JP2013074508A - Antenna feeder circuit and antenna having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna feeder circuit excellent in performance and manufacturing efficiency, and an antenna having the same.SOLUTION: An antenna feeder circuit 10 includes: a dielectric substrate 11; phase difference feeder lines 13, 14, each formed of a conductor on the dielectric substrate, for phase difference feeding to first antennas (1, 2) and second antennas (3, 4); and a balun 12 formed of a conductor on the dielectric substrate 11 and electrically connected to the phase difference feeder lines 13, 14. The balun and the phase difference feeder lines are formed of tabular-shaped conductors on the identical dielectric substrate. This can reduce the number of components in the antenna feeder circuit. Further, a factor producing a varied characteristic of the balun can be eliminated. Accordingly, a stable characteristic of the antenna feeder circuit can be obtained.

Description

  The present invention relates to an antenna feeding circuit and an antenna including the antenna feeding circuit.

  FIG. 26 is a diagram schematically showing a configuration of a conventional antenna feeding circuit. Referring to FIG. 26, the antenna feeding circuit is connected to a dipole antenna composed of radiating elements 101 and 102 and a dipole antenna composed of radiating elements 103 and 104. The antenna feeding circuit includes phase difference feeding lines 201 and 202 and a balun 301.

  The phase difference feeders 201 and 202 electrically connect two dipole antennas. The phase difference feeder 201 is electrically connected to the radiating elements 101 and 103, and the phase difference feeder 202 is electrically connected to the radiating elements 102 and 104. The balun 301 is electrically connected to a coaxial cable (not shown) and the phase difference feeders 201 and 202.

  FIG. 27 is an image diagram of the balun 301 shown in FIG. FIG. 28 is an equivalent circuit diagram of the balun 301 shown in FIG. Referring to FIGS. 27 and 28, balun 301 includes a ferrite eyeglass core 65 and a pair of insulated conductors 66 and 67. The insulated conductors 66 and 67 are wound around the eyeglass core 65. As shown in FIG. 28, one end of the insulated conducting wire 67 is electrically connected to the terminal 63 on the antenna side on the phase difference feeding line 202 side, and the other end of the insulated conducting wire 67 is electrically connected to the terminal 68 on the coaxial cable side. It is connected to the. One end of the insulated conductor 66 is electrically connected to the terminal 64 on the phase difference feeder 201 side, and the other end of the insulated conductor 66 is electrically connected to the terminal 69 on the coaxial cable side.

  The coaxial cable 110 includes an inner conductor 111 and an outer conductor (braided wire) 112, and the inner conductor 111 and the outer conductor 112 are insulated by an insulator 113. The inner conductor 111 is electrically connected to the terminal 68 of the balun 301, and the outer conductor 112 is electrically connected to the terminal 69 of the balun 301. The balun 301 performs impedance conversion and balance-unbalance conversion when connecting a coaxial cable (unbalanced) having a characteristic impedance of 75Ω (or 50Ω) and a dipole antenna (balanced) having a characteristic impedance of 300Ω. .

  When the balun 301 shown in FIG. 27 is used, there are problems as described below. First, in order to manufacture a balun, a process for winding an insulated lead wire around an eyeglass core is required. For this reason, performance may not be stable every time a balun is manufactured. Furthermore, when installing a balun, the balun characteristics may differ depending on how the insulated conductor is routed. That is, a conventional balun using a spectacle core has problems in terms of ease of manufacture and characteristics.

  Japanese Unexamined Patent Publication No. 64-89701 (Patent Document 1) discloses a balun device formed on a substrate. The balun device is closely arranged on the inner conductor of the meandering half-wave line, the comb-shaped outer conductor closely arranged on one side of the inner conductor, and the other side of the inner conductor. And a comb-shaped shield conductor. The inner conductor, the outer conductor and the shield conductor are formed on the same main surface of the substrate.

JP-A 64-89701

  As described above, since the spectacles core balun is used in the conventional antenna feeding circuit, the characteristics fluctuate due to the wiring. In addition, since the number of balun parts is increased because the balun is manufactured using the core and the wire, the number of parts of the antenna feeding circuit is increased as a result. Furthermore, an operation for mounting the glasses core balun on the antenna feeding circuit is necessary.

  According to Japanese Unexamined Patent Publication No. 64-89701 (Patent Document 1), only a balun is formed on a substrate. Therefore, in order to realize the antenna feeding circuit, it is necessary to connect components other than the balun such as a feeding line to the balun. Furthermore, since the balun and the feeder line must be formed separately, the number of parts increases.

  An object of the present invention is to provide an antenna feeding circuit excellent in performance and manufacturing efficiency, and an antenna including the feeding circuit.

  An antenna feeding circuit according to an aspect of the present invention includes a dielectric substrate and a conductor, each of which is formed on the dielectric substrate by a conductor, and a first and second feeding lines for performing phase difference feeding to two antennas, and a conductor. And a balun formed on the dielectric substrate and electrically connected to the first and second feeder lines.

  Preferably, the antenna power supply circuit further includes a capacitor electrically connected between the first power supply line and the second power supply line.

  Preferably, the dielectric substrate has a first main surface and a second main surface located on the opposite side to the first main surface. The capacitor includes a first electrode disposed on the first main surface and a second electrode disposed on the second main surface so as to face the first electrode.

  Preferably, the capacitor includes first and second electrodes. The first and second electrodes are arranged to face each other on the same main surface of the dielectric substrate.

Preferably, the balun is a split balun.
Preferably, the balun is formed on one of the two main surfaces of the dielectric substrate. The first and second feeder lines are formed on the other of the two main surfaces of the dielectric substrate.

  Preferably, the antenna feeding circuit further includes third and fourth feeding lines for connecting the balun to the inner conductor and the outer conductor of the coaxial line. The third and fourth feeder lines are formed on the same main surface of the dielectric substrate. Each of the third and fourth power supply lines is configured to project from one of the third and fourth power supply lines to the other to reduce the distance between the third power supply line and the fourth power supply line. Having a projected portion.

