[Technical Field]
[0001] The present invention relates to an antenna-device substrate and an antenna device
which are capable of supporting multiple resonance frequencies.
[Background Art]
[0002] Conventionally, in order to multiple-resonate the resonance frequency of an antenna,
antennas provided with a radiation electrode and a dielectric block or an antenna
device using a switch and a controlled voltage source have been proposed for communication
devices.
[0003] For example, in Patent Literature 1, which is conventional technology using a dielectric
block, a composite antenna in which high efficiency is obtained by forming a radiation
electrode on a resin molded body and further integrating a dielectric block using
an adhesive is proposed.
[0004] In addition, in Patent Literature 2, which is conventional technology using a switch
and a controlled voltage source, an antenna device having a first radiation electrode,
a second radiation electrode, and a switch interposed between a middle portion of
the first radiation electrode and a base end portion of the second radiation electrode
and configured to electrically connect or disconnect the second radiation electrode
to or from the first radiation electrode is proposed.
[Citation List]
[Patent Literatures]
[0005]
[Patent Literature 1]
Japanese Unexamined Patent Application, First Publication No. 2010-81000
[Patent Literature 2]
Japanese Unexamined Patent Application, First Publication No. 2010-166287
[Summary of Invention]
[Technical Problem]
[0006] However, the following problems remain even in the above-described conventional technology.
[0007] That is, in the technology based on a dielectric block as disclosed in Patent Literature
1, a dielectric block for exciting the radiation electrode is used and designs of
a dielectric block, a radiation electrode pattern, etc. are necessary for each device
or antenna performance deteriorates according to design conditions or there is inconvenience
in that the number of unstable factors increases. In addition, because the radiation
electrode is formed on a surface of the resin molded body, it is necessary to design
a radiation electrode pattern on the resin molded body, an antenna design and a metal
mold design are necessary according to a communication device to be mounted or its
use, and a significant increase in cost is caused. Further, because the dielectric
block and the resin molded body are integrated using an adhesive, there is inconvenience
in that antenna performance is degraded or the number of unstable factors increases
according to an adhesive condition (a thickness of an adhesive, an adhesive area,
or the like) other than a Q value of the adhesive.
[0008] In addition, there is a problem in that the configuration of the controlled voltage
source, a reactance circuit, or the like is necessary in order to switch the resonance
frequency using the switch in the case of the antenna device using the switch and
the controlled voltage source as disclosed in Patent Literature 2, the antenna configuration
is complex according to each device, a degree of freedom of design is inadequate,
and antenna adjustment is difficult.
[0009] The present invention has been made in view of the aforementioned problems and an
objective of the invention is to provide an antenna-device substrate and an antenna
device that enable flexible adjustment of multiple resonance frequencies, can inexpensively
and simply secure antenna performance according to each use or device, and enable
reduction in size or thickness.
[Solution to Problem]
[0010] The present invention has adopted the following configuration for solving the above-described
problems. That is, according to a first present invention, an antenna-device substrate
includes an insulating substrate main body; and first to fourth elements patterned
using metal foils on the substrate main body and a ground plane, wherein the first
element extends to have a base end on which a power feeding point is provided in the
vicinity of the ground plane and have a first connector to which a first passive element
is contactable and an antenna element of a dielectric antenna in this order, wherein
the second element extends to have a base end connected between the power feeding
point of the first element and the first connector and have a second connector to
which a second passive element is connectable in the middle, wherein the third element
extends to have a base end to which the power feeding point is connected and have
a third connector to which a third passive element is connectable in the middle, wherein
the fourth element extends to have a base end connected between the power feeding
point of the third element and the third connector and have a fourth connector to
which a fourth passive element is connectable in the middle, and wherein the first
to fourth elements extend with gaps from adjacent elements and the ground plane so
that stray capacitance between the adjacent elements and stray capacitance with the
ground plane are able to occur.
[0011] Because the first to fourth elements extend with the gaps from the adjacent elements
and the ground plane so that stray capacitance between the adjacent elements and the
stray capacitance with the ground plane can occur in the antenna-device substrate,
the substrate can be provided with a multiple resonance (double to quadruple resonance)
by effectively employing the stray capacitance between the antenna element of a loading
element without self-resonance at a desired resonance frequency and each element.
In addition, it is possible to flexibly adjust each resonance frequency and obtain
the antenna device in which double to quadruple resonance is possible according to
design conditions through selection (a constant change or the like) of the antenna
element and the first to fourth passive elements to be connected to the first to fourth
connectors. As described above, because it is possible to flexibly adjust each resonance
frequency in one substrate for the antenna device according to the antenna configuration,
replacement of the resonance frequency is possible and an adjustment position based
on a passive element or the like can change according to the use or device. Also,
a bandwidth can be adjusted according to settings of a length and width of each element
and each stray capacitance.
[0012] In addition, a design is possible within a plane of the substrate main body and thickness
reduction is possible as compared with the case in which the conventional dielectric
block or resin-molded body or the like is used and size reduction and high performance
are also enabled by selecting the antenna element which is the dielectric antenna.
In addition, cost according to a metal mold, a design change, or the like is unnecessary
and low cost can be implemented.
[0013] The antenna-device substrate according to a second present invention comprises, in
the first present invention, a first ground connector having a base end connected
to the ground plane and a distal end connected to a base end side of the first element
closer than a connection portion of the first element with the second element; a second
ground connector having a base end separated from a position at which the first ground
connector is connected and connected to the ground plane and a distal end connected
to a base end side of the third element closer than a connection portion of the third
element with the fourth element; and a connection pattern extending by connecting
a distal end side of the first element further than a connection portion of the first
element with the first ground connector and a distal end side of the third element
further than a connection portion of the third element with the second ground connector,
wherein an annular opening pattern portion among the connection pattern, the first
element, and the third element is formed in the vicinity of the power feeding point.
