. The connector element of claim 10, wherein said coined portion has a larger width
than adjacent parts of said connector portions.
13. The connector elements of claim 1, wherein said surface portions are formed by
separate parts attached to said connector portions.
14. The connector element of claim 13, wherein said separate parts are attached to
said conductor portions by welding, soldering, adhering or the like.
15. The connector element of claim 13, wherein said separate parts are adapted to
be plugged onto said conductor portions.
16. The connector element of claim 15, wherein said separate parts have cantilevered
legs at the ends thereof with slots being formed from the free end in said legs and
said aligned slots accommodating a said conductor portion.
17. The connector element of claim 14, wherein said separate parts are bent or flat
material.
18. The connector element of claim 14, wherein said separate parts consist of solid
material and are one of triangular, T-shaped, rectangular, circular or the like in
cross section.
19. The connector element of claim 1, wherein with a plurality of adjacent pairs of
said conductor portions said surface portions are formed such that the capacitance
between said adjacent signal conductor portions or said ground conductor portions,
respectively, is significantly changed and the capacitance between adjacent signal
conductor portions or said ground conductor portions is left substantially unchanged.