JP6387984B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device used for a wireless device or the like.

  As a vertically polarized antenna device used for a radio device, a monopole antenna which is a linear antenna configured by standing a rod-shaped conductor on a ground conductor is generally used. In the case of an antenna device used for a wireless device, it is required to use in a wide frequency range, such as using different frequencies for transmission and reception. In order to widen the frequency range that can be used with the monopole antenna, the conductor diameter can be increased, or the conductor can be bent or the conductor load line added to the umbrella shape to effectively increase the conductor diameter. (For example, see Patent Document 1) and a structure in which a conductor is extended radially from the center of the antenna or surrounding the center of the antenna (for example, see Patent Document 2).

JP 63-178602 A (FIG. 1) Registered Utility Model Publication No. 3-14810 (FIGS. 1, 3 and 4)

  The conventional antenna device has a problem that when the load line is extended, if the load line is too close to the ground conductor, coupling with the ground conductor occurs, and the radiation efficiency of the antenna deteriorates. Moreover, since the ground capacity is generated for the above-described reason, the antenna bandwidth defined by the standing wave ratio VSWR (Voltage Standing Wave Ratio) is narrowed. Therefore, there is a problem that it is difficult to use in a plurality of frequency bands. In addition, it is difficult to use one antenna for a plurality of frequencies when the frequencies of the antennas are separated only by increasing the diameter of the conductor of the antenna.

  The present invention has been made to solve the above problems, and an object thereof is to obtain an antenna device that can be used at a plurality of frequencies.

The antenna device according to the present invention includes a first conductor high frequency signal is fed between the ground conductor, the first conductor and the one end before SL is connected to the ground conductor to said first conductor a second conductor rod-shaped are on opposite sides, prior Symbol third conductor and the said first conductor second for connecting the first conductor and an end portion remote from said first conductor of the second conductor A high-frequency signal having a first frequency determined by a length of a path between the first conductor, the third conductor, and the second conductor is cut off between the conductors, and the first conductor and the third conductor are connected in series. And a selective transmission section that selectively transmits a high-frequency signal having a second frequency higher than the first frequency, which is determined by the length of the path passing through the first frequency .

  In the present invention, the length of the current path of the antenna for each signal differs between the signal that passes through the selective transmission part and the signal that cannot pass through the selective transmission part, so it is used at a frequency corresponding to the length of each current path. A possible antenna device can be obtained.

It is a figure which shows the structure of the antenna apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the selective transmission part of the antenna device which concerns on Embodiment 1 of this invention. The flow of the electric current of the high frequency signal which the selective transmission part of the antenna apparatus which concerns on Embodiment 1 of this invention interrupts | blocks is shown. The flow of the electric current of the high frequency signal which the selective transmission part of the antenna apparatus which concerns on Embodiment 1 of this invention permeate | transmits is shown. It is a figure which shows the relationship between the frequency and standing wave ratio of the antenna device which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the antenna apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the circuit structure of the selective transmission part of the antenna device which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the antenna apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the antenna device which concerns on Embodiment 4 of this invention. It is a figure which shows the structure of the antenna device which concerns on Embodiment 5 of this invention.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of an antenna device according to Embodiment 1 of the present invention. In FIG. 1, the antenna device includes a ground conductor 1, a first conductor 2 to which a high-frequency signal is fed, a first conductor 2 and one end connected to the first conductor 2, opposite to the ground conductor 1. A rod-shaped second conductor 3 present on the side, a selective transmission part 4 between the first conductor 2 and the second conductor 3 for selectively transmitting a signal between the first conductor 2 and the second conductor 3; A plurality of third conductors 5 such as 5a, 5b, and 5c are provided to connect the end of the second conductor 3 on the side far from the first conductor 2 and the first conductor.

  The ground conductor 1 serves as a reference for the potential of the antenna device, and is composed of a conductor or the like on the ground or underground where the antenna device is installed. In FIG. 1, the ground conductor 1 is represented by a circle, but is not limited to a circle, and an appropriately designed shape can be selected. In addition, when installed outdoors, the ground surface may be the ground conductor 1. The first conductor 2 is insulated from the ground conductor 1, and a high-frequency signal is fed by a transmission line 6 such as a coaxial cable through a power feeding unit 7 connected to the ground conductor 1 and the first conductor 2. In FIG. 1, the ground conductor 1 that appears to be cut off near the transmission line 6 represents that the ground conductor 1 and the transmission line 6 are electrically separated from each other. The ground conductor 1 is not cut.