[0014] Because the annular opening pattern portion among the connection pattern, the first
element, and the third element is formed in the vicinity of the power feeding point
in the antenna-device substrate, it is possible to reduce a bad influence from a capacitance
occurring between peripheral components by a capacitance occurring within the opening
pattern portion and implement high performance for each element. That is, the opening
pattern portion can effectively make a flow of a high-frequency current from the power
feeding point to elements of the side of the first element (including the second element)
and the side of the third element (including the fourth element) with good balance.
In particular, when a distance from a peripheral component is short due to size reduction
or thickness reduction, it is possible to effectively achieve both size reduction
and high performance.
[0015] The antenna-device substrate according to a third present invention is characterized
in that, in the first or second present invention, the first element includes a first
extension portion extending from the power feeding point in one direction along the
ground plane, a second extension portion extending from a distal end of the first
extension portion away from the ground plane, and a third extension portion extending
from a distal end of the second extension portion in a direction along the ground
plane via the first connector and to which the antenna element extending in the same
direction is connected, the second element includes a fourth extension portion extending
from the distal end of the second extension portion in the same direction as that
of the second extension portion via the second connector and a fifth extension portion
extending from a distal end of the fourth extension portion to a side of the antenna
element in a direction along the third extension portion, the third element includes
a sixth extension portion extending from the power feeding point in another direction
along the ground plane, a seventh extension portion extending from a distal end of
the sixth extension portion away from the ground plane via the third connector, and
an eighth extension portion extending from a distal end of the seventh extension portion
to the fourth extension portion in a direction along the ground plane, and the fourth
element includes a ninth extension portion having a distal end connected to the middle
of the seventh extension portion and extending with a gap from the seventh extension
portion in the same direction and a tenth extension portion extending from a distal
end of the ninth extension portion away from the seventh extension portion.
[0016] That is, because the first element has the first to third extension portions, the
second element has the fourth and fifth extension portions, the third element has
the sixth to eighth extension portions, and the fourth element has the ninth extension
portion and the tenth extension portion on the antenna-device substrate, stray capacitance
between the first element and the ground plane, stray capacitance between the antenna
element and the fifth extension portion, stray capacitance between the third extension
portion and the fifth extension portion, stray capacitance between the fifth extension
portion and the eighth extension portion, stray capacitance among the first extension
portion, the sixth extension portion, and the eighth extension portion, stray capacitance
between the seventh extension portion and the ninth extension portion, and stray capacitance
between the tenth extension portion and the ground plane can occur and a high degree
of freedom of adjustment at each resonance frequency can be obtained.
[0017] The antenna-device substrate according to a fourth present invention is characterized
in that, in the third present invention, a base end side closer than a portion opposite
to the antenna element of the fifth extension portion serves as a wide portion formed
to be wider than a distal end side.
[0018] That is, because the base end side closer than the portion opposite to the antenna
element of the fifth extension portion serves as the wide portion formed to be wider
than the distal end side on the antenna-device substrate, it is possible to cause
stray capacitance between the fifth extension portion and the third extension portion
through the wide portion to effectively occur while securing the wide portion without
interference with the antenna element and achieve a broad band and size reduction.
[0019] The antenna-device substrate according to a fifth present invention is characterized
in that, in the third or fourth present invention, the first element includes an eleventh
extension portion extending from a distal end of the third extension portion to the
ground plane and a twelfth extension portion extending from a distal end of the eleventh
extension portion to the first extension portion along the ground plane.
[0020] That is, because the first element has an eleventh extension portion extending from
the distal end of the third extension portion to the ground plane and the twelfth
extension portion extending from the distal end of the eleventh extension portion
to the first extension portion along the ground plane on the antenna-device substrate,
it is possible to cause stray capacitance between the twelfth extension portion and
the third extension portion and stray capacitance between the twelfth extension portion
and the ground plane to occur.
[0021] The antenna-device substrate according to a sixth present invention is characterized
in that, in any one of the third to fifth present inventions, a thirteenth extension
portion extending away from the ground plane is connected to a base end side of the
tenth extension portion.
[0022] That is, because the thirteenth extension portion extending away from the ground
plane is connected to the base end side of the tenth extension portion on the antenna-device
substrate, it is possible to cause stray capacitance between the thirteenth extension
portion and the seventh extension portion to occur and distribute a high-frequency
current away from the ground plane through the thirteenth extension portion. In addition,
because a space between the tenth extension portion and the thirteenth extension portion
is empty, it is possible to secure a space or the like for fixing a screw of the substrate
main body in the empty space.
[0023] The antenna-device substrate according to a seventh present invention is characterized
in that, in any one of the third to sixth present inventions, the eighth extension
portion includes a first rear-surface pattern portion patterned on a rear surface
of the substrate main body connected to a front surface side via a through-hole and
the first rear-surface pattern portion is widely formed toward the ground plane.
[0024] That is, because the eighth extension portion has the first rear-surface pattern
portion patterned on the rear surface of the substrate main body connected to the
front surface side via the through-hole and the first rear-surface pattern portion
is widely formed toward the ground plane on the antenna-device substrate, it is possible
to cause stray capacitance with the fourth extension portion to effectively occur
without interfering with the fourth extension portion. In addition, because the first
rear-surface pattern portion is widely formed toward the ground plane, impedance is
also lower than in the fourth extension portion and an influence of interference can
be reduced according to stray capacitance with the first extension portion and the
eighth extension portion.
[0025] The antenna-device substrate according to an eighth present invention is characterized
in that, in the sixth present invention, the thirteenth extension portion includes
a second rear-surface pattern portion patterned on a rear surface of the substrate
main body connected to a front surface side via a through-hole and the second rear-surface
pattern portion is widely formed toward the ground plane.
