JP2010068173A - Radio reception device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio reception device which selectively receives a horizontal polarized wave and a vertical polarized wave, excludes an unnecessary signal due to circular polarization, and is applicable over a wide range. <P>SOLUTION: The radio reception device includes a first antenna 10 receiving a horizontal polarized radio wave, a second antenna 20 receiving a vertical polarized radio wave and differing in position by λ in the arrival direction of the radio wave, a rat race circuit 31 which includes first and second ports connected to the first and second antenna 10 and 20, and outputs a composite high-frequency signal from third and fourth ports, and a selector switch circuit 33 which includes first to fourth contacts connected to the first to fourth ports of the rat race circuit 31 respectively and selects and connects one of the contacts to a following stage. The first and second ports are connected by transmission lines having such a length that the impedance obtained by viewing the first and second contacts from the first and second ports is infinite, and the third and fourth ports are connected by transmission lines having such a length that the impedance obtained by viewing the third and fourth contacts from the third and fourth ports is zero. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless reception device that performs wireless communication using radio waves.

  Wireless communication using megahertz band radio waves is used in various fields. For example, an electric power company patrols the state of power distribution equipment for general consumers, and quickly repairs the power distribution equipment that has failed to supply electricity stably to the consumers. For this reason, the sales office has a car for patrol in the business area, and communication by radio waves is performed between the sales office and the car for communication and instructions. Since the sales office communicates with a moving automobile, base stations are installed in tall buildings or mountains to ensure a wide range of communications. The sales office and the car communicate with each other via a base station. For this reason, the business office and the base station are usually connected by wire, but when the base station is in a mountain or the like, it is difficult to lay the cable. The sales office and the base station are connected by a fixed line using polarization or vertical polarization.

  By the way, a 60 MHz radio wave normally penetrates the ionosphere, so that the reflected wave from the ionosphere does not affect the fixed line. However, an ionosphere with a high ionization degree called a sporadic E layer may appear due to seasonal factors. When the sporadic E layer is generated, horizontal and vertical polarizations in the 60 MHz band are reflected by the sporadic E layer. A circularly polarized wave component appears in the horizontally and vertically polarized waves reflected by the sporadic E layer. In addition, radio waves that use the same distant frequency that are not normally received may propagate abnormally and be received at a sales office or the like. In this case, when interference occurs and the signal transmitted by radio waves is voice, it may be difficult to hear the voice.

In order to cope with such a situation, there is an apparatus for sharing transmission and reception by circularly polarized waves, horizontal polarized waves, and vertically polarized waves (see, for example, Patent Document 1).
JP-A-8-237002

  By the way, the circuit described above requires various circuits. In order to share transmission and reception by circular polarization, horizontal polarization, and vertical polarization, a polarization synthesis circuit is added to the apparatus, and this circuit is composed of a hybrid synthesizer and a phase shifter. According to this apparatus, when horizontal polarization and vertical polarization are received, the polarization combining circuit converts these polarizations into circular polarization once. In other words, sharing is performed by adding a polarization synthesis circuit to a device that transmits and receives circularly polarized waves. As a result, the conventional apparatus is based on an apparatus that transmits and receives circularly polarized waves, so that the apparatuses that can be shared are limited.

  In addition, the directivity can be improved by increasing the size of the antenna, and the reflected wave from the sporadic E layer can be reduced. In this case, however, the antenna is made large, which is disadvantageous for natural conditions such as typhoons and snowfall.

  An object of the present invention is a radio that solves the above-described problems, enables selective reception of horizontally polarized waves and vertically polarized waves, eliminates unnecessary signals due to circularly polarized waves, and enables application in a wide range. To provide a receiving apparatus.

  In order to solve the above problems, the invention of claim 1 is directed to a first antenna that receives a horizontally polarized radio wave and outputs a high frequency signal, and receives a vertically polarized radio wave and outputs a high frequency signal. In addition, the second antenna, which is different from the first antenna in the direction of arrival of the radio wave by a quarter wavelength of the radio wave, and the first and second ports are respectively connected to the first and second antennas. And the third and fourth ports output the synthesized high frequency signal, and the four minutes between the first and third ports, the first and fourth ports, and the second and third ports. A rat race in which a transmission line having an electrical length of 1 wavelength is connected and a transmission path having an electrical length of 3/4 wavelength is connected between the second and fourth ports. Circuit and first to fourth contacts are connected to the first to fourth ports of the rat race circuit. And a switch circuit that selects one of the contacts and connects to the next stage, and the impedance of the first and second ports viewed from the first and second ports is infinite. In the transmission line having a length, the first and second ports are connected, and the transmission line having a length in which the impedance when the third and fourth contacts are viewed from the third and fourth ports is zero, A wireless receiving device is characterized in that the third and fourth ports are connected.

  In the first aspect of the invention, the first and second antennas are used. The second antenna is arranged so that the position of the second antenna is different from that of the first antenna with respect to the arrival direction of the radio wave by a quarter wavelength of the radio wave. In the first aspect of the invention, the following characteristics of the transmission line forming the rat race circuit are utilized. When the cable length of the transmission line is λ / 4, when one end is opened, the impedance viewed from the other end becomes zero. Conversely, when one end is short-circuited, the impedance viewed from the other end becomes infinite.