  The first conductor 2 and the second conductor 3 are either self-supporting due to the rigidity of the conductor itself or the ends of the first conductor 2 and the second conductor 3 are pulled and supported by branch lines 9a, 9b, 9c and the like. The selective transmission unit 4 transmits a high-frequency signal having a frequency higher than the predetermined frequency f0 by a π-type high-pass filter circuit, and blocks a high-frequency signal having a frequency lower than the frequency f0. The ground of the high-pass filter circuit is grounded to the ground conductor 1 by the ground line 8.

  The third conductors 5a, 5b, and 5c are arranged so as not to be electrically connected to each other except for both ends. In order to make the electrical characteristics of the antenna device have good symmetry, it is desirable that the third conductors 5a, 5b, and 5c be arranged so as to be 120 ° rotationally symmetric with the second conductor 3 as the central axis. In FIG. 1, the number of the third conductors 5 is illustrated as 3, but the number of the third conductors 5 is not limited to 3, and may be 1, 2 or 4 or more. When the number of the third conductors 5 is N (N ≧ 2), these are arranged with rotational symmetry of (360 / N) °.

  FIG. 2 is a diagram showing a circuit configuration of the selective transmission unit 4 of the antenna device according to Embodiment 1 of the present invention. Terminals 101 and 102 are input / output terminals of the selective transmission unit 4, and are connected to the first conductor 2 and the second conductor 3, respectively. The capacitor 103a is inserted in series between the first conductor 2 and the second conductor 3, and inductors 104a and 104b grounded to the ground conductor 1 through the ground 105 are connected to both ends of the capacitor 103a. Yes. Capacitor 103a and inductors 104a and 104b constitute a π-type high-pass filter that transmits a high-frequency signal having a frequency higher than a predetermined frequency f0 and blocks a high-frequency signal having a frequency lower than frequency f0.

  Similarly, capacitors 103b and 103c are respectively inserted in series between the first conductor 2 and the second conductor 3, and inductors grounded to the ground conductor 1 via the ground 105 are connected to both ends of each capacitor. 104b, 104c, 104d and the like are connected to form a multi-stage π-type high-pass filter. The inductors 104a, 104b, 104c, and 104d can be freely selected as long as a predetermined inductance value can be obtained, such as a chip inductor or a coil. Capacitors 103a, 103b, and 103c can be freely selected as long as a predetermined capacitance such as a chip capacitor or a parallel plate conductor can be obtained.

  3 and 4 are diagrams schematically showing the electrical operation of the antenna device configured as shown in FIG. FIG. 3 shows the current flow of the high-frequency signal blocked by the selective transmission part, and FIG. 4 shows the current flow of the high-frequency signal transmitted by the selective transmission part.

  3 and 4, the point where the third conductors 5a, 5b and 5c are connected to the first conductor 2 is a point A, and the point where the third conductors 5a, 5b and 5c are connected to the second conductor 3 is a point. Let B be a point where the selective transmission part 4 and the first conductor 2 are connected. 3 and 4, currents 201a, 201b, and 201c are currents that flow on the third conductors 5a, 5b, and 5c. A current 202 is a current flowing on the second conductor 3. 3 and 4, the directions of the currents 201 a, 201 b, 201 c and the direction of the current 202 are alternately switched according to the period corresponding to the frequency of the high-frequency signal output from the transmission line 6 to the power feeding unit 7.

  In the antenna device shown in FIG. 1, when the first frequency f1 is a frequency lower than the frequency f0, the selective transmission unit 4 is a filter that blocks a high-frequency signal having a frequency lower than the frequency f0. Is interrupted by the filter 3. Therefore, as shown in FIG. 3, at the first frequency f1, the currents 201a, 201b, and 201c reach the point B from the point A through the third conductors 5a, 5b, and 5c, respectively. Since the third conductors 5a, 5b, and 5c have the same length, the current of the high-frequency signal that reaches the point B via each of the third conductors 5a, 5b, and 5c is synthesized in phase and flows to the second conductor 3 , Point C is reached. Therefore, in the antenna device shown in FIG. 1, a monopole antenna having a bent shape is constituted by the first conductor 2, the third conductor 5, and the second conductor 3 at the first frequency f1.