[0026] That is, because the thirteenth extension portion has the second rear-surface pattern
portion patterned on the rear surface of the substrate main body connected to the
front surface side via the through-hole and the second rear-surface pattern portion
is widely formed toward the ground plane on the antenna-device substrate, it is possible
to cause stray capacitance with the eighth extension portion or the ground plane by
the pattern arrangement with the tenth extension portion to effectively occur.
[0027] Therefore, it is possible to further achieve both high performance and size reduction
of an antenna without widening an antenna occupancy area according to adaptation of
the first rear-surface pattern portion or the second rear-surface pattern portion.
[0028] The antenna-device substrate according to a ninth present invention is characterized
in that, in the second present invention, a passive element for impedance adjustment
is connected to each of the first ground connector and the second ground connector.
[0029] That is, because the passive element for impedance adjustment is connected to each
of the first ground connector and the second ground connector on the antenna-device
substrate, it is possible to perform impedance adjustment of each frequency band through
a setting of the opening pattern portion and settings of two passive elements for
impedance adjustment.
[0030] According to a tenth present invention, an antenna device comprises: the antenna-device
substrate according to any one of the first to ninth present inventions, wherein the
first passive element, the second passive element, the third passive element, and
the fourth passive element are connected to the first, second, third, and fourth connectors
corresponding thereto.
[0031] That is, because the first passive element, the second passive element, the third
passive element, and the fourth passive element are connected to the first, second,
third, and fourth connectors corresponding thereto on the antenna device, it is possible
to achieve double to quadruple resonance by merely appropriately selecting the first
to fourth passive elements and communication at two to four resonance frequencies
corresponding to each use or device.
[0032] According to an eleventh present invention, an antenna device comprises: the antenna-device
substrate according to any one of the first to ninth present inventions, wherein the
first passive element is connected to the first connector and wherein any one or two
of the second passive element, the third passive element, and the fourth passive element
are connected to the second, third, and fourth connectors corresponding thereto.
[0033] That is, because the first passive element is connected to the first connector and
any one or two of the second passive element, the third passive element, and the fourth
passive element are connected to the second, third, and fourth connectors corresponding
thereto on the antenna device, double resonance in two types or triple resonance in
three types is possible in a state in which any one or two of the second passive element,
the third passive element, and the fourth passive element are not used.
[Advantageous Effects of Invention]
[0034] The present invention accomplishes the following effects.
[0035] That is, because the first to fourth elements extend with gaps from the adjacent
elements and the ground plane so that stray capacitance between adjacent elements
and stray capacitance with the ground plane can occur according to the antenna-device
substrate and the antenna device having the same according to the present invention,
it is possible to perform multiple resonance (double to quadruple resonance). In addition,
it is possible to flexibly adjust each resonance frequency and obtain the antenna
device in which double to quadruple resonance is possible according to a design condition
through selection of the first to fourth passive elements to be connected to the first
to fourth connectors and enable size reduction and high performance.
[0036] Therefore, the antenna-device substrate and the antenna device having the same according
to the present invention can be easily provided with a multiple resonance characteristic
corresponding to various uses or devices and save space.
[Brief Description of Drawings]
[0037]
Fig. 1 is a wiring diagram illustrating an antenna device in an embodiment of an antenna-device
substrate and an antenna device according to the present invention.
Fig. 2 is a wiring diagram illustrating stray capacitance occurring on the antenna
device in this embodiment.
Fig. 3 is a top view and a rear view illustrating the antenna-device substrate in
this embodiment.
Fig. 4 is a top view illustrating the antenna device in this embodiment.
Fig. 5 is a perspective view (a), a top view (b), a front view (c), and a bottom view
(d) illustrating an antenna element in this embodiment.
Fig. 6 is an explanatory diagram illustrating a function of an opening pattern portion
in this embodiment.
Fig. 7 is a graph illustrating a voltage standing wave ratio (VSWR) characteristic
in quadruple resonance in examples of an antenna-device substrate and an antenna device
according to the present invention.
Fig. 8 is graphs illustrating radiation patterns of a 920 MHz band, a 1400 MHz band,
and a 1920 MHz band in an example according to the present invention.
[Description of Embodiments]
[0038] Hereinafter, an embodiment of an antenna device according to the present invention
will be described with reference to Figs. 1 to 6.
[0039] The antenna-device substrate 1 in this embodiment includes an insulating substrate
main body 2, a first element EL1, a second element EL2, a third element EL3, and a
fourth element EL4 patterned by use of metal foils such as copper foils on the substrate
main body 2 and a ground plane GND as illustrated in Figs. 1 to 4.
[0040] Also, a mounting region of a radio frequency (RF) circuit or the like is provided
in the ground plane GND. In addition, the ground plane GND is formed in a similar
pattern corresponding to a front surface on a rear surface as well as the front surface
of the substrate main body 2.
[0041] The first element EL1 extends to have a base end on which a power feeding point FP
is provided in the vicinity of the ground plane GND and have a first connector C1
to which a first passive element P1 is contactable and an antenna element AT of a
dielectric antenna in this order in the middle. Also, in this embodiment, as illustrated
in Figs. 3 and 4, the first passive element P1 is mounted on each of two first connectors
C1 and two first passive elements P1 are connected in series.
[0042] The second element EL2 extends to have a base end connected between the power feeding
point FP of the first element EL1 and the first connector C1 and have a second connector
C2 to which a second passive element P2 is connectable in the middle.
[0043] The third element EL3 extends to have a base end to which the power feeding point
FP is connected and have a third connector C3 to which a third passive element P3
is connectable in the middle. Also, in this embodiment, as illustrated in Figs. 3
and 4, the third passive element P3 is mounted on each of two third connectors C3
and two third passive elements P3 are connected in series.