  In such a state, when the first contact is selected by the switch circuit, the impedance of the rat race circuit viewed from the first port is all infinite, and only the first antenna is connected to the first port. Will be connected. As a result, the switch circuit outputs a high-frequency signal from the first antenna. The high-frequency signal output at this time is due to the horizontally polarized wave received by the first antenna. Similarly, when the second contact is selected by the switch circuit, only the second antenna is connected to the second port of the rat race circuit. As a result, the switch circuit outputs a high-frequency signal from the second antenna. The high frequency signal output at this time is due to the vertically polarized wave received by the second antenna.

  When the third contact is selected by the switch circuit, the third port outputs the synthesized high-frequency signal when the high-frequency signals from the first and second antennas are in phase due to the characteristics of the rat race circuit. . The high-frequency signal output at this time is one of right-handed circularly polarized wave and left-handed circularly polarized wave. Similarly, when the fourth contact is selected by the switch circuit, the fourth port outputs the synthesized high frequency signal when the high frequency signals from the two antennas are in reverse phase. The high-frequency signal output at this time is due to the remaining circularly polarized wave among right-handed circularly polarized wave and left-handed circularly polarized wave.

  According to a second aspect of the present invention, in the wireless receiver according to the first aspect, the first to fourth contacts of the switch circuit are opened, the first and second ports of the rat race circuit, and the first and second ports of the switch circuit. The second contact point is connected to a transmission line having an electrical length of a half wavelength or a transmission path having an electrical length that is an integral multiple of a half wavelength, respectively. The fourth port and the third and fourth contacts of the switch circuit are a transmission line having an electrical length of a quarter wavelength or an odd length multiple of a quarter wavelength. Each is connected.

  According to a third aspect of the present invention, in the wireless receiver according to the first or second aspect, the first to fourth contacts of the switch circuit are short-circuited, and the first and second ports of the rat race circuit and the first of the switch circuit are connected. The first and second contacts are connected to each other by a transmission line having an electrical length of a quarter wavelength or an odd length multiple of a quarter wavelength, respectively. The third and fourth ports and the third and fourth contacts of the switch circuit have a transmission path with an electrical length of a half wavelength or an electrical length with an integral multiple of a half wavelength. Each is connected by a road.

  According to a fourth aspect of the present invention, in the wireless reception device according to any one of the first to third aspects, the first antenna and the second antenna are formed by arranging rod-shaped antenna elements, and the antenna element The arrangement planes are arranged so as to be orthogonal to each other.

  According to a fifth aspect of the present invention, in the wireless reception device according to any one of the first to fourth aspects, each transmission path of the rat race circuit and each transmission path connecting the rat race circuit and the switch circuit are coaxial. It is characterized by being formed of a feeder line having a structure.

  According to the first aspect of the present invention, when the first or second contact is selected by the switch circuit, the switch circuit outputs a high-frequency signal from the first or second antenna. In addition, since the first antenna receives horizontally polarized waves and the second antenna receives vertically polarized waves, it is possible to receive normally used radio waves. When the third contact is selected by the switch circuit, the third port outputs a high frequency signal when the high frequency signals from the first and second antennas are in phase. As a result, a signal obtained by synthesizing a high-frequency signal in phase with one circularly polarized wave is output. When the fourth contact is selected by the switch circuit, the fourth port outputs a high-frequency signal when the high-frequency signals from the first and second antennas are in reverse phase. As a result, a signal obtained by synthesizing the anti-phase high-frequency signals by the remaining circularly polarized waves is output. As a result, it is possible to receive normally used plane waves and circularly polarized waves generated in the sporadic E layer or the like. In other words, the invention of claim 1 makes it possible to actively receive the circularly polarized wave that has caused the interference, and conversely, to positively eliminate the circularly polarized wave causing the interference. To do.

  According to the second and third aspects of the invention, since the rat race circuit and the switch circuit are connected using two types of transmission lines, the connection structure between the rat race circuit and the switch circuit can be simplified. it can.

  According to the invention of claim 4, since the first antenna and the second antenna are formed by arranging rod-shaped antenna elements, a general antenna such as a Yagi-Uda antenna is used as the first antenna. It can be used as the first and second antennas. In addition, since the arrangement plane of the first antenna and the arrangement plane of the second antenna are arranged so as to be orthogonal, it is easy to install the first antenna and the second antenna.