  Further, in the antenna device shown in FIG. 1, when the second frequency f2 is a frequency higher than the frequency f0, the selective transmission unit 4 is a filter that transmits a high-frequency signal having a frequency higher than the frequency f0. The current of the high frequency signal is transmitted by the filter 3. Therefore, as shown in FIG. 4, at the second frequency f2, the currents 201a, 201b, and 201c reach the point B from the point A through the third conductors 5a, 5b, and 5c, and the current 202 is The point B is reached from the point C through the second conductor 3. Since the third conductors 5a, 5b, and 5c have the same length, the current of the high-frequency signal that reaches the point B via each of the third conductors 5a, 5b, and 5c is combined in phase and flows to the second conductor 3. . Since the third conductors 5a, 5b, and 5c have the same length, the current of the high-frequency signal that reaches the point B via each of the second conductors 5a, 5b, and 5c is also synthesized in phase. Therefore, in the antenna device, a monopole antenna having different electrical lengths is configured by the first conductor 2 and the second conductor 3 and the first conductor 2 and the third conductor 5 at the second frequency f2.

  Here, at the first frequency f1, the current path is A → B → C, and is longer than A → C or A → B, which is the current path at the second frequency f2. That is, by appropriately selecting the length of the second conductor 5 (5a, 5b, 5c), the current of the first frequency f1 resonates in the current path A → B → C, and the current path A → C or The optimal electrical length of the antenna can be designed for each of the first frequency f1 and the second frequency f2 so that the current of the second frequency f2 resonates from A to B, and the radiation efficiency of the antenna can be increased. is there. That is, in this antenna device, the first frequency f1 is determined by the length of the path that passes through the first conductor, the third conductor, and the second conductor in series. The second frequency f2 is determined by the length of a path that passes through the first conductor and the third conductor in series or a path that passes through the first conductor and the second conductor in series.

  FIG. 5 is a graph showing the relationship between the frequency and the standing wave ratio (VSWR characteristics) of the antenna device according to Embodiment 1 of the present invention. In FIG. 5, it can be seen that the VSWR is reduced in the two frequency bands of the first frequency f1 and the second frequency f2, and matching with the feeder line is facilitated. Further, as described above, since current paths having different electrical lengths are formed at the second frequency f2, the frequency range in which the VSWR decreases near the second frequency f2 is wide.

  As described above, in the antenna device according to the first embodiment, the selective transmission unit 4 blocks the current of the high-frequency signal having the first frequency f1 and transmits the current of the high-frequency signal having the second frequency f2. Current paths having different electrical lengths are formed between the high-frequency signal having the frequency f1 and the high-frequency signal having the second frequency f2. For this reason, the electrical length of the path | route which passes along the 1st conductor 2, the 3rd conductor 5, and the 2nd conductor 3 which determines the 1st frequency f1 in series, and the 1st conductor 2 and the 2nd conductor 4 which determine the 2nd frequency f2 Alternatively, by adjusting the electrical length of the current path that passes through the first conductor 2 and the third conductor 5 in series, an antenna device that can be used at two frequencies, the first frequency f1 and the second frequency f2, can be obtained. .

Embodiment 2. FIG.
FIG. 6 is a diagram showing the configuration of the antenna device according to Embodiment 1 of the present invention. In the antenna device according to the second embodiment, instead of the selective transmission unit 4 that is grounded to the ground conductor 1 by the ground wire 8, the selective transmission unit 4a that is not grounded to the ground conductor 1 and that is configured by an LC parallel resonance circuit is provided. I have.

  FIG. 7 is a diagram showing a circuit configuration of the selective transmission unit 4a of the antenna device according to Embodiment 2 of the present invention. In the antenna device according to the antenna device according to the second embodiment, the selective transmission unit 4a is a band stop filter that blocks the current of the high-frequency signal having the first frequency f1. The terminal 101 and the terminal 102 are input / output terminals of the selective transmission unit 4 a and are connected to the first conductor 2 and the second conductor 3, respectively. The capacitor 106a is inserted in series between the first conductor 2 and the second conductor 3, and one end of the inductor 107a is connected to one end of the capacitor 106a, and the other end of the inductor 107a is connected to the other end of the capacitor 106a. ing.