[0044] The fourth element EL4 extends to have a base end connected between the power feeding
point FP of the third element EL3 and the third connector C3 and have a fourth connector
C4 to which a fourth passive element P4 is connectable in the middle. Also, in this
embodiment, as illustrated in Figs. 3 and 4, the fourth passive element P4 is mounted
on each of two fourth connectors C4 and two fourth passive elements P4 are connected
in series.
[0045] The first passive element P1, the third passive element P3, and the fourth passive
element P4 are used by combining two passive elements, but two passive elements having
the same characteristic may be used or two passive elements having different characteristics
may be used. In addition, one passive element or a combination of three or more passive
elements may be used instead of a combination of two passive elements.
[0046] The first element EL1 has a first extension portion E1 extending from the power feeding
point FP in one direction along the ground plane GND, a second extension portion E2
extending from a distal end of the first extension portion E1 away from the ground
plane GND, and a third extension portion E3 extending from a distal end of the second
extension portion E2 in a direction along the ground plane GND via the first connector
C1 and to which the antenna element AT extending in the same direction is connected.
Also, the direction along the ground plane GND is a direction along an edge side of
an opposite ground plane GND.
[0047] Also, the first extension portion E1 extends away from the ground plane GND after
extending from the power feeding point FP in one direction along the ground plane
GND, further extends in one direction along the ground plane GND, and extends in one
direction along the ground plane GND as a whole while being bent in a crank shape.
[0048] In addition, the first element EL1 has an eleventh extension portion E11 extending
from a distal end of the third extension portion E3 toward the ground plane GND and
a twelfth extension portion E12 extending from a distal end of the eleventh extension
portion E11 toward the first extension portion E1 along the ground plane GND. That
is, the distal end side of the first element EL1 is bent by the eleventh extension
portion E11 and the twelfth extension portion E12. Also, the eleventh extension portion
E11 has a wide rectangular shape.
[0049] The second element EL2 has a fourth extension portion E4 extending from a distal
end of the second extension portion E2 in the same direction as the second extension
portion E2 via the second connector C2 and a fifth extension portion E5 extending
from a distal end of the fourth extension portion E4 to a side of the antenna element
AT in a direction along the third extension portion E3.
[0050] In addition, a base end side closer than a portion opposite to the antenna element
AT of the fifth extension portion E5 serves as a wide portion E5a formed to be wider
than a distal end side.
[0051] The third element EL3 has a sixth extension portion E6 extending from the power feeding
point FP in another direction along the ground plane GND, a seventh extension portion
E7 extending from a distal end of the sixth extension portion E6 away from the ground
plane GND via the third connector C3, and an eighth extension portion E8 extending
from a distal end of the seventh extension portion E7 toward the fourth extension
portion E4 in a direction along the ground plane GND. Also, the sixth extension portion
E6 extends away from the ground plane GND after extending from the power feeding point
FP in the other direction along the ground plane GND, further extends in the other
direction along the ground plane GND, and extends in the other direction along the
ground plane GND as a whole while being bent in the crank shape.
[0052] That is, base end portions (the first extension portion E1 and the sixth extension
portion E6) of the first element EL1 and the third element EL3 are extended in opposite
direction each other from the power feeding point FP.
[0053] The eighth extension portion E8 has a first rear-surface pattern portion R1 patterned
on a rear surface of the substrate main body 2 connected to a front surface side via
a through-hole H, and the first rear-surface pattern portion R1 is widely formed toward
the ground plane GND. Also, the first rear-surface pattern portion R1 is connected
to the eighth extension portion E8 of the front surface side through the through-hole
H on an end portion side of the substrate main body 2.
[0054] The fourth element EL4 has a ninth extension portion E9 having a distal end connected
to the middle of the seventh extension portion E7 and extending with a gap from the
seventh extension portion E7 in the same direction and a tenth extension portion E10
extending from a distal end of the ninth extension portion E9 away from the seventh
extension portion E7.
[0055] In addition, the thirteenth extension portion E13 extending away from the ground
plane GND is connected to a base end side of the tenth extension portion E10.
[0056] The thirteenth extension portion E13 has a second rear-surface pattern portion R2
patterned on a rear surface of the substrate main body 2 connected to the front surface
side via the through-hole H, and the second rear-surface pattern portion R2 is widely
formed toward the ground plane GND. Also, the second rear-surface pattern portion
R2 is connected to the thirteenth extension portion E13 of the front surface side
through the through-hole H on an end portion side of the substrate main body 2.
[0057] In addition, the antenna-device substrate 1 includes a first ground connector G1
having a base end connected to the ground plane GND and a distal end connected to
a base end side of the first element EL1 closer than a connection portion of the first
element EL1 with the second element EL2; a second ground connector G2 having a base
end separated from a position at which the first ground connector G1 is connected
and connected to the ground plane GND and a distal end connected to a base end side
of the third element EL3 closer than a connection portion of the third element EL3
with the fourth element EL4; and a connection pattern L1 extending by connecting a
distal end side of the first element EL1 further than a connection portion of the
first element EL1 with the first ground connector G1 and a distal end side of the
third element EL3 further than a connection portion of the third element EL3 with
the second ground connector G2.
[0058] In addition, an annular opening pattern portion S1 among the connection pattern L1,
the first element EL 1, and the third element EL3 is formed in the vicinity of the
power feeding point FP. That is, the opening pattern portion S1 having an approximately
rectangular shape that extends along the ground plane GND is configured by parts of
the first extension portion E1 and the sixth extension portions E6 bent in the crank
shape and the connection pattern L1.
[0059] A fifth passive element P5 which is a passive element for impedance adjustment is
connected to the first ground connector G1 and a sixth passive element P6 which is
a passive element for impedance adjustment is connected to the second ground connector
G2. Also, in this embodiment, the ground plane GND and the first element EL1 are directly
connected by only the fifth passive element P5 and the fifth passive element P5 itself
functions as the first ground connector G1. In addition, the ground plane GND and
the third element EL3 are directly connected by only the sixth passive element P6,
and the sixth passive element P6 itself functions as the second ground connector G2.