  According to the invention of claim 5, since each transmission path of the rat race circuit and each transmission path connecting the rat race circuit and the switch circuit are formed by a coaxial feed line, it is simple and inexpensive. A rat race circuit and a connection structure for connecting the rat race circuit and the switch circuit can be formed.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In this embodiment, a case where a sales office uses a base station installed at a high place such as a mountain in order to communicate with a traveling vehicle will be described as an example. And the case where the signal communicated is a voice. A radio receiving apparatus according to this embodiment is shown in FIG. As shown in FIG. 2, the wireless reception device in FIG. 1 is used in a wireless communication device 1 installed in a business office. In the sales office, for example, a person in charge communicates with a patrol person of the automobile 2 by radio. At this time, the base station 3 is installed in a high building, a mountainous area M or the like in order for the sales office to ensure wide-ranging communication with the automobile 2. The wireless communication device 1 and the automobile 2 in the business office communicate with each other via the base station 3. Normally, the wireless communication apparatus 1 and the base station 3 in the sales office are connected by wire, but when it is difficult to lay the cable to the base station 1, use the horizontal polarization or vertical polarization of the 60 MHz band radio wave. The sales office and the base station are connected by the fixed line. In addition, since the vehicle 2 and the base station 3 transmit and receive signals by digital communication, they are not easily affected by noise radio waves.

  By the way, an ionosphere called a sporadic E layer 200 may appear due to seasonal factors. In this case, for example, the radio wave W1 output from the base station 3 arrives directly at the radio communication apparatus 1 at the sales office, and the radio wave W2 from a distance that is not normally received is reflected by the sporadic E layer 200. In some cases, the circularly polarized wave W3 or elliptically polarized wave arrives at the radio communication apparatus 1 at the sales office. In this case, it has been a cause of interference in the past.

  The wireless receiving device of the wireless communication device 1 that receives such radio waves includes the first antenna 10 and the second antenna 20 and a receiving unit 30 as shown in FIG.

  The first antenna 10 and the second antenna 20 are Yagi / Uda antennas in which five antenna elements 11 to 15 and 21 to 25 are arranged, but antennas having different numbers of elements can be used. When the first antenna 10 and the second antenna 20 receive radio waves from the base station 3, the first antenna 10 and the second antenna 20 send high-frequency signals to the receiving unit 30. The first antenna 10 and the second antenna 20 are fixed to the pole 100 with a distance S1 apart from each other, the second antenna 20 is on the ground surface side, and the first antenna 10 is the second antenna 20. It is arranged on the upper side.

  The first antenna 10 and the second antenna 20 are installed on the pole 100 so that the arrangement surface of the antenna elements 11 to 15 and the arrangement surface of the antenna elements 21 to 25 are orthogonal to each other. In this embodiment, the first antenna 10 is installed so that the array surface of the antenna elements 11 to 15 is parallel to the ground surface, and the array surface of the antenna elements 21 to 25 is orthogonal to the ground surface. Thus, the second antenna 20 is installed. Furthermore, the first antenna 10 and the second antenna 20 are installed on the pole 100 so that the distance S2 between the tip of the first antenna 10 and the tip of the second antenna 20 is λ / 4. . Note that λ is a wavelength of a carrier wave of a fixed line used in a fixed line between the sales office and the base station. In this embodiment, compared to the tip of the first antenna 10, the tip of the second antenna 20 protrudes forward by λ / 4, that is, in the arrival direction of the radio wave.

  As described above, by arranging the first antenna 10 and the second antenna 20, the first antenna 10 and the second antenna 20 receive horizontal polarization, vertical polarization, and circular polarization. . That is, the horizontally polarized wave in which the electric field of the radio wave is horizontal with respect to the ground surface is received by the first antenna 10 in which the array surfaces of the antenna elements 11 to 15 are parallel to the ground surface. The vertically polarized wave in which the electric field of the radio wave is perpendicular to the ground surface is received by the second antenna 20 in which the array surface of the antenna elements 21 to 25 is orthogonal to the ground surface. Further, a right-handed circularly polarized wave in which the electric field of the electric wave rotates clockwise and a left-handed circularly polarized wave in which the electric field of the electric wave rotates counterclockwise are installed such that the distance S2 between the tips is separated by λ / 4. Received by the first antenna 10 and the second antenna 20. As shown in FIG. 3, since the circularly polarized wave E is generated by combining the horizontally polarized wave E1 and the vertically polarized wave E2 having a phase difference of λ / 4, that is, a phase difference of 90 degrees, the distance S2 between the tips of each other. Can be received by the first antenna 10 and the second antenna 20 which are installed apart by λ / 4. In FIG. 3, the electric field strength Eh represents the plus direction of the horizontal polarization E1, and the electric field strength Ev represents the plus direction of the vertical polarization E2.

  In this embodiment, the second antenna 20 is located in front of the first antenna 10 in the direction of radio wave arrival. In this state, as shown in FIG. 4, the first antenna 10 receives right-handed circularly polarized wave at point A1 (small circle). At this time, the level change of the horizontal polarization E1, which is a component of right-handed circular polarization, is switched from positive to negative. Since the position difference between the first antenna 10 and the second antenna 20 is λ / 4 and the phase difference between the horizontally polarized wave E1 and the vertically polarized wave E2 is also λ / 4, the first antenna 10 When receiving a right-handed circularly polarized wave at point A1 (small circle mark), the second antenna 20 receives a right-handed circularly polarized wave at point A2 (small circle mark). At this time, the level change of the vertical polarization E2, which is a component of right-handed circular polarization, is switched from positive to negative. That is, when the first antenna 10 and the second antenna 20 according to this embodiment receive right-handed circularly polarized waves, the first antenna 10 and the second antenna 20 output high-frequency signals having the same phase.

