JP2000068730A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a phased array antenna for multi-beam and apply the antenna to a tracking system using the multi-beam, direction finding, direction diversity. SOLUTION: This device is provided with a frequency discriminating circuit 3 to distribute signals of different frequencies received by each element antenna 1 constituting an array antenna, and plural phase shifters 4a, 4b connected with the circuit 3 and to independently give phase shifting to the respective signals of the different frequencies outputted from the circuit 3. Then, the plural signals of the different frequencies are received from each element antenna 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device used for satellite communication including a moving object corresponding to an orbiting satellite, radio control, wireless LAN, and the like.

[0002]

2. Description of the Related Art As an antenna device used in conventional mobile satellite communication, there is an antenna device having a phased array antenna composed of a plurality of element antennas. FIG.
FIG. 1A shows a configuration of a planar phased array antenna composed of four microstrip array plates 21 to 24 used in an antenna device disclosed in, for example, Japanese Patent Application Laid-Open No. 3-96105, and FIG. Is a side view, (b)
The figure shows a front view. That is, the microstrip array plates 21 to 24 including a plurality of element antennas 1 are arranged on the roof of a house in front, rear, left, and right, respectively, with a slight inclination.
By selecting and operating the plurality of microstrip array plates 21 to 24, a uniform antenna gain over a wide range is ensured. FIG. 11 is a diagram showing a configuration of a distribution / synthesis circuit connected to each of the microstrip array plates 21 to 24, which are connected to the front, rear, left and right microstrip array plates 21 to 24, respectively. Before, after, left and right distribution coupling circuits 31 to 34
And a selection circuit 40 for switching the microstrip array plates 21 to 24 to be used. The element antennas 1 of the microstrip array plates 21 to 24 are respectively connected to the phase shifters 3 of the distribution coupling circuits 31 to 32.
The outputs of the phase shifters 31a to 34a are combined by distribution couplers 31b to 34b.

[0003]

As described above, in the conventional antenna device, since one phase shifter is connected to each element antenna 1, a signal from one direction, that is, a signal from one direction, that is, Only one beam could be handled, and multi-beam could not be realized. Also, considering future orbiting satellites, it is necessary to capture and communicate with satellites using multiple beams, but at present, multi-beam antennas with phased array antennas are used. There was no. Furthermore, when multi-beams become possible with a phased array antenna,
A beam scan function, a monopulse function, a diversity function, and the like can be performed independently of a communication signal. However, as described above, in an antenna device having a conventional phased array antenna, one phase shifter is provided for each element antenna. However, there is a problem that multi-beam conversion cannot be realized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and realizes a multi-beam phased array antenna, and uses a multi-beam tracking method, direction finding, and direction diversity. It is an object of the present invention to provide an antenna device capable of performing the following.

[0005]

According to a first aspect of the present invention, there is provided an antenna apparatus comprising: a frequency discriminating circuit for distributing signals having different frequencies received by respective element antennas constituting an array type antenna; A plurality of phase shifters for independently giving a phase shift to each of the signals having different frequencies output from the circuit, so that a plurality of signals having different frequencies can be received from each element antenna. It is.

According to a second aspect of the present invention, there is provided an antenna apparatus comprising: a plurality of phase shifters for independently imparting a phase shift to a plurality of transmission signals having different frequencies transmitted from an element antenna; And a synthesizing circuit for synthesizing the outputs of the devices, so that a plurality of transmission signals having different frequencies can be transmitted from each element antenna.

An antenna device according to a third aspect of the present invention includes a power divider for distributing signals having different powers received by an element antenna, instead of the frequency discriminating circuit, and receiving a plurality of signals having different incident powers. It is made possible.

In the antenna device according to a fourth aspect of the present invention, a signal of an RF frequency is transmitted to a first stage of a frequency discriminating circuit at a first stage.
A frequency converter for converting the frequency to a signal of the F frequency is provided,
The frequency discrimination is performed in the first IF frequency band.

In the antenna apparatus according to a fifth aspect of the present invention, a frequency converter for directly converting the frequency of an RF frequency signal into I and Q channel signals, which are baseband signals, is provided before the frequency discriminating circuit. In the baseband signal band.