[0060] The substrate main body 2 is a general printed circuit board. In this embodiment,
a main body of the printed circuit board formed of a rectangular glass epoxy resin
or the like is adopted. Also, dimensions of the substrate main body 2 of this embodiment
are a longitudinal direction: 110 mm, a lateral direction: 52 mm, and a thickness:
1.0 mm. In addition, dimensions of the antenna region (including a part of the ground
plane GND below the fourth element EL4) on the substrate main body 2 are a longitudinal
direction of the substrate main body 2: 11 mm and a lateral direction of the substrate
main body 2: 35 mm.
[0061] The power feeding point FP is connected to the power feeding point of a high-frequency
circuit (not illustrated) via a power feeding means such as a coaxial cable. As the
power feeding means, various structures such as a coaxial cable, a connector such
as a receptacle, a connection structure having a contact point of a plate spring shape,
a connection structure having a contact point of a pin probe shape or a pin shape,
a connection structure using a soldering land, etc. can be adopted.
[0062] For example, when the coaxial cable is adopted as the power feeding means, a ground
line of the coaxial cable is connected to a base end side of the ground plane GND
and a core wire of the coaxial cable is connected to the power feeding point FP.
[0063] The antenna element AT is a loading element without self-resonance at a desired resonance
frequency, and, for example, is a chip antenna in which a conductor pattern 102 is
formed, for example, of Ag, on the surface of a dielectric block 101 such as a ceramic
as illustrated in Fig. 5. For the antenna element AT, according to a setting such
as a resonance frequency, elements different in a length, a width, a conductor pattern
102, etc. thereof may be selected or the same element may be selected. Also, the dimensions
of the antenna element AT of this embodiment are a width: 10.5 mm, a depth: 3.0 mm,
and a height: 0.8 mm.
[0064] For example, inductors, condensers, or resistors are adopted for the first passive
element P1 to the sixth passive element P6.
[0065] On the antenna-device substrate 1 of this embodiment, the elements from the first
element EL1 to the fourth element EL4 extend with gaps from the adjacent elements
and the ground plane GND so that stray capacitance between adjacent elements and stray
capacitance with the ground plane GND can occur.
[0066] That is, as illustrated in Fig. 2, stray capacitance Ca between the twelfth extension
portion E12 and the ground plane GND, stray capacitance Cb between the antenna element
AT (third extension portion E3) and the twelfth extension portion E12, stray capacitance
Cc between the antenna element AT and the fifth extension portion E5, stray capacitance
Cf between the third extension portion E3 and the fifth extension portion E5, stray
capacitance Cg between the fifth extension portion E5 and the eighth extension portion
E8, stray capacitance Ch between the opening pattern portion S1 (the first extension
portion E1 and the sixth extension portion E6) and the eighth extension portion E8,
stray capacitance Ci between the eighth extension portion E8 and the thirteenth extension
portion E13, stray capacitance Cj between the seventh extension portion E7 and the
ninth extension portion E9, and stray capacitance Ck between the tenth extension portion
E10 and the ground plane GND can occur. In addition, a capacitance Cd is also generated
by the opening pattern portion S1.
[0067] As illustrated in Fig. 4, the antenna device 10 of this embodiment includes the antenna-device
substrate 1, and the first passive element P1, the second passive element P2, the
third passive element P3, and the fourth passive element P4 are connected to the first
connector C1, the second connector C2, the third connector C3, and the fourth connector
C4 corresponding thereto, respectively.
[0068] Next, a resonance frequency of the antenna device 10 of this embodiment will be described
with reference to Fig. 7.
[0069] The antenna device 10 of this embodiment, as illustrated in Fig. 7, has multiple
resonance frequencies at four frequencies, i.e., a first resonance frequency f1, a
second resonance frequency f2, a third resonance frequency f3, and a fourth resonance
frequency f4.
[0070] The first resonance frequency f1 is that of a low frequency band (for example, a
920 MHz band) among the four resonance frequencies, and is determined by the antenna
element AT and a length of the first element EL1 (the first extension portion E1,
the second extension portion E2, the eleventh extension portion E11, and the twelfth
extension portion E12).
[0071] In addition, the bandwidth widening of the first resonance frequency f1 is determined
by lengths and widths of the twelfth extension portion E12, the eleventh extension
portion E11, and the third extension portion E3.
[0072] In addition, impedance at the first resonance frequency f1 is determined by the stray
capacitances Ca to Cd.
[0073] Further, the final adjustment of the first resonance frequency f1 can be flexibly
adjusted using the first passive element P1.
[0074] Therefore, the first resonance frequency f1 is mainly adjusted by a part surrounded
by a broken line A1 in Fig. 2.
[0075] As described above, for the first resonance frequency f1, the resonance frequency,
the bandwidth, and the impedance can be flexibly adjusted according to settings of
the length and width of the first element EL1, the first passive element P1, the antenna
element AT, and each stray capacitance described above.
[0076] Next, the third resonance frequency f3 is determined by lengths of the first extension
portion E1, the second extension portion E2, the fourth extension portion E4, and
the fifth extension portion E5.
[0077] In addition, the bandwidth widening of the third resonance frequency f3 is determined
by lengths and widths of the first extension portion E1, the second extension portion
E2, the fourth extension portion E4, and the fifth extension portion E5.
[0078] In addition, the impedance at the third resonance frequency f3 is determined by the
stray capacitances Cd, Cc, Cf, and Cg.
[0079] Further, the final adjustment of the third resonance frequency f3 can be flexibly
adjusted using the second passive element P2.
[0080] Therefore, the third resonance frequency f3 is mainly adjusted by a part surrounded
by a dash-dot line A3 in Fig. 2.