  The capacitor 106a and the inductor 107a constitute a resonance circuit, and the capacitance of the capacitor 106a and the inductance of the inductor 107a are adjusted so that the resonance frequency matches the first frequency f1. Similarly, capacitors 106b and 106c are inserted in series between the first conductor 2 and the second conductor 3, respectively, and inductors 107b and 107c are connected to the input and output at both ends of the capacitors 106b and 106c, respectively. A parallel resonant circuit connected in multiple stages is configured. By connecting LC parallel resonant circuits in multiple stages, the frequency characteristics of the resonant circuit are sharpened, and the current of the first frequency f1 is cut off.

  For this reason, also in the selective transmission part 4a, the current of the high frequency signal of the first frequency f1 is cut off and the current of the high frequency signal of the second frequency f2 is transmitted. As a result, also in the antenna device shown in FIG. 6, at the first frequency f1, the current of the high-frequency signal flowing through the antenna device is such that the first conductor 2, the third conductor 5, and the second conductor 3 are connected in series as shown in FIG. The first conductor 2, the third conductor 5, and the second conductor 3 constitute a monopole antenna having a bent shape. Further, at the second frequency f2, the current of the high-frequency signal flowing through the antenna device passes through the first conductor 2 and the second conductor 3 in series as shown in FIG. 4, or the first conductor 2 and the third conductor 5 are connected in series. Therefore, the first conductor and the second conductor 3, and the first conductor 2 and the third conductor 5 constitute a monopole antenna having different electrical lengths. The electrical length of the current path passing in series through the first conductor 2, the third conductor 5, and the second conductor 3 that determines the first frequency f1, and the first conductor 2 and the second conductor 4 or the second conductor that determines the second frequency f2. Similarly to the antenna device according to the first embodiment, the antenna device according to the second embodiment also adjusts the electrical length of the current path passing through the first conductor 2 and the third conductor 5 in series. An antenna device that can be used at two frequencies, frequency f1 and second frequency f2, can be obtained.

  In the selective transmission device 4a shown in FIG. 7, in order to obtain a good cutoff performance at the first frequency f1, the number of LC parallel resonant circuits connected in multiple stages is increased, and the frequency characteristics of the resonant circuit are increased. Must be sharp. For this reason, the selective transmission device 4a requires a large circuit scale. On the other hand, the selective transmission unit 4 of the antenna apparatus having the configuration shown in FIG. 1 can obtain good frequency characteristics by a small filter circuit. On the other hand, in the selective transmission part 4, since the ground wire 8 extending between the ground conductor 1 and the first conductor 2 is disposed, the selective transmission part 4 is particularly installed at a high position of the antenna device. In this case, the ground wire 8 affects the electrical characteristics of the antenna device. For this reason, which of the selective transmission unit 4 and the selective transmission unit 4a is selected is determined according to the electrical characteristics required for the antenna device, the scale of the antenna device, and the arrangement inside the antenna device.

Embodiment 3 FIG.
FIG. 8 is a diagram showing a configuration of an antenna apparatus according to Embodiment 3 of the present invention. The antenna device according to Embodiment 3 has a connection state in which a signal is transmitted between the first conductor 2 and the second conductor 3 and a blocking state in which the signal is blocked, instead of the selective transmission unit 4 or the selective transmission unit 4a. A selective transmission unit 4b, which is a switching device that performs switching, is provided.

  In the antenna device according to Embodiment 3, when the selective transmission section 4b blocks the signal between the first conductor 2 and the second conductor 3, the current flowing through the antenna device is as shown in FIG. The third conductor 5 and the second conductor 3 constitute a monopole antenna having a bent shape corresponding to the first frequency f1. When the selective transmission part 4b transmits a signal between the first conductor 2 and the second conductor 3, the current flowing through the antenna device is as shown in FIG. 4, and the first conductor, the second conductor 3, and the first conductor A monopole antenna corresponding to the second frequency f <b> 2 having different electrical lengths is formed by the second conductor 3 and the third conductor 5. For this reason, the selective transmission unit 4a performs switching so as to be in a cut-off state when the antenna device is used at the first frequency f1, and in a connected state when the antenna device is used at the second frequency f2. With this configuration, the electrical length of the current path passing in series through the first conductor 2, the third conductor 5, and the second conductor 3 that determines the first frequency f1, and the first conductor 2 and the second that determine the second frequency f2. An antenna that can be used while switching between the two frequencies of the first frequency f1 and the second frequency f2 by adjusting the electrical length of the current path passing through the conductor 4 or the first conductor 2 and the third conductor 5 in series. A device can be obtained.