  Further, when the incoming wave is a left-handed circularly polarized wave, it is as follows. As shown in FIG. 5, the first antenna 10 receives the left-handed circularly polarized wave at point A3 (small circle mark). At this time, the level change of the horizontally polarized wave E1, which is a component of the left-handed circularly polarized wave, is switched from minus to plus. Since the difference between the first antenna 10 and the second antenna 20 is λ / 4 and the phase difference between the horizontally polarized wave E1 and the vertically polarized wave E2 is also λ / 4, the first antenna 10 is point A3. When receiving the left-handed circularly polarized wave at (small circle mark), the second antenna 20 receives the left-handed circularly polarized wave at point A4 (small circle mark). At this time, the level change of the vertically polarized wave E2, which is a component of the left-handed circularly polarized wave, is switched from plus to minus. That is, when the first antenna 10 and the second antenna 20 according to this embodiment receive the left-handed circularly polarized wave, the first antenna 10 and the second antenna 20 output high-frequency signals having opposite phases.

  The first antenna 10 and the second antenna 20 are connected to the rat race circuit 31 through a coaxial feed line. The feed lines of the coaxial structure connecting the first antenna 10 and the second antenna 20 are arbitrary as long as they have the same length.

  When receiving the high-frequency signal from the first antenna 10 and the second antenna 20, the receiving unit 30 reproduces and outputs an audio signal from the high-frequency signal. As shown in FIG. 6, the receiving unit 30 includes a rat race circuit 31, a connection unit 32, a selection switch circuit 33, and a receiver 34.

The rat race circuit 31 of the receiving unit 30 is a circuit formed using a transmission line such as a coaxial feed line. In this embodiment, a rat race circuit 31 shown in FIG. 7 is used. The rat race circuit 31 has four ports P1 to P4. Ports P1 and P2 are input terminals, and ports P3 and P4 are output terminals. Port P1, a first antenna 10, interposed the connection portion 32 is connected to the contact point 33B ₁ of the selection switch circuit 33, port P2 includes a second antenna 20, interposed the connection portion 32 selects It is connected to the contact point 33B ₂ of the switch circuit 33. The port P3 is interposed a connecting part 32 is connected to the contact 33B ₃ of the selection switch circuit 33, the port P4 is connected to the contact 33B ₄ of the selection switch circuits 33 and connection 32 interposed to. The contacts 33B _{1 to} 33B ₄ of the selection switch circuit 33 will be described later.

  A feed line 31A having a coaxial structure with an electrical length of λ / 4 is connected between the port P1 and the port P3 of the rat race circuit 31, and an electrical current of λ / 4 is connected between the port P1 and the port P4. A feed line 31B having a coaxial structure with a length is connected. Further, a coaxial feed line 31C having an electrical length of λ / 4 is connected between the port P2 and the port P3, and an electrical length of 3λ / 4 is connected between the port P2 and the port P4. A coaxial feed line 31D is connected. Each of the coaxial feed lines 31A to 31D is a transmission path through which a high-frequency signal flows.

The rat race circuit 31 operates as follows. In FIG. 7, when the clockwise direction is the direction of arrow A and the counterclockwise direction is the direction of arrow B, the high-frequency signal input to the port P1 is
Clockwise ... λ / 4 (coaxial feed line 31A)
Counterclockwise: λ / 4 (coaxial feed line 31B), 3λ / 4 (coaxial feed line 31D), λ / 4 (coaxial feed line 31C)
The port P3 is reached through both routes. At this time, the clockwise signal is delayed by λ / 4, and the counterclockwise signal is delayed by 5λ / 4, that is, λ / 4. As a result, a high frequency signal delayed by λ / 4 is output from the port P3 due to the high frequency signal input to the port P1.

The high frequency signal input to port P2 is
Clockwise: 3λ / 4 (coaxial feed line 31D), λ / 4 (coaxial feed line 31B), λ / 4 (coaxial feed line 31A)
Counterclockwise ... λ / 4 (coaxial feed line 31C)
The port P3 is reached through both routes. At this time, the clockwise signal is delayed by 5λ / 4, that is, λ / 4, and the counterclockwise signal is delayed by λ / 4. As a result, a high frequency signal delayed by λ / 4 is output from the port P3 due to the high frequency signal input to the port P2.

  Therefore, at port P3, the high frequency signal delayed by λ / 4 generated by the input to port P1 and the high frequency signal delayed by λ / 4 generated by the input to port P2 are combined.

On the other hand, the high frequency signal input to the port P1 is
Clockwise: λ / 4 (coaxial feed line 31A), λ / 4 (coaxial feed line 31C), 3λ / 4 (coaxial feed line 31D)
Counterclockwise ... λ / 4 (coaxial feed line 31B)
The port P4 is reached via both routes. At this time, the clockwise signal is delayed by 5λ / 4, that is, λ / 4, and the counterclockwise signal is delayed by λ / 4. As a result, a high frequency signal delayed by λ / 4 is output from the port P4 due to the high frequency signal input to the port P1.