[0081] As described above, for the third resonance frequency f3, the resonance frequency,
the bandwidth, and the impedance can be flexibly adjusted according to settings of
the length and width of the first extension portion E1, the second extension portion
E2, and the second element EL2, the second passive element P2, and each stray capacitance
described above.
[0082] Next, the fourth resonance frequency f4 is determined by lengths of the eighth extension
portion E8 and the seventh extension portion E7.
[0083] In addition, the bandwidth widening of the fourth resonance frequency f4 is determined
by lengths and widths of the eighth extension portion E8 and the seventh extension
portion E7.
[0084] In addition, the impedance at the fourth resonance frequency f4 is determined by
the stray capacitances Cd, Cg, Ch, and Ci.
[0085] Further, the final adjustment of the fourth resonance frequency f4 can be flexibly
adjusted using the third passive element P3.
[0086] Therefore, the fourth resonance frequency f4 is mainly adjusted by a part surrounded
by a dash-double-dot line A4 in Fig. 2.
[0087] As described above, for the fourth resonance frequency f4, the resonance frequency,
the bandwidth, and the impedance can be flexibly adjusted according to settings of
the length and width of the third element EL3 (the seventh extension portion E7 and
the eighth extension portion E8), the third passive element P3, and each stray capacitance
described above.
[0088] Next, the second resonance frequency f2 is determined by lengths of the seventh extension
portion E7, the thirteenth extension portion E13, the tenth extension portion E10,
and the ninth extension portion E9.
[0089] In addition, the bandwidth widening of the second resonance frequency f2 is determined
by lengths and widths of the seventh extension portion E7, the thirteenth extension
portion E13, the tenth extension portion E10, and the ninth extension portion E9.
[0090] In addition, the impedance at the second resonance frequency f2 is determined by
the stray capacitances Cd, Ci, Cj, and Ck.
[0091] Further, the final adjustment of the second resonance frequency f2 can be flexibly
adjusted using the fourth passive element P4.
[0092] Therefore, the second resonance frequency f2 is mainly adjusted by a part surrounded
by a broken line A2 in Fig. 2.
[0093] As described above, for the second resonance frequency f2, the resonance frequency,
the bandwidth, and the impedance can be flexibly adjusted according to settings of
lengths and widths of the seventh extension portion E7, the thirteenth extension portion
E13, the tenth extension portion E10, and the ninth extension portion E9, the fourth
passive element P4, and each stray capacitance described above.
[0094] Also, for each resonance frequency described above, it is possible to flexibly perform
the final impedance adjustment using the fifth passive element P5 and the sixth passive
element P6 which are passive elements for impedance adjustment.
[0095] Next, the effect of the opening pattern portion S1 will be described.
[0096] The opening pattern portion S1 is provided in the vicinity of the power feeding point
FP in this embodiment, and a high-frequency current can effectively flow from the
power feeding point FP to the left and right elements according to the opening pattern
portion S1.
[0097] That is, when there is no opening pattern portion S1, the flow to the antenna elements
(the third element EL3 and the fourth element EL4) of the right side of the drawing
in the flow of the high-frequency current from the power feeding point FP is smooth,
but a capacitance with the element from the power feeding point FP occurs in the flow
to the left side as illustrated in (b) of Fig. 6. Even in the case of wiring illustrated
in (c) of Fig. 6, the flow to the left side is similarly smooth, but the capacitance
with the element from the power feeding point FP occurs in the flow to the right side.
[0098] As a result, two antenna elements are provided in each of the left and right directions
and a degree of influence is also different, leading to performance degradation.
[0099] In addition, when there is no opening pattern portion S1 and a connection is achieved
in the center as illustrated in (d) of Fig. 6, similar capacitances occur in both
the left and right and significant performance degradation occurs.
[0100] Further, as illustrated in (e) of Fig. 6, in the case of a pattern in which a part
of the opening pattern portion S1 becomes a wide pattern without an opening and a
connection is achieved in large area in the center, a high-frequency current of each
element is not problematic, but performance degradation increases because the area
is large by mounting a component around the antenna.
[0101] In particular, with size reduction or thickness reduction, a distance from a peripheral
component become short and significant performance degradation further occurs.
[0102] Therefore, as illustrated in (a) of Fig. 6, by providing the opening pattern portion
S1 as in the present invention, a bad influence from a capacitance occurring between
peripheral components is reduced by a capacitance within the opening pattern portion
S1, a high-frequency current flowing through each antenna element can efficiently
flow, and it is possible to implement both size reduction and high performance.
[0103] Next, a first rear-surface pattern portion R1 and a second rear-surface pattern portion
R2 will be described.
[0104] First, in the first rear-surface pattern portion R1, stray capacitance for the fourth
extension portion E4 and the opening pattern portion S1 occurs in the surface.
[0105] Because the stray capacitance occurs in the fourth extension portion E4 when the
first rear-surface pattern portion R1 is designed, the stray capacitance is not effectively
used according to a thickness of the substrate main body 2 in an extension direction
of the fourth extension portion E4 and the fourth extension portion E4 may be interfered
with.
[0106] In regard to this, impedance in any direction toward the opening pattern portion
S1 is lower than that of the fourth extension portion E4 and an influence of interference
is small according to a capacitance of the side of the opening pattern portion S1.
Thus, for the first rear-surface pattern portion R1, a design in which a width corresponding
to the eighth extension portion E8 is set as a maximum width and the first rear-surface
pattern portion R1 extends from an end portion side of the substrate main body 2 in
an extension direction of the fourth extension portion E4 is effective.
[0107] In addition, in the second rear-surface pattern portion R2, stray capacitance with
the eighth extension portion E8 or the ground plane GND by the pattern arrangement
with the tenth extension portion E10 occurs for the thirteenth extension portion E13.