  Preferably, the balun is formed in a comb-teeth shape, and is formed in a comb-teeth shape along the first conductor outside the first conductor and the first conductor electrically connected to the inner conductor of the coaxial line. A second conductor having a plurality of bent portions, a comb positioned along the first conductor on the outer side of the first conductor, located on the opposite side of the second conductor with respect to the first conductor And a third conductor having a plurality of bent portions by being formed in a tooth shape. One end of the second conductor is connected to the first conductor. The third conductor is connected to the second conductor. Of the plurality of bent portions of the second conductor, the line width of the bent portion that is at least closest to the inner conductor is smaller than the line width of the smallest portion of the other portion of the second conductor.

  Preferably, the antenna feeding circuit further includes a DC cut capacitor inserted in a signal path electrically connected to the inner conductor of the coaxial line.

  An antenna according to another aspect of the present invention includes any one of the antenna feeding circuits described above and first and second radiating elements connected to first and second feeding lines of the antenna feeding circuit, respectively.

  According to the present invention, it is possible to provide an antenna feeding circuit that is excellent in performance and manufacturing efficiency and also in cost, and an antenna including the feeding circuit.

It is the schematic of the antenna carrying the antenna electric power feeding circuit which concerns on embodiment of this invention. 1 is a diagram schematically showing an antenna feeding circuit according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining a phase difference feed line included in the antenna feed circuit according to the first embodiment. 1 is a diagram schematically illustrating an antenna power feeding circuit according to a first embodiment. It is a schematic diagram of the split balun shown in FIG. FIG. 6 is an equivalent circuit diagram of the split balun shown in FIG. 5. 6 is a schematic diagram of an antenna power feeding circuit according to Embodiment 2. FIG. It is a figure for demonstrating the pattern capacitor | condenser shown in FIG. It is the figure which showed the frequency characteristic of the gain of 14 element antenna which has an antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of VSWR (voltage standing wave ratio) of 14 element antenna which has an antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of the front-back ratio of 14 element antenna which has an antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of the half value width of the 14 element antenna which has the antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of the gain of the 20 element antenna which has the antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of VSWR (voltage standing wave ratio) of the 20 element antenna which has the antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of the front-back ratio of the 20 element antenna which has the antenna electric power feeding circuit which concerns on Embodiment 2. FIG. It is the figure which showed the frequency characteristic of the half value width of the 20 element antenna which has an antenna electric power feeding circuit which concerns on Embodiment 2. FIG. 6 is a schematic diagram of an antenna power feeding circuit according to Embodiment 3. FIG. It is the figure which showed the other example of arrangement | positioning of a pattern capacitor. It is the figure which showed the modification of Embodiment 2 and Embodiment 3. FIG. 6 is a schematic diagram of an antenna power feeding circuit according to Embodiment 4. FIG. It is the figure which showed the structural example of the antenna electric power feeding circuit which mounted F seat type terminal. FIG. 10 is a schematic diagram of an antenna power feeding circuit according to a fifth embodiment. It is an enlarged view of the lightning protection circuit 35 shown in FIG. FIG. 10 is a diagram illustrating another configuration example of the antenna feeding circuit according to the fifth embodiment. It is an enlarged view of the area | region 12E shown in FIG. It is the figure which showed schematically the structure of the conventional antenna electric power feeding circuit. It is an image figure of the balun 301 shown in FIG. FIG. 28 is an equivalent circuit diagram of the balun 301 shown in FIG. 27.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of an antenna equipped with an antenna feeding circuit according to an embodiment of the present invention. Referring to FIG. 1, an antenna 100 includes radiating elements 1 to 4 and a power feeding unit 5 incorporating an antenna power feeding circuit. The radiating elements 1 and 2 constitute a half-wave dipole antenna. Similarly, the radiating elements 3 and 4 constitute a half-wave dipole antenna. The antenna 100 is a phase difference feeding antenna configured by two dipole antennas. It is also possible to configure a Yagi antenna by adding at least one of a director and a reflector to the antenna 100.

  In this embodiment, the two dipole antennas are configured so that radio waves in the frequency band (about 470 to about 710 MHz) of Japanese UHF television broadcasting can be suitably received.

Next, embodiments of the antenna feeding circuit will be described in detail with reference to the drawings.
[Embodiment 1]
FIG. 2 is a diagram schematically showing the antenna feeding circuit according to the first embodiment. Referring to FIG. 2, power supply unit 5 includes an antenna power supply circuit 10 and connection units 1 </ b> A to 4 </ b> A.

  The antenna feeding circuit 10 includes a dielectric substrate 11 and a balun (balanced-unbalanced converter) 12. The balun 12 is formed on the main surface 11A of the dielectric substrate 11 by a flat conductor. The phase difference feeders 13 and 14 are flat conductors and are formed on the main surface of the dielectric substrate 11 opposite to the main surface 11A on which the balun 12 is formed. The balun 12 and the phase difference feed lines 13 and 14 are electrically connected by feed lines 15 and 16 and electrodes 17 and 18. The feeder lines 15 and 16 are flat conductors and are formed on the main surface 11 </ b> A of the dielectric substrate 11 together with the balun 12. “Plate shape” means a shape in which the length in the direction perpendicular to the main surface of the dielectric substrate is smaller than the length in the direction parallel to the main surface of the dielectric substrate. For example, the flat conductor is a conductor pattern formed of a metal foil. However, the shape of the conductor is not limited to a flat plate shape as long as it can be formed on the main surface of the dielectric substrate.

  Furthermore, conductor patterns 31 and 32 for electrically connecting a coaxial cable (not shown) and the balun 12 are formed on the dielectric substrate 11. The conductor pattern formed on the dielectric substrate is also a “flat conductor”.

  FIG. 3 is a diagram for explaining a phase difference feeding line included in the antenna feeding circuit according to the first embodiment. Referring to FIGS. 2 and 3, phase difference feeders 13 and 14 are formed on the other main surface 11 </ b> B of dielectric substrate 11. One end of the phase difference feed line 13 is electrically connected to the feed line 15 by an electrode 17 formed through the dielectric substrate 11. One end of the phase difference feed line 14 is electrically connected to the feed line 16 by an electrode 18 formed so as to penetrate the dielectric substrate 11.