The high frequency signal input to port P2 is
Clockwise ... 3λ / 4 (coaxial feed line 31D)
Counterclockwise: λ / 4 (coaxial feed line 31C), λ / 4 (coaxial feed line 31A), λ / 4 (coaxial feed line 31B)
The port P4 is reached via both routes. At this time, the clockwise signal is delayed by 3λ / 4, and the counterclockwise signal is delayed by 3λ / 4. As a result, a high frequency signal delayed by 3λ / 4 is output from the port P4 due to the high frequency signal input to the port P2.

  Therefore, at port P4, the high frequency signal delayed by λ / 4 generated at the input to port P1 and the high frequency signal delayed by 3λ / 4 generated at the input to port P2 are combined.

  The rat race circuit 31 that operates as described above has two characteristics. First, the first characteristic will be described. This characteristic is that when a high-frequency signal having the same phase is input to the ports P1 and P2 of the rat race circuit 31, a high-frequency signal synthesized from the port P3 is output and a high-frequency signal is not output from the port P4. That is, at the port P3, the high frequency signal delayed by λ / 4 generated by the input to the port P1 and the high frequency signal delayed by λ / 4 generated by the input to the port P2 are added. As a result, a high frequency signal which is added and synthesized is output from the port P3. These characteristics are referred to as in-phase output characteristics.

  Further, at the port P4, the high frequency signal delayed by λ / 4 generated by the input to the port P1 and the high frequency signal delayed by 3λ / 4 generated by the input to the port P2 are combined. As a result, the two high-frequency signals cancel each other. That is, the high-frequency signal is not output from the port P4 with the common-mode output characteristics.

  Next, the second characteristic of the rat race circuit 31 will be described. This characteristic is that when high-frequency signals having opposite phases are input to the ports P1 and P2 of the rat race circuit 31, a high-frequency signal synthesized from the port P4 is output and no high-frequency signal is output from the port P3. . That is, at the port P4, the high frequency signal delayed by λ / 4 generated by the input to the port P1 and the high frequency signal delayed by 3λ / 4 generated by the input to the port P2 are combined. At this time, since the phase of the high frequency signal applied to the port P1 is 180 degrees different from that of the high frequency signal applied to the port P2, the phase is different by λ / 2. As a result, the high-frequency signal delayed by λ / 4 generated by the input to the port P1 from the port P4 and the high-frequency signal applied to the port P1 are delayed by 3λ / 4 and only by λ / 2. High-frequency signals with different phases are added together. As a result, the added high frequency signal is output from the port P4. These characteristics are referred to as reverse phase output characteristics.

  Further, at port P3, the high frequency signal delayed by λ / 4 generated by the input to port P1 and the high frequency signal delayed by λ / 4 generated by the input to port P2 are combined. As a result, the high-frequency signal delayed by λ / 4 generated from the input to the port P1 from the port P3 and the high-frequency signal applied to the port P1 are delayed by λ / 4 and only by λ / 2. High-frequency signals having different phases are synthesized. Thereby, the antiphase high frequency signals cancel each other out at the port P3. That is, in the reverse phase output characteristic, a high frequency signal is not output from the port P3.

The selection switch circuit 33 of the receiving unit 30 connects any of the ports P1 to P4 of the rat race circuit 31 to the receiver 34 of the next stage via the connecting unit 32. The selection switch circuit 33 includes a contact 33A that can be moved by a person who uses the wireless reception device, and contacts 33B _{1 to} 33B ₄ that are fixed and open. The contact 33A is connected to the receiver 34, and the contacts 33B _{1 to} 33B ₄ are connected to the ports P1 to P4 of the rat race circuit 31 via the connection part 32, respectively. That is, the selection switch circuit 33 connects the receiver 34 to _one of the contacts 33B ₁ to 33B ₄ in order. At this time, contacts that are not connected to the contact 33A, that is, contacts that are not connected to the receiver 34 are opened.

Such a selection switch circuit 33 is constituted by, for example, a rotary switch having four contacts corresponding to the contacts 33B _{1 to} 33B ₄ . Then, the ports P1 to P4 of the rat race circuit 31 are connected to the four contacts of the rotary switch, and the rotary shaft of the rotary switch is operated. In addition, there are various types of selection switch circuit 33 such as a circuit combining a relay.

The connection unit 32 of the reception unit 30 is provided between the rat race circuit 31 and the selection switch circuit 33. The connection part 32 is formed by connection cables 32A to 32D. The connection cables 32A and 32B have a cable length of λ / 2, and connect the ports P1 and P2 of the rat race circuit 31 to the contacts 33B ₁ and 33B ₂ of the selection switch circuit 33, respectively. The connection cables 32C and 32D have a cable length of λ / 4, and connect the ports P3 and P4 of the rat race circuit 31 to the contacts 33B ₃ and 33B ₄ of the selection switch circuit 33, respectively.

  The coaxial feed line used in such a selection switch circuit 33 has the following characteristics. When the cable length of the coaxial feed line is electrically λ / 4, when one end is open, the impedance when the coaxial feed line is viewed from the other end becomes zero. On the other hand, when one end is short-circuited, the impedance when the coaxial feeder line is viewed from the other end becomes infinite. The same applies to the feeder lines 31A to 31D of the coaxial structure of the rat race circuit 31.