[0010] In the antenna device according to the sixth aspect of the present invention, the relation between the direction of the arriving signal and the frequency is fasin θa = fb
For an incoming signal having a plurality of different frequencies that satisfy sinθb, one phase shifter is used, and each incoming signal is phase-shifted by the phase shifter and then distributed to signals of a plurality of frequencies. It is something to do.

An antenna apparatus according to a seventh aspect of the present invention receives a plurality of signals according to any one of the first to third aspects with respect to an element antenna in a specific column and a specific row. And a phase shifter is provided to provide a phase for performing beam scanning on an incoming signal that is not always received.

The antenna device according to claim 8 of the present invention is applicable to a plurality of element antennas provided at positions symmetrical with respect to the center point of the array antenna. A plurality of signals described in (1) and (2) can be received, and the outputs of the respective element antennas are combined in phase and in opposite phases to obtain a sum and difference pattern.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of a phased array antenna module (reception system) 10 of an antenna device according to an embodiment of the present invention, where 1 is an element antenna for receiving a radio wave, and 2 is a radio wave received by an element antenna 1. Is a frequency discriminator that identifies and distributes the frequency of the signal amplified by the low-noise amplifier, and has a function of separating an RF signal in this case. Also, 4
Reference numerals “a” and “4b” denote analog or digital phase shifters for giving a phase shift to each output divided into two frequencies by the frequency discriminator 3. In the figure,
S1 indicates a signal from the satellite 1S, and S2 indicates a signal from the satellite 2S. The antenna device according to the present embodiment includes an array antenna 1A in which element antennas 1 are arranged in a matrix of n rows × m columns as shown in FIG. 2A, and an array antenna 1A as shown in FIG. A plurality of phased array antenna modules 10 each including the above-described element antennas 1 are provided to achieve multi-beams. In the figure,
Elevation (El) in the row direction (left and right directions in the figure)
The azimuth (A)
z) The axial direction.

Next, the operation of the phased array antenna module (receiving system) having the above configuration will be described. As shown in FIG. 1, a signal of frequency f1 is incident from satellite 1S at an angle θ1 with respect to the normal direction of element antenna 1, and a signal of frequency f2 is incident at an angle θ2 from satellite 2S. I do. Also, a linear array is assumed as an array antenna 1A including a plurality of element antennas 1. This is because it is sufficient to consider that the linear array is aligned with the orbital direction when considering access to the polar orbiting satellite in the antenna device. Further, the antenna device is provided with signals S1, S2 from the two satellites 1S, 2S.
S2 shall be received at the same time. FIG. 3 is a diagram for explaining the operation principle of the array antenna 1A having the linear array configuration, and shows a state in which the array antenna 1A is receiving a signal arriving from the satellite 1S. In the figure,
1 is an element antenna constituting the array antenna 1A, 4 is a phase shifter connected to each element antenna 1, and 11 is a power combining circuit for combining signals from the phase shifters 4 described above.
The symbol W1 is the phase wavefront from the satellite 1S, and the symbol W2 is the satellite 2S
From the phase wavefront. Here, the phase shifter 4 changes the phase wavefront of the array antenna 1A by the symbol W10 in FIG.
As shown in (1), by performing phase matching so as to receive a signal from the satellite 1S, the signal coming from the satellite 1S can be combined in the power combining circuit 11. In the phase matching, the distance between the element antennas 1 is d, and the arrival direction (incident angle) of the signal from the satellite 1S is θ1.
Then, the phase difference φ between adjacent antenna elements becomes φ =
(2πf / c) d · sin θ1 (c: speed of light) is used to set the phase shift angle of each phase shifter 4. Therefore, the signal arriving in the other direction, that is, the signal arriving from the satellite 2S does not have the same phase wavefront (does not satisfy the co-phase condition) in the above setting, so that the signals are canceled by the power combining circuit 11 and the signal is not combined from the satellite 2S. Will be.

In the array antenna 1A, since the beam width of each element antenna is wide, a signal from the satellite 2S is also received at the actual element antenna level. Therefore,
If the reception signal from the satellite 2S is taken out and the co-phase condition is satisfied, the beam of the satellite 1S and the beam of the satellite 2S can be taken out at the same time. That is, in the first embodiment, as shown in FIG. 1, two phase shifters 4a and 4b are set for each element antenna 1, and the signal from the satellite 1S amplified by the low noise amplifier 2 and the satellite The signal from 2S is distributed by the frequency discriminator 3 to two frequencies, ie, the beam frequency of the satellite 1S and the beam of the satellite 2S, and sent to the phase shifters 4a and 4b, respectively. The phase shifters 4a and 4b independently apply phase shifts to perform phase matching, whereby beams of the satellite 1S and satellite 2S having different frequencies can be simultaneously extracted.