Embodiment 4 FIG.
FIG. 9 is a diagram showing a configuration of an antenna apparatus according to Embodiment 4 of the present invention. Since the antenna length is several meters at a frequency with a relatively long wavelength such as a short wave band, a support structure for supporting the conductor may be required. The antenna device shown in FIG. 9 is fixed to the ground wire 10 which is a ground conductor installed on an antenna ground surface such as the ground surface 11 and is insulated from the ground wire 10 and fed with a high-frequency signal based on the ground wire 10. The first conductor 2, the rod-shaped second conductor 3 that is fixed to the first conductor 2 by an insulating block 12 that is an insulator, and exists on the opposite side of the ground wire 10, and the first conductor 2 and the second conductor 3 and a selective transmission part 4c for selectively transmitting signals, one end of which is fixed to the end of the second conductor 3 far from the first conductor 2, and the second conductor 3 is rotationally symmetrical to each other A plurality of insulating branch lines 9 (9a, 9b, 9c) that are pulled and supported in the direction to be supported, and one end part connected to the end part of the second conductor 3 far from the first conductor. Upper conductor 13 (13a, 13b, 13c), and one end of the upper conductor 1 A third conductor 5 having a lower conductor 14 (14a, 14b, 14c) connected to the end opposite to the end connected to the second conductor 3 and having the other end connected to the first conductor. (5a, 5b, 5c).

  The insulating block 12 is inserted between the first conductor 2 and the second conductor 3 in order to insulate the first conductor 2 and the second conductor 3 and fix one end of the second conductor 3 to the first conductor 2. It is an insulator. The selective transmission part 4 c is disposed in the vicinity of the insulating block 12 and is connected to the first conductor 2 and the second conductor 3, respectively. The selective transmission portion 4c may be integrated with the insulating block 12 as in the first embodiment, or may be provided separately from the insulating block 12 as shown in FIG. good. The selective transmission unit 4c has a circuit configuration similar to that of any of the selective transmission units 4, 4a, and 4b, and blocks the current of the high-frequency signal having the first frequency f1 and transmits the current of the high-frequency signal having the second frequency f2. . In other words, the selective transmission part 4c is only required to be between the first conductor and the second conductor, cut off the current of the high-frequency signal having the first frequency f1, and transmit the current of the high-frequency signal having the second frequency f2.

  Also in the antenna device shown in FIG. 9, the selective transmission unit 4c blocks the current of the high-frequency signal having the first frequency f1 and transmits the current of the high-frequency signal having the second frequency f2, so that the first frequency f1 and the second frequency are transmitted. Current paths having different electrical lengths are formed with f2. For this reason, an antenna device that can be used at two frequencies, the first frequency f1 and the second frequency f2, can be obtained in exactly the same manner as in the first to third embodiments.

  The branch line 9 (9a, 9b, 9c) supports the end of the second conductor 3 on the side far from the first conductor 2 from the viewpoint of wind resistance and earthquake resistance of the antenna element. The end of the second conductor 3 far from the first conductor 2 is supported by a branch line support 15 (15a, 15b, 15c) installed on the ground surface 11. In FIG. 9, the three branch lines 9a, 9b, and 9c are arranged so as to be 120 ° rotationally symmetric with the second conductor 3 as the central axis. Although the number of branch lines 9 is not limited to three, providing a large number of branch lines may increase the area required for installation, increase the cost of members, and increase the cost of installation and maintenance. The minimum number is desirable and 3 is desirable. The branch line 9 (9a, 9b, 9c) uses a member made of an insulator such as a resin so as not to affect the electrical characteristics of the antenna. In addition, if it is short length seeing from the wavelength of the frequency to be used, you may use a metal anchor etc. for the branch line support tool 15 which supports the branch line 9 (9a, 9b, 9c).