Since the cable length feed line of coaxial structure is electrically lambda / 4 has such characteristics, when the contacts 33B ₁ of the selection switch circuit 33 is open, connected with an electrical cable length lambda / 2 For the cable 32A, the impedance viewed from the port P1 becomes infinite. Connection cable 32B is also similar, when the contacts 33B ₂ of the selection switch circuit 33 is opened, the connection cable 32B, impedance viewed from the port P2 is infinite. The cable lengths of the connection cables 32A and 32B are not limited to λ / 2 electrically, but may be any length as long as the impedance viewed from the ports P1 and P2 is infinite.

Meanwhile, when the contacts 33B ₃ of the selection switch circuit 33 is opened, the connection cable 32C which electrically with the cable length of lambda / 4, the impedance seen from the port P3 is zero. Connection cable 32D is similar, when the contacts 33B ₄ of the selection switch circuit 33 is opened, the connection cable 32D, the impedance viewed from the port P4 is zero. The cable lengths of the connection cables 32C and 32D are not limited to λ / 4 electrically, and may be any length as long as the impedance viewed from the ports P3 and P4 is zero.

  When the receiver 34 receives a high frequency signal from the contact 33A of the selection switch circuit 33, the receiver 34 reproduces sound from the high frequency signal. Then, the receiver 34 outputs the audio reproduction signal to a subsequent circuit, for example, an amplifier circuit.

  Next, the operation of the radio reception apparatus according to this embodiment will be described. When a person in charge at the sales office communicates with a patrol person of the automobile 2 using the wireless communication device 1, radio waves from the automobile 2 that arrive via the base station 3 are provided in the wireless communication device 1 at the sales office. The wireless receiving device receiving the signal receives it.

Office personnel operates the selection switch circuit 33 of the receiver 30 of the radio receiver, for example, to connect the contact 33A to the contact 33B _1. Thereby, the high frequency signal from the first antenna 10 is input to the receiver 34 via the connection cable 32A, the contact 33B ₁ , and the contact 33A.

When the selection switch circuit 33 connects the contact 33A to the contact 33B _1, as shown in FIG. 8, the contact _33B 2 _{~33B 4} is opened. When the contact 33B ₂ is opened, the characteristics of the feed line of the cable length is electrically lambda / 2 of the coaxial structure, as viewed from the port P2, the impedance of the cable length is electrically lambda / 2 of the connecting cable 32B infinite Become big. In FIG. 8, the direction of viewing the impedance is indicated by a thick arrow, and the impedance is indicated by Imp. Since the impedance of the connection cable 32B viewed from the port P2 is infinite, that is, open, the impedance of the feeder 31C having a coaxial structure with a cable length of λ / 4 viewed from the port P3 becomes zero. Since the impedance of the coaxial feed line 31C viewed from the port P3 is zero, that is, a short circuit, the impedance of the coaxial feed line 31A electrically viewed from the port P1 and having a cable length of λ / 4 becomes infinite. .

In the same manner, the contacts 33B ₂ is opened, the impedance of the connecting cable 32B as viewed from the port P2 is infinite, as viewed from the port P4, feed cable length of the coaxial structure of the electrically 3 [lambda] / 4 The impedance of the electric wire 31D becomes zero. Since the impedance of the coaxial feed line 31D viewed from the port P4 is zero, that is, short-circuited, the impedance of the coaxial feed line 31A having an electrical cable length of λ / 4 viewed from the port P1 becomes infinite. .

Thus, since the impedance viewed from the port P1 is infinity, i.e. it opened, in a state in which the path from the contact point 33B ₂ of the selection switch circuit 33 to the port P1 is not connected. In the same way, ready unconnected path from contact point 33B ₃ of the selection switch circuit 33 to the port P1, a state that is not connected to the path from the contact 33B ₄ of the selection switch circuit 33 to the port P1 . That is, only the first antenna 10 and the connection cable 32A are connected to the port P1. Therefore, only the high frequency signal from the first antenna 10 is input to the receiver 34. This state is for receiving the horizontally polarized wave by the first antenna 10.

Salespeople plant, by operating the selection switch circuit 33 of the receiver 30 of the wireless reception device, connecting the contacts 33A of the selection switch circuit 33 to the contact point 33B _2, equivalent to connect the contact 33A to the contact 33B ₁ as described above, a state that is not connected to the path from the contact point 33B ₁ of the selection switch circuit 33 to the port P2. Further, since the state in which the path from the contact point 33B ₃ of the selection switch circuit 33 to the port P2 is not connected, the state of the path leading to the port P2 from the contact 33B ₄ is not connected to the selection switch circuit 33. That is, only the second antenna 20 and the connection cable 32B are connected to the port P2. Therefore, only the high frequency signal from the second antenna 20 is input to the receiver 34. This state is for receiving vertically polarized waves by the second antenna 20.