  The electrode 17 is electrically connected to the connecting portion 2A (see FIG. 2). Accordingly, the phase difference feeder 13 is electrically connected to the radiating element 2 via the electrode 17 and the connecting portion 2A. Similarly, the electrode 18 is electrically connected to the connecting portion 1A (see FIG. 2). Therefore, the phase difference feeder 14 is electrically connected to the radiating element 1 through the electrode 18 and the connecting portion 1A.

  The other end of the phase difference feeder 13 is electrically connected to the connecting portion 4 </ b> A by an electrode 19 formed so as to penetrate the dielectric substrate 11. Therefore, the phase difference feeder 13 is electrically connected to the radiating element 4 via the electrode 19 and the connecting portion 4A (see FIG. 2). Similarly, the other end of the phase difference feeder 14 is electrically connected to the connection portion 3 </ b> A by an electrode 20 formed so as to penetrate the dielectric substrate 11. Therefore, the phase difference feeder 14 is electrically connected to the radiating element 3 via the electrode 20 and the connecting portion 3A (see FIG. 2).

  FIG. 4 is a diagram schematically showing the antenna feeding circuit according to the first embodiment. Referring to FIG. 4, the balun 12 includes conductor patterns 12A, 12B1, 12B2, 12C1, and 12C2. Conductive patterns 12A, 12B1, 12B2, 12C1, and 12C2 are formed on main surface 11A of dielectric substrate 11. Conductive patterns 12B1 and 12B2 are connected by conductive pattern 12D. Conductive pattern 12D is formed on the main surface (main surface 11B shown in FIG. 3) of dielectric substrate 11 located on the side opposite to main surface 11A.

  In this embodiment, the balun 12 is a split balun. The split balun shown in FIG. 4 can be easily realized by using, for example, a printed circuit board manufacturing technique.

  The inner conductor 111 of the coaxial cable 110 is electrically connected to the conductor pattern 31. The conductor pattern 31 is connected to the conductor pattern 12A. The outer conductor 112 of the coaxial cable 110 is connected to the conductor pattern 32. The conductor pattern 32 is connected to the conductor pattern 12B2. Conductive pattern 12B2 is connected to conductive pattern 12B1 by conductive pattern 12D. Therefore, the conductor pattern 32 is electrically connected to the conductor pattern 12B1.

  FIG. 5 is a schematic diagram of the split balun shown in FIG. Referring to FIGS. 4 and 5, conductor patterns 12A, 12B1, 12B2, 12C1, and 12C2 are formed in a comb shape. Conductive patterns 12B1 and 12B2 are disposed outside conductive pattern 12A in proximity to conductive pattern 12A. Therefore, as shown in FIG. 4, each of conductor patterns 12B1 and 12B2 has a plurality of bent portions. The bent portion is a portion where the extending direction of the linear conductor changes by approximately 90 ° and is a portion facing the corner portion of the conductor pattern 12A. As shown in FIG. 4, the conductor pattern 12B2 is located on the opposite side of the conductor pattern 12B1 with respect to the conductor pattern 12A. One end of the conductor pattern 12B1 is connected to the conductor pattern 12A.

  FIG. 5 does not show the conductor patterns 12C1 and 12C2. However, as shown in FIG. 4, the conductor pattern 12C1 is disposed outside the conductor pattern 12B1 in proximity to the conductor pattern 12B1. The conductor pattern 12C2 is disposed outside the conductor pattern 12B2 in proximity to the conductor pattern 12B2.

  The inner conductor 111 of the coaxial cable 110 is electrically connected to the conductor pattern 12A. The outer conductor 112 of the coaxial cable 110 is electrically connected to the conductor patterns 12B1 and 12B2. One of the two phase difference feeders (for example, the phase difference feeder 14 shown in FIG. 3) is electrically connected to the conductor pattern 12A. The other of the two phase difference feeders (for example, the phase difference feeder 13 shown in FIG. 3) is electrically connected to the conductor patterns 12B1 and 12B2. The length from the terminal on the phase feeder line side to the terminal on the coaxial cable side is set to about λ / 4 (λ is the center wavelength of the used frequency band). This length may be adjusted according to the dielectric constant of the dielectric substrate 11.

  FIG. 6 is an equivalent circuit diagram of the split balun shown in FIG. As shown in FIG. 6, the split balun includes a capacitor equivalently formed between the conductor pattern 12A and the conductor pattern 12B1, and a capacitor equivalently formed between the conductor pattern 12A and the conductor pattern 12B2. And coils formed equivalently to the conductor patterns 12B1 and 12B2.

  According to the first embodiment, the balun and the phase difference feeder are formed on the same dielectric substrate by the flat conductor. Thereby, the number of parts of the antenna feeding circuit can be reduced. By reducing the number of parts of the antenna power supply circuit, an antenna power supply circuit with excellent cost can be realized.

  In the case of the conventional configuration, as shown in FIG. 23, the balun is manufactured by winding a conducting wire around the eyeglass core. For this reason, the characteristics of the balun may not be stable. Further, the balun and the phase difference feeder are configured separately. For this reason, the operation | work for connecting these two elements also generate | occur | produces. At this time, there is a possibility that the characteristics of the balun may not be stable due to the routing of the conductive wire for connecting the balun and the phase difference feeder.

  On the other hand, according to the first embodiment, since the balun formed on the dielectric substrate is used, it is possible to eliminate a factor that causes fluctuations in the characteristics of the balun such as winding a conductive wire around the core. Therefore, the characteristics of the antenna feeding circuit can be stabilized. Further, a balun and a phase difference feeder are formed on the same dielectric substrate, and these are electrically connected to each other. Therefore, the assembly work of the antenna feeding circuit can be facilitated.

  For the above reasons, according to the first embodiment, an antenna feeding circuit having excellent performance and manufacturing efficiency can be realized. Furthermore, according to the first embodiment, since an antenna feeding circuit with excellent manufacturing efficiency can be realized, the cost of the antenna feeding circuit can be reduced. Furthermore, according to the first embodiment, an antenna excellent in cost, performance, and manufacturing efficiency can be realized by configuring an antenna using such an antenna feeding circuit.