  The third conductor 5 (5a, 5b, 5c) is supported by the branch line 9 (9a, 9b, 9c) with the upper conductor 13 (13a, 13b, 13c) as a part thereof. Therefore, the second conductor 3 and the third conductor 5 (5a, 5b, 5c) can be supported by the branch lines 9 (9a, 9b, 9c), and the antenna device can be efficiently supported by a small number of support members. Can do. Further, the length of the third conductor 5 (5a, 5b, 5c) is adjusted by adjusting the length of the upper conductor 13 (13a, 13b, 13c) supported by the branch line 9 (9a, 9b, 9c). can do. For this reason, the first conductor 2, the third conductor 5, and the second conductor 3 that determine the first frequency f1, the electrical length passing in series, and the first conductor 2 and the third conductor that determine the high-frequency signal of the second frequency f2 are determined. The electrical length passing through the conductor 5 in series or the electrical length passing through the first conductor 2 and the second conductor 3 in series can be adjusted in a wide range.

  The electrical length of the upper conductor 13 (for example, 13a) of the third conductor 5 (for example, 5a) and the lower conductor 14 (for example, 14a) that connects the first conductor 2 can also be adjusted. By passing through a relay support 16 (for example, 16b) provided on a branch line 9 (for example, 9b) different from the branch line 9 (for example, 9a) on which the upper conductor to be connected is supported, the third conductor 5 ( For example, the length of 5a) can be increased. If the third conductor 5 (5a, 5b, 5c) is configured in this way, the length of the third conductor 5 (5a, 5b, 5c) can be made longer than that of the second conductor 3, so the frequency used is the same. Even if it exists, the height of an antenna can be made low.

Embodiment 5. FIG.
FIG. 10 is a diagram showing a configuration of an antenna apparatus according to Embodiment 5 of the present invention. In the fifth embodiment, instead of supporting the second conductor 3 with the branch line 9 (9a, 9b, 9c), the upper conductor 13 (13a, 13b) which is a part of the third conductor 5 (5a, 5b, 5c). 13c) is stretched between the end of the second conductor 3 on the side far from the first conductor and the insulating conductor support 17 (17a, 17b, 17c) installed on the ground, and the second conductor 3 is attached to the branch line 9 (9a, 9b, 9c) are pulled and supported in directions symmetrical to each other.

  In FIG. 10, one end of the upper conductor 13 (13a, 13b, 13c), which is a part of the third conductor 5 (5a, 5b, 5c), is on the side farther from the first conductor 2 of the second conductor 3. The other end of the upper conductor 13 (13a, 13b, 13c) is supported by an insulating conductor support 17 (17a, 17b, 17c) installed on the ground. One end of the lower conductor 14 (14a, 14b, 14c), which is a part of the third conductor 5 (5a, 5b, 5c), is a conductor support 17 of the upper conductor 13 (13a, 13b, 13c). The other end is connected to the first conductor 2. The other end is connected to the end supported by (17 a, 17 b, 17 c).

  In the antenna apparatus shown in FIG. 10, the conductor support 17 (17 a, 17 b, 17 c) is moved closer to or away from the first conductor 2 or the second conductor 3, so that the upper conductor 13 (13 a, 13 b, 13c) and the length of the lower conductor 14 (14a, 14b, 14c) can be adjusted. Further, the lower conductor 14 (for example, 14a) is further passed through a conductor support 17 (for example, 17b) different from the conductor support 17 (for example, 17a) on which the upper conductor 13 to be connected (for example, 13a) is supported. As a result, the length of the third conductor 5 (for example, 5a) can be further increased.

  In the fourth embodiment, an insulator such as a resin is used for the branch line 9 (9a, 9b, 9c) for indicating the second conductor 3 so as not to adversely affect the electrical characteristics of the antenna device. In general, resin branch lines are more expensive than metal branch lines. Therefore, as in the fifth embodiment, the branch conductor 9 (9a, 9b, 9c) is not used, and the third conductor 5 (5a, 5b, 5c) has the upper conductor 13 (13a, 13b, 13c). If the two conductors 3 are supported, the manufacturing cost can be reduced in addition to the effects of the configuration of the fourth embodiment.