Thus, for the second rear-surface pattern portion R2, as in the first rear-surface
pattern portion R1, a design in which a width corresponding to the thirteenth extension
portion E13 is set as a maximum width and the second rear-surface pattern portion
R2 extends from an end portion side of the substrate main body 2 in a direction toward
the tenth extension portion E10 is effective.
[0108] Next, the tenth extension portion E10 and the thirteenth extension portion E13 will
be described.
[0109] The thirteenth extension portion E13 is combined with the tenth extension portion
E10 and has an orthogonal pattern arrangement. When this thirteen extension portion
E13 is patterned in only the horizontal direction (the extension direction of the
tenth extension portion E10), a degree of freedom of the design is low because it
is necessary to design the stray capacitance with the eighth extension portion E8
in consideration of the stray capacitance with the ground plane GND. Thus, further
size reduction is difficult.
[0110] Therefore, by disposing the tenth extension portion E10 which uses the stray capacitance
with the ground plane GND and designing the thirteenth extension portion E13 in a
distribution pattern which uses the stray capacitance with the eighth extension portion
E8, a high-frequency current, which flows through each antenna element, is also distributed
and each stray capacitance can be effectively designed. In addition, there is an advantage
in that the ground plane GND can be disposed up to the vicinity of the tenth extension
portion E10 and other parts (a button/switch, a microphone, a flexible printed circuit
(FPC), etc.) for use in the device can be mounted, leading to size reduction of the
device.
[0111] Next, the fifth extension portion E5 will be described.
[0112] The fifth extension portion E5 has a pattern arrangement using stray capacitance
with the antenna element AT, but it is necessary to reduce an antenna region when
the entire size reduction is considered and the arrangements of the fifth extension
portion E5 and the antenna element AT are important.
[0113] It is ideal to widely design a width of the fifth extension portion E5 because it
leads to a wider bandwidth, but compatibility with size reduction may be difficult
due to an antenna region. Therefore, it is desirable to finely design the width of
the fifth extension portion E5 and design the fifth extension portion E5 at a position
close to the end portion of the substrate main body 2.
[0114] Further, it is preferable to designate the wide portion E5a by widening a pattern
width of the side of the fifth extension portion E5 of a part in which stray capacitance
Cf between the third extension portion E3 and the fifth extension portion E5 occurs
and form an efficient pattern arrangement. The wide portion E5a has a chamfered shape
(a triangular shape or a trapezoidal shape) rather than a square shape in consideration
of an influence of the stray capacitance Cc between the antenna element AT and the
fifth extension portion E5, so that it is possible to control a high-frequency current
flowing through the fifth extension portion E5 while effectively using the stray capacitance.
[0115] Because the elements from the first element EL1 to the fourth element EL4 extend
with gaps from the adjacent elements and the ground plane GND so that stray capacitance
between adjacent elements and stray capacitance with the ground plane GND can occur
in the antenna-device substrate 1 of this embodiment, the substrate 1 can be provided
with a multiple resonance (double to quadruple resonance) by effectively employing
the stray capacitance between the antenna element AT of a loading element without
self-resonance at a desired resonance frequency and each element.
[0116] In addition, it is possible to flexibly adjust each resonance frequency and obtain
the antenna device 10 in which double to quadruple resonance is possible according
to design conditions through selection (a constant change or the like) of the antenna
element AT and the first to fourth passive elements P1 to P4 to be connected to the
first to fourth connectors C1 to C4. As described above, because it is possible to
flexibly adjust each resonance frequency in one antenna-device substrate 1 according
to the antenna configuration, the replacement of the resonance frequency is possible
and an adjustment position based on a passive element or the like can change according
to the use or device.
[0117] In addition, a design is possible within a plane of the substrate main body 2 and
thickness reduction is possible as compared with the case in which the conventional
dielectric block or resin molded body or the like is used and size reduction and high
performance are also enabled by selecting the antenna element AT which is the dielectric
antenna. In addition, cost according to a mold, a design change, or the like is unnecessary
and low cost can be implemented.
[0118] Further, because the annular opening pattern portion S1 among the connection pattern
L1, the first element EL1, and the third element EL3 is formed in the vicinity of
the power feeding point FP, it is possible to reduce a bad influence from a capacitance
occurring between peripheral components by the capacitance Cd occurring within the
opening pattern portion S1 and implement high performance for each element.
[0119] In addition, because a base end side closer than a portion opposite to the antenna
element AT of the fifth extension portion E5 serves as the wide portion E5a formed
to be wider than a distal end side, it is possible to cause stray capacitance between
the fifth extension portion E5 and the third extension portion E3 to effectively occur
through the wide portion E5a while securing the wide portion E5a without interference
with the antenna element AT and achieve a broad band and size reduction.
[0120] In addition, because the thirteenth extension portion E13 extending away from the
ground plane GND is connected to the base end side of the tenth extension portion
E10, it is possible to cause stray capacitance Ci between the thirteenth extension
portion E13 and the seventh extension portion E7 to occur and distribute a high-frequency
current away from the ground plane GND through the thirteenth extension portion E13.
In addition, because a space between the tenth extension portion E10 and the thirteenth
extension portion E13 is empty, it is possible to secure a space or the like for fixing
a screw of the substrate main body 2 in the empty space.
[0121] In addition, because the eighth extension portion E8 has the first rear-surface pattern
portion R1 connected to the front surface side via the through-hole H and patterned
on a rear surface of the substrate main body 2, and the first rear-surface pattern
portion R1 is widely formed toward the ground plane GND, it is possible to cause stray
capacitance with the fourth extension portion E4 to effectively occur without interfering
with the fourth extension portion E4. In addition, because the first rear-surface
pattern portion R1 is widely formed toward the ground plane GND, impedance is also
lower than with the fourth extension portion E4 and an influence of interference can
also be reduced according to the stray capacitance Ch with the opening pattern portion
S1 (the first extension portion E1 and the eighth extension portion E8).