[Embodiment 2]
The antenna feeding circuit according to the second embodiment includes a capacitor between the balun and the phase difference feeding unit. In this respect, the second embodiment is different from the first embodiment.

  FIG. 7 is a schematic diagram of an antenna feeding circuit according to the second embodiment. Referring to FIG. 7, antenna feeding circuit 10A according to the second embodiment is further provided with pattern capacitors 21A and 21B formed on dielectric substrate 11, and antenna feeding circuit 10 according to the first embodiment (FIG. 2). Different from reference). The pattern capacitors 21A and 21B are provided between the balun 12 and the phase difference feeders 13 and 14.

  The pattern capacitor 21A includes an electrode 22A and an electrode 23A. Similarly, the pattern capacitor 21B includes an electrode 22B and an electrode 23B. The electrodes 22A and 22B are formed on the main surface 11A of the dielectric substrate 11. The electrodes 22 </ b> A and 22 </ b> B are electrically connected to the phase difference feed line 13 through the feed line 15 and the electrode 17. The electrodes 23 </ b> A and 23 </ b> B are formed on the main surface on the opposite side of the dielectric substrate 11. "The main surface on the opposite side of the dielectric substrate 11" corresponds to the main surface 11B shown in FIG. The electrodes 23 </ b> A and 23 </ b> B are electrically connected to the phase difference feed line 14 through the feed line 16 and the electrode 18. Accordingly, each of the pattern capacitors 21A and 21B is electrically connected between the phase difference feeders 13 and 14.

  In FIG. 7, the electrode 22 </ b> A and the electrode 23 </ b> A are shown to be relatively displaced when the dielectric substrate 11 is viewed in plan. This is to illustrate both the electrode 22A and the electrode 23A. When the dielectric substrate 11 is viewed in plan, the electrode 22A and the electrode 23A may overlap each other. The same applies to the arrangement of the electrodes 22B and 23B. Furthermore, the number of pattern capacitors is not limited to two, and may be, for example, one or three or more. Further, the shape of the electrodes 22A and 23A and the shape of the electrodes 22B and 23B are not limited to a square, and may be, for example, a circle or an arbitrary polygon.

  Since the configuration of the other part of the antenna power supply circuit 10A is the same as the configuration of the corresponding part of the antenna power supply circuit 10 shown in FIG. 2, the following description will not be repeated.

  FIG. 8 is a diagram for explaining the pattern capacitor shown in FIG. Referring to FIGS. 7 and 8, pattern capacitor 21 has the same structure as each of pattern capacitors 21A and 21B. The pattern capacitor 21 includes an electrode 22 formed on one main surface of the dielectric substrate 11 and an electrode 23 formed on the other main surface of the dielectric substrate 11. When the dielectric substrate 11 is viewed in plan, the capacitance value of the pattern capacitor 21 depends on the area of the overlapping portion between the electrode 22 and the electrode 23, the dielectric constant of the dielectric substrate 11, and the thickness t of the dielectric substrate 11. It is determined.

  The pattern capacitors 21A and 21B have a function of correcting the impedance. By providing the pattern capacitor between the balun 12 and the phase difference feeders 13 and 14, the performance of the antenna can be improved.

  Next, characteristics of the antenna having the antenna feeding circuit according to Embodiment 2 will be described. The characteristics described below are characteristics when the antenna feeding circuit according to the second embodiment is applied to a UHF antenna. The UHF antenna used for the measurement of characteristics is a so-called Yagi-type antenna. In addition to the antenna 100 shown in FIG. 1, a waveguide disposed in front of the antenna 100 (direction of arrival of radio waves), and the rear of the antenna 100 And a reflector disposed on the surface. The number of elements shown below is the total number of directors, radiators (dipole antennas), and reflectors.

  FIG. 9 is a diagram showing the frequency characteristics of the gain of the 14-element antenna having the antenna feeding circuit according to the second embodiment. The higher the gain, the better the antenna performance. Referring to FIG. 9, curve G1 shows the frequency characteristic of gain when the antenna feeding circuit according to Embodiment 2 is applied to a 14-element UHF antenna. A curve G2 represents frequency characteristics of gain when the conventional antenna feeding circuit (antenna feeding circuit shown in FIG. 23; the same applies to the following) is applied to a 14-element UHF antenna. By using the antenna feeding circuit according to the second embodiment, a gain of about 7.5 dB to about 12.5 dB was obtained in the frequency range of 470 MHz to 770 MHz. By using the antenna feeding circuit according to the second embodiment, the peak value of the gain is increased by about 0.5 dB to about 1 dB compared to the case of the conventional antenna feeding circuit. This is because the balun does not use an eyeglass core, so the loss in the wiring of the balun is reduced, and the loss is reduced by connecting the balun and the phase difference feeder with the wiring on the board. it is conceivable that.

  FIG. 10 is a diagram illustrating frequency characteristics of VSWR (voltage standing wave ratio) of a 14-element antenna having the antenna feeding circuit according to the second embodiment. The lower the VSWR, the better the antenna performance. Referring to FIG. 10, curve V1 shows the frequency characteristic of VSWR when the antenna feeding circuit according to Embodiment 2 is applied to a 14-element UHF antenna. A curve V2 shows the frequency characteristic of the VSWR when the conventional antenna feeding circuit is applied to a 14-element UHF antenna. In either case, the VSWR is at a practical level (approximately 2.0 or less).

  FIG. 11 is a diagram showing the frequency characteristics of the front / rear ratio of a 14-element antenna having the antenna feeding circuit according to the second embodiment. The front / rear ratio is a numerical value representing the ratio between the radiation intensity in front of the antenna and the intensity of the interference wave from the rear of the antenna. It can be said that the larger the front-to-back ratio value, the stronger the ability to eliminate interfering waves from the rear of the antenna, and the higher the antenna performance. Referring to FIG. 11, curve F1 shows the frequency characteristic of the front-to-back ratio when the antenna feeding circuit according to the second embodiment is applied to a 14-element UHF antenna. A curve F2 shows the frequency characteristic of the front-to-back ratio when the conventional antenna feeding circuit is applied to a 14-element UHF antenna. By using the antenna feeding circuit according to the second embodiment, the front-to-back ratio in the frequency range of 470 MHz to 770 MHz is about 18.0 dB to 22.6 dB. In addition, it can be seen that the use of the antenna feeding circuit according to Embodiment 2 increases the front-to-back ratio as compared with the conventional antenna feeding circuit.