DESCRIPTION OF SYMBOLS 1 Ground conductor, 1st conductor, 3rd conductor, 4 Selective transmission part, 5, 5a, 5b, 5c 3rd conductor, 6 Transmission line, 7 Feeding part, 8 Ground line, 9, 9a, 9b, 9c Branch line DESCRIPTION OF SYMBOLS 10 Ground wire, 11 Ground surface, 12 Insulation block, 13, 13a, 13b, 13c Upper conductor, 14, 14a, 14b, 14c Lower conductor, 15, 15a, 15b, 15c Branch line support, 16, 16a, 16b, 16c Relay support, 17, 17a, 17b, 17c Conductor support, 101, 102 Input / output terminal, 103a, 103b, 103c, 106a, 106b, 106c Capacitor, 104a, 104b, 104c, 107a, 107b, 107c Inductor, 105 Ground, 201a, 201b, 201c, 202 Current

Claims (8)

A first conductor, the ends of the first conductor and the one previous SL is connected to the high-frequency signal is fed between the ground conductor, a rod-like present on the opposite side of said ground conductor to said first conductor and second conductors, and a third conductor connecting the first conductor prior Symbol second conductor and the far side end and the first conductor, be between the said first conductor second conductor, said first A high frequency signal having a first frequency determined by a length of a path passing through the conductor, the third conductor, and the second conductor is cut off, and determined by a length of the path passing through the first conductor and the third conductor in series. A selective transmission part for selectively transmitting a high-frequency signal having a second frequency higher than the first frequency, and the electrical length of the first conductor and the second conductor at the second frequency, and the first conductor. And an antenna device having an electrical length different from that of the third conductor . The antenna device according to claim 1, wherein the third conductor includes a plurality of conductors and is disposed around the second conductor . The antenna device according to claim 2 , wherein the third conductor is arranged such that the plurality of conductors are insulated from each other except for both ends . 3. The third conductor is arranged so that the number of the plurality of conductors is N (N ≧ 2) and is rotationally symmetrical by (360 / N) ° about the rod-shaped second conductor. 4. The antenna device according to 3. The end portion on the side far from the first conductor is supported by an insulating branch line, and the third conductor is partially supported by the branch line . The antenna device according to item 1 . The antenna device according to any one of claims 1 to 4, wherein the third conductor is supported by an insulating conductor support installed on the ground . It is fixed by being insulated from the ground conductor, the first conductor to which a high-frequency signal is powered between said ground conductor, one end by a front Symbol insulator on the first conductor is fixed relative to said first conductor a second conductor rod-like present on the opposite side of the ground conductor Te is fixed from the first conductor end of the hand is the second conductor end portion on the side far, rotational symmetry of the second conductor with each other become to pull fixed direction and a plurality of branch lines of insulating, prior SL connected upper conductor end of one is supported on the branch line to the end remote from the first conductor of the second conductor, and wherein A third conductor having a lower conductor connected to the other end of the upper conductor and the first conductor; and between the first conductor and the second conductor, wherein the first conductor, the third conductor, and the first conductor Cutting off a high frequency signal of a first frequency determined by the length of a path passing through two conductors in series; Determined by the length of the path through said one conductor third conductors in series, antenna unit comprising a selectively permeable portion that selectively transmits a high frequency signal of the higher second frequency than the first frequency. Is fixed by being insulated from the ground conductor, a first conductor high frequency signal is fed, the one end by the pre-Symbol insulator on the first conductor is fixed between said ground conductor, with respect to the first conductor a second conductor rod-like present on the opposite side of the ground conductor, are connected from said first conductor end of the hand is the second conductor on the end farther, supporting the other end of the insulating And a third conductor having a lower conductor connected to the other end of the upper conductor and the first conductor. The upper conductor is a conductor that is supported by a tool and pulls and supports the second conductor in a rotationally symmetric direction. And blocking a high-frequency signal having a first frequency that is between the first conductor and the second conductor and is determined by a length of a path that passes through the first conductor, the third conductor, and the second conductor in series, Determined by the length of the path through the first conductor and the third conductor in series. Antenna unit comprising a selectively permeable portion that selectively transmits a high frequency signal higher than the first frequency second frequency.

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