[0122] In addition, because the thirteenth extension portion E13 has the second rear-surface
pattern portion R2 connected to the front surface side via the through-hole H and
patterned on the rear surface of the substrate main body 2, and the second rear-surface
pattern portion R2 is widely formed toward the ground plane GND, it is possible to
cause stray capacitance with the eighth extension portion E8 or stray capacitance
with the ground plane GND by the pattern arrangement with the tenth extension portion
E10 to effectively occur. Therefore, it is possible to further achieve both high performance
and size reduction of an antenna without widening an antenna occupancy area by adopting
the first rear-surface pattern portion R1 or the second rear-surface pattern portion
R2.
[0123] In addition, because passive elements (the fifth passive element P5 and the sixth
passive element P6) for impedance adjustment are connected to the first ground connector
G1 and the second ground connector G2 respectively, it is possible to perform impedance
adjustment of each frequency band through a setting of the opening pattern portion
S1 and settings of two passive elements for impedance adjustment.
[0124] Accordingly, because the first passive element P1, the second passive element P2,
the third passive element P3, and the fourth passive element P4 are connected to the
first connector C1, the second connector C2, the third connector C3, and the fourth
connector C4 corresponding thereto in the antenna device 10 of this embodiment, it
is possible to achieve double to quadruple resonances by merely appropriately selecting
the first to fourth passive elements P1 to P4 and communication at two to four resonance
frequencies corresponding to each use or device.
[Examples]
[0125] Next, for an example produced based on an antenna-device substrate and an antenna
device of this embodiment, a result of measuring a VSWR characteristic (voltage standing
wave ratio) and a radiation pattern in quadruple resonance at each resonance frequency
will be described with reference to Figs. 7 and 8.
[0126] Also, as the passive elements, two first passive elements P1: an inductor of 3.3
nH and an inductor of 10 nH (an inductor of 13 nH in total), a second passive element
P2: 8.2 nH, a third passive element P3: an inductor of 4.7 nH and an inductor of 5.6
nH (an inductor of 10 nH in total), and two fourth passive elements P4: an inductor
of 5.6 nH and an inductor of 12 nH (an inductor of 18 nH in total) were used. In addition,
a condenser of 0.5 pF was used as the fifth passive element P5 and an inductor of
8.2 nH was used as the sixth passive element P6.
[0127] As a result, a good VSWR characteristic was obtained as illustrated in Fig. 7 at
resonance frequencies from the first resonance frequency f1 to the fourth resonance
frequency f4 in the example of the present invention.
[0128] In addition, for measurement of a radiation pattern, a direction toward the ground
plane GND in which the second extension portion E2 extended was designated as an X
direction, a direction opposite to the extension direction of the third extension
portion E3 was designated as a Y direction, and a direction perpendicular to the front
surface of the substrate main body 2 was designated as a Z direction. At this time,
vertical polarization, horizontal polarization, and power gain for the ZX plane were
measured.
[0129]
- (a) of Fig. 8 illustrates a radiation pattern (ZX plane) at a first resonance frequency
f1 of a 920 MHz band and an average power gain is -5.1 dBi.
- (b) of Fig. 8 illustrates a radiation pattern (ZX plane) at a second resonance frequency
f2 of a 1400 MHz band and an average power gain is -1.9 dBi.
- (c) of Fig. 8 illustrates a radiation pattern (ZX plane) at a fourth resonance frequency
f4 of a 1920 MHz band and an average power gain is -0.8 dBi.
[0130] Also, the present invention is not limited to the above-described embodiments and
examples, but various changes may be made without departing from the subject matter
of the present invention.
[0131] For example, in the above-described embodiment, an antenna element is provided in
the first element, but the antenna element may also be provided in another element.
In this case, it is possible to shorten the length of the element according to the
antenna element and the present invention is preferable when an antenna occupancy
area is narrowed or the like. For example, the antenna element may be connected to
the fifth extension portion, the eighth extension portion, the thirteenth extension
portion, and the tenth extension portion.
[0132] In addition, it is possible to flexibly change and replace a frequency band to be
used for an antenna element (an element other than the first element) outside a lowest
frequency band using the antenna element.
[0133] Further, a maximum of quadruple resonance is implemented in the present invention,
but it is possible to cope with double or triple resonance according to presence and
absence of each passive element for frequency bands other than a lowest frequency
band using the antenna element.
[0134] That is, it is possible to arbitrarily perform double or triple resonance by connecting
any one or two of the second passive element, the third passive element, and the fourth
passive element to the second connector, the third connector, and the fourth connector
corresponding thereto.
[Reference Signs List]
[0135]
1 Antenna-device substrate
2 Substrate main body
10 Antenna device
AT Antenna element
C1 First connector
C2 Second connector
C3 Third connector
C4 Fourth connector
E1 First extension portion
E2 Second extension portion
E3 Third extension portion
E4 Fourth extension portion
E5 Fifth extension portion
E6 Sixth extension portion
E7 Seventh extension portion
E8 Eighth extension portion
E9 Ninth extension portion
E10 Tenth extension portion
E11 Eleventh extension portion
E12 Twelfth extension portion
E13 Thirteenth extension portion
EL1 First element
EL2 Second element
EL3 Third element
EL4 Fourth element
G1 First ground connector
G2 Second ground connector
GND Ground plane
H Through-hole
L1 Connection pattern
P1 First passive element
P2 Second passive element
P3 Third passive element
P4 Fourth passive element
P5 Fifth passive element (passive element for impedance adjustment)
P6 Sixth passive element (passive element for impedance adjustment)
FP Power feeding point
R1 First rear-surface pattern portion
R2 Second rear-surface pattern portion
S1 Opening pattern portion