  FIG. 12 is a diagram showing the frequency characteristics of the half width of the 14-element antenna having the antenna feeding circuit according to the second embodiment. The half-value width is an angle that is 70% lower in voltage than the gain in the main axis direction (radiation direction) of the antenna. The smaller this value, the stronger the directivity. Referring to FIG. 12, curve H1 shows the frequency characteristic of the half width when the antenna feeding circuit according to the second embodiment is applied to a 14-element UHF antenna. A curve H2 shows the frequency characteristic of the half width when the conventional antenna feeding circuit is applied to a 14-element UHF antenna. In the frequency range of 470 MHz to 770 MHz, the full width at half maximum is substantially the same, and is in the range of about 31.8 degrees to about 56.9 degrees. This shows that even if the antenna feeding circuit according to the second embodiment is used, the antenna directivity is not greatly affected.

  FIG. 13 is a diagram illustrating the frequency characteristics of the gain of the 20-element antenna having the antenna feeding circuit according to the second embodiment. Referring to FIG. 13, curve G3 shows the frequency characteristic of gain when the antenna feeding circuit according to the second embodiment is applied to a 20-element UHF antenna. A curve G4 shows the frequency characteristic of the gain when the conventional antenna feeding circuit is applied to a 20-element UHF antenna. By using the antenna feeding circuit according to the second embodiment, a gain of about 7.8 dB to about 13.5 dB was obtained in the frequency range of 470 MHz to 770 MHz. In particular, by using the antenna feeding circuit according to the second embodiment, the gain peak value is increased by about 0.5 dB compared to the conventional antenna feeding circuit.

  FIG. 14 is a diagram illustrating the frequency characteristics of the VSWR (voltage standing wave ratio) of the 20-element antenna having the antenna feeding circuit according to the second embodiment. Referring to FIG. 14, a curve V3 shows the frequency characteristic of VSWR when the antenna feeding circuit according to the second embodiment is applied to a 20-element UHF antenna. A curve V4 shows the frequency characteristic of the VSWR when the conventional antenna feeding circuit is applied to a 20-element UHF antenna. In either case, VSWR is at a practical level (a value of about 2.0 or less).

  FIG. 15 is a diagram illustrating the frequency characteristics of the front / rear ratio of the 20-element antenna having the antenna feeding circuit according to the second embodiment. Referring to FIG. 15, a curve F <b> 3 shows the frequency characteristic of the front / rear ratio when the antenna feeding circuit according to the second embodiment is applied to a 20-element UHF antenna. A curve F4 shows the frequency characteristic of the front / rear ratio when the conventional antenna feeding circuit is applied to a 20-element UHF antenna. By using the antenna feeding circuit according to the second embodiment, the front-to-back ratio is about 18.5 dB to about 22.7 dB.

  FIG. 16 is a diagram illustrating the frequency characteristics of the half width of the 20-element antenna having the antenna feeding circuit according to the second embodiment. Referring to FIG. 16, curve H3 shows the frequency characteristic of the half width when the antenna feeding circuit according to Embodiment 2 is applied to a 20-element UHF antenna. A curve H4 shows the frequency characteristic of the half width when the conventional antenna feeding circuit is applied to a 20-element UHF antenna. In the frequency range of 470 MHz to 770 MHz, the full width at half maximum is substantially the same, and is in the range of about 27.3 degrees to about 54.1 degrees.

  As described above, according to the second embodiment, the antenna feeding circuit further includes a capacitor arranged between the balun and the phase difference feeding line in addition to the configuration according to the first embodiment. Thereby, since the impedance is corrected, the performance of the antenna can be improved.

[Embodiment 3]
The antenna feeding circuit of the third embodiment is the same as that of the second embodiment in that a capacitor is disposed between the balun and the phase difference feeding unit. However, the third embodiment differs from the second embodiment in the configuration of this capacitor.

  FIG. 17 is a schematic diagram of an antenna feeding circuit according to the third embodiment. Referring to FIG. 17, antenna feed circuit 10 </ b> B according to Embodiment 3 is implemented in that it includes a pattern capacitor 27 constituted by a plurality of electrodes 25 and 26 arranged alternately between feed lines 15 and 16. This differs from the antenna feeding circuit 10A (see FIG. 7) according to the second embodiment. The plurality of electrodes 25 are connected to the feeder line 15. The plurality of electrodes 26 are connected to the feeder line 16. Therefore, the plurality of electrodes 25, 26 are formed on the same main surface (main surface 11 </ b> A) of the dielectric substrate 11. The pattern capacitor 27 is formed by a portion where the electrodes 25 and 26 face each other, a portion where the electrode 25 and the power supply line 16 face each other, and a portion where the electrode 26 and the power supply line 15 face each other.

  The plurality of electrodes 25 are electrically connected to the phase difference feed line 13 via the feed line 15 and the electrode 17. The plurality of electrodes 26 are electrically connected to the phase difference feed line 14 via the feed line 16 and the electrode 18. That is, each of the plurality of pattern capacitors 27 is electrically connected between the phase difference feeders 13 and 14. Although FIG. 17 shows a rectangle as an example of the shape of the electrodes 25 and 26, the shape of the electrodes 25 and 26 is not limited to a rectangle. For example, the electrodes 25 and 26 may have any polygonal shape. Further, the outline of the electrodes 25 and 26 may be a curve such as an arc or a sine wave.

  Since the configuration of the other part of the antenna power supply circuit 10A is the same as the configuration of the corresponding part of the antenna power supply circuit 10 shown in FIG. 2, the following description will not be repeated.

  Similar to the second embodiment, according to the third embodiment, a capacitor is provided between the balun 12 and the phase difference feeders 13 and 14. This capacitor has a function of correcting the impedance. Therefore, according to the third embodiment, the performance of the antenna can be improved as in the second embodiment.