Salespeople plant, by operating the selection switch circuit 33 of the receiver 30 of the wireless reception device, connecting the contacts 33A of the selection switch circuit 33 to the contact 33B _3, impedance viewed from the port P3 is zero. That is, all the paths from the contact 33B ₁ , the contact 33B ₂ , and the contact 33B ₄ to the port P3 are connected to the port P3. In this state, the common mode output characteristic of the rat race circuit 31, when the high-frequency signal and the high frequency signal from the second antenna 20 from the first antenna 10 are in phase with respect to the contact 33B ₃ of the selection switch circuits 33 Thus, the port P3 of the rat race circuit 31 sends a high frequency signal. The selection switch circuit 33 outputs this high frequency signal to the receiver 34. In other words, when the selection switch circuit 33 connects the contact 33A to the contact 33B _3, the signal acquired by combining the high-frequency signal by the received right-handed circularly polarized wave by the first antenna 10 and second antenna 20, a receiver 34 Is output. This state is for receiving right-handed circularly polarized waves.

Salespeople plant, by operating the selection switch circuit 33 of the receiver 30 of the wireless reception device, connecting the contacts 33A of the selection switch circuit 33 to the contact 33B _4, impedance viewed from the port P4 is zero. That is, all the paths from the contacts 33B _{1 to} 33B ₃ to the port P4 are connected to the port P4. In this state, the contact 33B ₄ of the selection switch circuit 33 when the high-frequency signal from the first antenna 10 and the high-frequency signal from the second antenna 20 are in reverse phase due to the reverse-phase output characteristics of the rat race circuit 31. On the other hand, the port P4 of the rat race circuit 31 sends a high frequency signal. The selection switch circuit 33 outputs this high frequency signal to the receiver 34. In other words, when the selection switch circuit 33 connects the contact 33A to the contact 33B _4, the signal acquired by combining the high-frequency signal by the received left-hand circularly polarized by the first antenna 10 and second antenna 20, outputs to the receiver 34 Is done. This state is for receiving left-handed circularly polarized waves.

  As described above, when the person in charge at the sales office operates the selection switch circuit 33 of the reception unit 30 of the wireless reception device, the selection switch circuit 33 sequentially sends four high-frequency signals to the receiver 34. The receiver 34 reproduces sound from the high-frequency signal and outputs the reproduced signal to an amplifier at the next stage. As described above, the person in charge at the sales office may operate the selection switch circuit 33 so that a reproduction signal in an optimal state, that is, an easy-to-hear sound can be obtained.

Thus, according to this embodiment,
a. Receive normal horizontal polarization b. Receive normal vertical polarization c. Eliminate unwanted signals of left-handed circular polarization due to sporadic E layer d. Reception can be performed by four types of reception methods, in which unnecessary signals of right-handed circular polarization by the sporadic E layer are eliminated, and an optimum reproduction signal can be selected and obtained. In particular, when a radio wave arriving from a distance becomes a right-handed circularly polarized wave, a right-handed elliptically polarized wave, a left-handed circularly polarized wave, or a left-handed elliptically polarized wave due to the influence of the sporadic E layer, it has conventionally caused interference. It was only. However, in this embodiment, right-hand circular polarization and left-hand circular polarization can be positively excluded.

  In addition, since this embodiment can be applied to any device that receives horizontal polarization and vertical polarization, the technique according to this embodiment can be applied to a wide range of reception devices. is there. Furthermore, the radio receiving apparatus according to this embodiment may be used for the base station 3. In this case, the selection switch circuit 33 of the radio reception apparatus installed in the base station 3 may be switched by an instruction signal from the sales office.

(Embodiment 2)
In the first embodiment, the electrical lengths of the connection cable 32A and the connection cable 32B are λ / 2. However, in this embodiment, the lengths of the connection cable 32A and the connection cable 32B are zero. That is, it connected directly to the port P1 of the rat race circuit 31 to a contact 33B ₁ of the selection switch circuit 33, connected directly to the port P2 to the contact point 33B ₂ of the selection switch circuit 33.

  According to this embodiment, the connection cable 32A and the connection cable 32B can be omitted, and the configuration of the connection portion 32 can be simplified.

(Embodiment 3)
In the first embodiment, the case where the radio reception apparatus in the sales office uses a fixed line using radio waves in the 60 MHz band is described as an example. However, in this embodiment, communication is performed at a higher frequency than this frequency band. . In this case, the rat race circuit 31 and the connection portion 32 are formed on the substrate instead of the coaxial feed line used in the rat race circuit 31 and the connection portion 32 of the wireless reception device. That is, since the wavelength λ is further shortened, the rat race circuit 31 and the connection portion 32 are formed by forming patterns with lengths of λ / 4, λ / 2, and 3λ / 4 on the substrate as transmission paths.

  Thereby, in order to install the rat race circuit 31 and the connection part 32 to the wireless receiver that performs communication at a frequency higher than the 60 MHz band, it is only necessary to attach a board (strip line type transmission line) on which these are formed. Therefore, it is not necessary to change the radio receiving device significantly, and the radio receiving device can be created at a lower cost.