  Note that the pattern capacitor 27 composed of the combination of the electrodes 25 and 26 is not limited to being disposed at one place. FIG. 18 is a diagram showing another example of the arrangement of pattern capacitors. As shown in FIG. 18, in the antenna power feeding circuit 10B1, a plurality of pattern capacitors 27 are divided into blocks B1 and B2. Blocks B1 and B2 are arranged separately on main surface 11A of dielectric substrate 11. That is, the plurality of pattern capacitors 27 are arranged at two places on the main surface 11 </ b> A of the dielectric substrate 11. Although two blocks are shown in FIG. 18, the number of blocks is not limited to two.

(Modification of Embodiments 2 and 3)
FIG. 19 is a diagram showing a modification of the second embodiment and the third embodiment. Referring to FIG. 19, antenna feeding circuit 10C includes chip capacitors 28 and 29 instead of pattern capacitors 21A and 21B shown in FIG. 7 or pattern capacitor 27 shown in FIG. The number of chip capacitors may be at least one and is not limited to two. The configuration of the other part of the antenna feeding circuit 10C is the configuration of the corresponding part of the antenna feeding circuit 10A shown in FIG. 7, the configuration of the corresponding part of the antenna feeding circuit 10B shown in FIG. 17, or the configuration shown in FIG. Since it is the same as the structure of the corresponding part of antenna electric power feeding circuit 10B1, subsequent description is not repeated.

  One end of the chip capacitor 28 is electrically connected to the power supply line 15. The other end of the chip capacitor 28 is electrically connected to the feeder line 16. One end of the chip capacitor 29 is electrically connected to the power supply line 15. The other end of the chip capacitor 29 is electrically connected to the feeder line 16.

  The power supply line 15 is connected to the phase difference power supply line 13 via the electrode 17. The feed line 16 is connected to the phase difference feed line 14 via the electrode 18. Therefore, each of the chip capacitors 28 and 29 is electrically connected between the phase difference feeders 13 and 14. Even with the configuration of the modified example, since the capacitor is provided between the balun 12 and the phase difference feeders 13 and 14, the impedance can be corrected. Therefore, the performance of the antenna can be improved also by the configuration shown in FIG.

  As shown in FIG. 26, in the conventional antenna feeding circuit, it is not easy to place a capacitor between the balun and the phase difference feeding line for the aerial wiring. However, in the embodiment of the present invention, since the balun and the phase difference feeder are formed on the same dielectric substrate, the chip capacitor can be easily arranged as shown in FIG.

[Embodiment 4]
FIG. 20 is a schematic diagram of an antenna feeding circuit according to the fourth embodiment. Referring to FIG. 20, antenna feeding circuit 10D according to the fourth embodiment is different from antenna feeding circuit 10 according to the first embodiment (see FIG. 4) in that DC cutting capacitor 41 is provided.

  In the example shown in FIG. 20, the conductor pattern 12A is divided into two conductor patterns 12A1 and 12A2. One end of the DC cut capacitor 41 is electrically connected to the conductor pattern 12A1, and the other end of the DC cut capacitor 41 is electrically connected to the conductor pattern 12A2.

  The conductor pattern 12A1 is connected to the inner conductor 111 of the coaxial cable 110 via the conductor pattern 31. DC cut capacitor 41 connected to conductor patterns 12A1 and 12A2 and conductor patterns 12A1 and 12A2 forms a signal path connected to internal conductor 111 of coaxial cable 110. That is, in other words, the DC cut capacitor 41 is provided in a signal path connected to the inner conductor 111 of the coaxial cable 110. Since the configuration of the other part of antenna feeding circuit 10D is the same as the configuration of the corresponding part of antenna feeding circuit 10, the following description will not be repeated.

(Modification of Embodiment 4)
FIG. 21 is a diagram illustrating a configuration example of an antenna feeding circuit in which an F seat type terminal is mounted. Referring to FIG. 21, in antenna feed circuit 10 </ b> E, F seat type terminal 51 is mounted on dielectric substrate 11. The F seat type terminal 51 has a core side terminal 52 connected to the inner conductor of the coaxial cable and a ground side terminal 53 connected to the outer conductor of the coaxial cable. The core wire side terminal 52 is electrically connected to the conductor pattern 54A by soldering, for example. The ground side terminal 53 is electrically connected to the conductor pattern 54B by soldering, for example.

  Furthermore, a pattern capacitor 55 is formed on the dielectric substrate 11 in a region between the F seat type terminal 51 and the conductor patterns 31, 32A, 32B. The pattern capacitor 55 functions as an impedance adjustment capacitor.

  Pattern capacitor 55 includes an electrode 56 formed on main surface 11A of dielectric substrate 11 and an electrode 57 formed on a main surface (corresponding to main surface 11B in FIG. 3) located on the opposite side of main surface 11A. Have. When the dielectric substrate 11 is viewed in plan, the electrodes 56 and 57 overlap each other. However, in order to show the electrodes 56 and 57 in an easy-to-understand manner, the electrodes 56 and 57 are shown shifted from each other in FIG. The electrode 56 is connected to the conductor pattern 54 </ b> B of the F seat type terminal 51. Furthermore, the electrode 56 is connected to the conductor patterns 32A and 32B.

  On the other hand, the electrode 57 is connected to the conductor pattern 54 </ b> A of the F seat type terminal 51 by an electrode (not shown) penetrating the dielectric substrate 11. Further, the electrode 57 is connected to the conductor pattern 31 by an electrode (not shown) penetrating the dielectric substrate 11.

  The conductor pattern 31 is connected to the conductor pattern 12A of the balun 12. The conductor pattern 32A is connected to the conductor pattern 12B1 of the balun 12. The conductor pattern 32B is connected to the conductor pattern 12B2 of the balun 12.

  According to the fourth embodiment, the DC component can be blocked in the signal path connected to the inner conductor 111 of the coaxial cable 110 by the DC cut capacitor.

  The arrangement of the DC cut capacitor 41 is not limited as shown in FIG. 20 or FIG. As described above, the DC cut capacitor 41 may be disposed in the signal path connected to the inner conductor 111 of the coaxial cable 110. Therefore, for example, the conductor pattern 31 may be divided into two and one end and the other end of the DC cut capacitor 41 may be electrically connected to each of the conductor patterns 31 divided into two.

[Embodiment 5]
FIG. 22 is a schematic diagram of an antenna feeding circuit according to the fifth embodiment. Referring to FIG. 22, the antenna power feeding circuit 10 </ b> F according to the fifth embodiment is similar to the antenna power feeding circuit 10 </ b> D according to the fourth embodiment in that a lightning protection circuit 35 is formed between the coaxial cable 110 and the balun 12. Different from FIG. Since the configuration of the other part of the antenna power supply circuit 10F is the same as the configuration of the corresponding part of the antenna power supply circuit 10D, the following description will not be repeated.

  FIG. 23 is an enlarged view of the lightning protection circuit 35 shown in FIG. Referring to FIG. 23, the lightning protection circuit 35 includes a protrusion 36 formed on the conductor pattern 31 and a protrusion 37 formed on the conductor pattern 32. The protrusion 36 is formed so as to protrude from the conductor pattern 31 toward the conductor pattern 32. On the other hand, the protruding portion 37 is formed so as to protrude from the conductive pattern 32 toward the conductive pattern 31. The tips of the protrusions 36 and 37 are opposed to each other. Therefore, the distance between the protrusions 36 and 37 is significantly smaller than the distance d between the other portions of the conductor patterns 31 and 32.

  According to this configuration, lightning or surge superimposed on the conductor patterns 31 and 32 via the coaxial cable 110 is discharged in the gap portion between the projecting portions 36 and 37. The lightning protection circuit 35 is a varistor or arrester realized by a conductor pattern.

  The lightning protection circuit 35 according to the fifth embodiment can be applied not only to the antenna power supply circuit 10F but also to any of the already described antenna power supply circuits 10, 10A to 10E, 10B1.

  As described above, according to the fifth embodiment, the antenna power feeding circuit 10 can be protected from lightning or surge by the lightning protection circuit 35.

  Note that the configuration for surge protection is not limited to the configuration shown in FIGS. FIG. 24 is a diagram illustrating another configuration example of the antenna feeding circuit according to Embodiment 5. In FIG. Referring to FIG. 24, antenna feeding circuit 10G is different from antenna feeding circuit 10F in that lightning protection circuit 35 and DC cut capacitor 41 are omitted. Furthermore, the antenna feeding circuit 10G is different from the antenna feeding circuit 10F in that the conductor pattern 12B1 is processed in the region 12E. The region 12E is a bent portion at a position closest to the inner conductor 111 of the coaxial cable 110 among the plurality of bent portions of the conductor pattern 12B1.

  FIG. 25 is an enlarged view of the region 12E shown in FIG. 24 and 25, the outer corner of conductor pattern 12B1 (that is, the bent portion) in region 12E is cut at approximately 45 ° with respect to the linearly extending portion of conductor pattern 12B1. As a result, the line width of the conductor pattern 12B1 in the region 12E is smaller than the minimum line width of other portions of the conductor pattern 12B1. In general, since the thickness of the conductor pattern on the dielectric substrate is considered to be substantially the same, the sectional area of the conductor pattern is reduced by reducing the line width of the conductor pattern. That is, in this embodiment, the cross-sectional area of the conductor pattern 12B1 in the region 12E is about ½ of the cross-sectional area of the other part of the conductor pattern 12B1. Therefore, the resistance of the conductor pattern 12B1 in the region 12E is larger than the resistance of other portions of the conductor pattern 12B1 (about twice).

  When a lightning surge is superimposed on the inner conductor 111 of the coaxial cable 110, the lightning surge may be transmitted from the inner conductor 111 to the conductor pattern 12 through the conductor pattern 32. In such a case, a large current flows from the side close to the inner conductor 111 of the coaxial cable 110 (side where the conductor patterns 31 and 32 are disposed) also in the conductor pattern 12B1. Of the plurality of bent portions of the conductor pattern 12B1, the resistance value of the conductor pattern 12B1 of the bent portion (region 12E) closest to the internal conductor 111 is compared to the resistance value of the other portion of the conductor pattern 12B1. high. Therefore, the conductor pattern 12B1 can be fused in the region 12E.

  The tip short-circuited quarter-wavelength transmission line constituted by a gap between the conductor pattern 12A and the conductor pattern 12B1 which is a part of the balun 12 has an internal conductor 111 in the operating frequency range in order to cut off the unbalanced current component. The transmission line impedance viewed from the nearest position is almost infinite. When the region 12E of the conductor pattern 12B1 is melted, the unbalanced current component is not sufficiently cut off, so that the characteristics of the balun 12 are deteriorated. However, disconnection of the main part of the balun 12 can be avoided by fusing the conductor pattern 12B1 as close as possible to the inner conductor 111. In addition, the transmission line impedance of the short-circuited quarter-wavelength transmission line formed at the gap between the conductor pattern 12A and the conductor pattern 12B1 when viewed from the position closest to the internal conductor 111 is the region 12E of the conductor pattern 12B1. It is almost infinite even after fusing. Therefore, it is possible to prevent a large change in the characteristics of the balun. Even after the region 12E is cut off, the transmission line constituted by the gap between the conductor pattern 12A and the conductor pattern 12B1 continues, so that the connection between the coaxial cable 110 and the phase difference feeders 13 and 14 can be secured. it can.

  The portion to be processed in which the outer corner of the conductor pattern 12B1 is cut at approximately 45 ° with respect to the linearly extending portion of the conductor pattern 12B1 is not limited to the region 12E. In addition to the region 12E, the same processing may be applied to the bent portion (indicated by the region 12F in FIG. 24) of the conductor pattern 12B1, which is next to the region 12E and close to the inner conductor 111 of the coaxial cable 110.

  Further, not only the regions 12E and 12F of the bent portion of the conductor pattern 12B1, but also a region between the region 12E and the region 12F, or a portion near the inner conductor 111 of the coaxial cable 110 in the conductor pattern 12B1 and the region 12E A region where the width of the conductor pattern is narrowed may be provided in the intermediate portion so that the cross-sectional area thereof is about ½ of the cross-sectional area of the other portion.