(Embodiment 4)
In each of the embodiments described above, the receiver 34 is connected to one of the contacts 33B _{1 to} 33B ₄ of the selection switch circuit 33 in order. At this time, contacts that are not connected to the contact 33A, that is, contacts that are not connected to the receiver 34 are open. In contrast, in this embodiment, the contacts not connected to the receiver 34 are short-circuited, that is, grounded.

  Usually, the feed lines 31A to 31D having the coaxial structure of the rat race circuit 31 and the feed lines having the coaxial structure used as the connection cables 32A to 32D of the connection portion 32 are used with their shields grounded. Therefore, when a contact that is not connected to the receiver 34 is grounded, the contact is short-circuited.

Selection switch circuit 33 to such connection, for example, as shown in FIG. 9, is formed by using a rotary switch 33 ₁₀ with four circuit 4 contacts. That is, the circuits 33 _{11 to} 33 ₁₄ of the rotary switch 33 ₁₀ are used to connect or ground the ports P1 to P4 of the rat race circuit 31 to the receiver 34, respectively.

In this case, the lengths of the connection cables 32 </ b> A to 32 </ b> D of the connection unit 32 are reversed from those in the first embodiment. The connection cables 32A and 32B have an electrical length of λ / 4, and the connection cables 32C and 32D have an electrical length of λ / 2. By doing so, for example, when the contacts 33B ₁ of the selection switch circuit 33 are short-circuited, the connection cable 32A electrically with the cable length of lambda / 4, the impedance seen from port P1 becomes infinite. The same applies to the connection cable 32B.

  According to this embodiment, since the contacts not connected to the receiver 34 are short-circuited, the possibility that noise or the like is mixed from the outside can be reduced.

  As mentioned above, although each embodiment of this invention has been described in detail, the specific configuration is not limited to each embodiment, and even if there is a design change or the like without departing from the gist of this invention, It is included in this invention. For example, although the case where the wireless communication system according to each embodiment is used in an electric power company is taken as an example, the present invention can be used in various fields that use wireless communication using radio waves in a megahertz band or a gigahertz band.

1 is a configuration diagram illustrating a wireless reception device according to Embodiment 1. FIG. It is a figure explaining a mode that an electromagnetic wave is transmitted. It is a figure explaining the mode of composition of circular polarization. It is a figure explaining the mode of reception of right-handed circularly polarized wave. It is a figure explaining the mode of reception of left-handed circular polarization. It is a block diagram which shows the structure of a receiving part. It is a figure explaining a rat race circuit. It is a figure which shows the relationship of an impedance. FIG. 10 is a circuit diagram illustrating a selection switch circuit according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 10 1st antenna 20 2nd antenna 30 Reception part 31 Rat race circuit 32 Connection part 33 Selection switch circuit (switch circuit)
34 Receiver

Claims (5)

A first antenna that receives horizontally polarized radio waves and outputs a high-frequency signal;
A second antenna that receives vertically polarized radio waves and outputs a high-frequency signal, and is different in position from the first antenna with respect to the direction of arrival of the radio wave by a quarter wavelength of the radio waves;
The first and second ports are connected to the first and second antennas, respectively, and the third and fourth ports output the synthesized high-frequency signal, and the first and third ports, A transmission line having an electrical length of a quarter wavelength is connected between the first and fourth ports and between the second and third ports, and between the second and fourth ports, four minutes. A rat race circuit to which a three-wavelength electrical length transmission line is connected;
First to fourth contacts are connected to the first to fourth ports of the rat race circuit, respectively, and a switch circuit that selects one of the contacts and connects to the next stage;
The first and second ports are connected to the first and second ports, the first and second ports are connected, and the third and second ports are connected. The third and fourth ports are connected by a transmission line having a length of zero impedance when the third and fourth contacts are viewed from the four ports, respectively.
A wireless receiving device. The first to fourth contacts of the switch circuit are opened,
The first and second ports of the rat race circuit and the first and second contacts of the switch circuit are electrically connected to a half-wavelength electrical length or an integral multiple of a half-wavelength. Each of the third and fourth ports of the rat race circuit and the third and fourth contacts of the switch circuit are electrically connected to each other by a quarter wavelength. Each is connected by a transmission line having an electrical length that is an odd multiple of a quarter wavelength.
The wireless receiver according to claim 1, wherein The first to fourth contacts of the switch circuit are short-circuited,
The first and second ports of the rat race circuit and the first and second contacts of the switch circuit are electrically connected to a quarter-wavelength electrical length or an odd-numbered quarter-wave electrical path. Each of the third and fourth ports of the rat race circuit and the third and fourth contacts of the switch circuit are electrically connected to each other with a half-wavelength electrical length. Each is connected by a transmission line having an electrical length that is an integral multiple of a half wavelength.
The wireless receiver according to claim 1 or 2, wherein The first antenna and the second antenna are formed by arranging rod-shaped antenna elements, and are arranged so that the arrangement surfaces of the antenna elements are orthogonal to each other.
The wireless reception device according to claim 1, wherein the wireless reception device is a wireless communication device. Each transmission path of the rat race circuit and each transmission path connecting the rat race circuit and the switch circuit are formed by coaxial feeders.
The wireless reception device according to claim 1, wherein the wireless reception device is a wireless communication device.

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