  Further, the above-described processing of the conductor pattern 12B1 can be applied to any of the antenna power supply circuits 10, 10A to 10E, and 10B1. In the above description, the cross-sectional area of the portion where the width of the conductor pattern is narrowed is ½ of the cross-sectional area of the other portion. However, the cross-sectional area is smaller than that of the other part, and when a predetermined lightning surge current flows, it should be blown prior to the other part. It is not necessary to limit to ½ of the cross-sectional area of this part.

  In each of the above embodiments, a split balun has been shown as an example of a balun formed by a planar conductor. However, the balun formed by the planar conductor is not limited to the split balun, and may be, for example, a U balun.

  In each of the above embodiments, the inner conductor 111 of the coaxial cable 110 is connected to the conductor pattern 12A (first conductor) of the balun 12 via the conductor pattern 31, and the outer conductor 112 of the coaxial cable 110 is connected to the conductor pattern. 32 (and conductor pattern 12D) is connected to conductor pattern 12B1 (second conductor) and conductor pattern 12B2 (third conductor) of balun 12. The arrangement of the coaxial cable 110, the arrangement of the balun 12 on the dielectric substrate 11, and the like are changed from the arrangement shown in the above embodiments and drawings (for example, FIG. 4) so that the conductor patterns 31 and 32 are made shorter. May be.

  Alternatively, the inner conductor 111 of the coaxial cable 110 may be directly connected to the conductor pattern 12A of the balun 12, and the outer conductor 112 of the coaxial cable 110 may be directly connected to the conductor patterns 12B1 and 12B2. In this case, the conductor patterns 31 and 32 can be omitted.

  Similarly, the arrangement of the coaxial cable 110, the arrangement of the balun 12 on the dielectric substrate 11 and the like so as to make the conductor patterns 15 and 16 shorter are the arrangements shown in the above embodiments and drawings (FIG. 4 and the like). You may change from For example, the pattern of the balun 12 may be a pattern that is horizontally reversed with respect to the pattern shown in FIG. In this case, the coaxial cable 110 is arranged on the left side of FIG. 4 or the like so that the inner conductor 111 of the coaxial cable 110 is directly connected to the conductor pattern 12A and the outer conductor 112 is directly connected to the conductor patterns 12B1 and 12B2. be able to. Furthermore, the length of the conductor patterns 15 and 16 can be made shorter than the pattern shown in FIG. In addition, according to such a structure, even if the conductor patterns 31 and 32 are required in order to connect the coaxial cable 110 to the balun 12, the conductor patterns 31 and 32 are made shorter than the pattern shown by FIG. be able to.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  1-4, 101-104 Radiating element, 1A-4A Connection part, 5 Feeding part, 10, 10A-10G, 10B1 Antenna feeding circuit, 11 Dielectric substrate, 11A, 11B Main surface, 12,301 balun, 12A, 12B1 , 12B2, 12C1, 12C2, 12D, 31, 32, 32A, 32B, 54A, 54B Conductor pattern, 12E, 12F region, 13, 14, 201, 202 Phase difference feed line, 15, 16 Feed line, 17-20, 22, 22A, 22B, 23, 23A, 23B, 25, 26, 56, 57 electrode, 21, 21A, 21B, 27, 55 pattern capacitor, 28, 29 chip capacitor, 35 lightning protection circuit, 36, 37 protrusion, 41 DC cut capacitor, 51 F seat type terminal, 52 core wire side terminal, 53 ground side terminal, 63, 64, 68, 69 terminal, 66, 67 insulated conductor, 100 antenna, 110 coaxial cable, 111 inner conductor, 112 outer conductor, 113 insulator, B1, B2 block.

Claims (10)

A dielectric substrate;
First and second feed lines, each formed on the dielectric substrate by a conductor, for providing phase difference feed to the two antennas;
An antenna power supply circuit comprising: a balun formed on the dielectric substrate by a conductor and electrically connected to the first and second power supply lines.   The antenna feeding circuit according to claim 1, further comprising a capacitor electrically connected between the first feeding line and the second feeding line. The dielectric substrate has a first main surface and a second main surface located opposite to the first main surface;
The capacitor is
A first electrode disposed on the first main surface;
The antenna feeding circuit according to claim 2, further comprising: a second electrode disposed on the second main surface so as to face the first electrode. The capacitor includes first and second electrodes,
The antenna feeding circuit according to claim 2, wherein the first and second electrodes are disposed to face each other on the same main surface of the dielectric substrate.   The antenna feeding circuit according to any one of claims 1 to 4, wherein the balun is a split balun.   The balun is formed on one of two main surfaces of the dielectric substrate, and the first and second feeders are formed on the other of the two main surfaces of the dielectric substrate. The antenna feeding circuit according to any one of? Further comprising third and fourth feeders for connecting the balun to the inner and outer conductors of the coaxial line;
The third and fourth feeder lines are formed on the same main surface of the dielectric substrate,
Each of the third and fourth power supply lines protrudes from one of the third and fourth power supply lines to the other, so that an interval between the third power supply line and the fourth power supply line is increased. The antenna feeding circuit according to claim 1, wherein the antenna feeding circuit has a projecting portion configured to be narrowed. The balun is
A first conductor formed in a comb shape and electrically connected to the inner conductor of the coaxial line;
A second conductor having a plurality of bent portions by being formed in a comb shape along the first conductor outside the first conductor;
A plurality of bent portions are located on the opposite side to the second conductor with respect to the first conductor and formed in a comb shape along the first conductor outside the first conductor. And a third conductor having
One end of the second conductor is connected to the first conductor;
The third conductor is connected to the second conductor;
Of the plurality of bent portions of the second conductor, the line width of the bent portion that is at least closest to the inner conductor is larger than the line width of the smallest portion of the other portion of the second conductor. The antenna feeding circuit according to claim 1, which is small.   The antenna feeding circuit according to any one of claims 1 to 7, further comprising a DC cut capacitor provided in a signal path electrically connected to the inner conductor of the coaxial line. The antenna feeding circuit according to any one of claims 1 to 9,
An antenna comprising: first and second radiating elements connected to the first and second feed lines of the antenna feed circuit, respectively.

Images