In the first embodiment, for simplicity, the case where two beams, that is, the beam of the satellite 1S and the beam of the satellite 2S are received has been described, but the same applies to the case where there are three or more received beams. It goes without saying that a plurality of beams can be extracted simultaneously by the configuration described above. Also, since the reversible theorem holds for the characteristics of the antenna, the basic configuration of the phased array antenna module is the same for the transmission system and the reception system. Therefore, when the phased array antenna module 10 is a transmission module, in FIG. 1, 1 is an element antenna for transmission, and 2 is an RF amplifying an RF signal to be transmitted.
An amplifier is used, and 3 is a synthesizing circuit for synthesizing signals having different frequencies input through the phase shifters 4a and 4b. Two transmission signals having different frequencies are transmitted by the phase shifters 4a and 4b. After adjusting the phase based on the direction, the signal may be combined / amplified and transmitted from the element antenna 1. The signals transmitted from the element antennas of the array antenna 1A are combined in the air. At this time, in the direction of the satellite 1S, the signal of the frequency transmitted to the satellite 1S satisfies the co-phase condition, The signals do not satisfy the co-phase condition. Conversely, in the direction of the satellite 2S, the signal of the frequency transmitted to the satellite 2S satisfies the co-phase condition, but the signal of the frequency transmitted to the satellite 1S does not satisfy the co-phase condition. Therefore,
A signal having a frequency to be transmitted to the satellite 1S can be transmitted in the direction of the satellite 1S, and a signal having a frequency to be transmitted to the satellite 2S can be transmitted in the direction of the satellite 2S. (See FIG. 3).

Embodiment 2 FIG. In the first embodiment, the beam of the satellite 1S and the beam of the satellite 2S having different frequencies are simultaneously extracted. However, when the signal frequency of the satellite 1S and the signal frequency of the satellite 2S are the same, FIG. As shown, by providing the power divider 5 instead of the frequency discriminator 3 of FIG. 1, the beam of the satellite 1S and the beam of the satellite 2S having different electric powers of the radio wave reaching the array antenna 1A can be simultaneously extracted. . However, in this case, since power distribution is performed, finally, only half power can be extracted as the output level.

Embodiment 3 In the first embodiment, the beam of the satellite 1S and the beam of the satellite 2S are discriminated by the frequency discriminator 3 in the RF band. However, as shown in FIG.
A frequency converter 6 is provided downstream of the low-noise amplifier 2, and the satellite 1
The signal of the RF frequency (about several GHz) from S and 2S is used as the first IF frequency (about several hundred MHz) using the local oscillation signal L0.
After the conversion into the above-mentioned signal, the beam of the satellite 1S and the beam of the satellite 2S may be discriminated by the frequency discriminator 3A operating in the first IF frequency band. Frequency discrimination is
In general, it is easier to perform the operation in the first IF band having a lower frequency than in the RF frequency band in terms of the circuit configuration. For example, the operation can be performed using a filter using a lumped constant circuit and the resolution is good. Therefore, by down-converting the received signal to the first IF frequency and discriminating the frequency, the beam of the satellite 1S and the beam of the satellite 2S can be accurately separated and extracted.

Embodiment 4 In the third embodiment, the frequency discrimination is performed after down-converting the signal amplified by the low noise amplifier 2 to the first IF frequency using the frequency discriminator 3a operating in the first IF frequency band. As shown in FIG. 6, instead of the frequency discriminator 3A, the RF signal amplified by the low noise amplifier 2 is directly converted to a second IF frequency (baseband signal) using the local oscillation signal L0. Frequency discriminator 3 using frequency converter 7 with conversion function and operating at second IF frequency
By using B, the beam of the satellite 1S and the beam of the satellite 2S can be separated and extracted with higher accuracy.
The frequency converter 7 outputs the R
This is a frequency converter that converts the F signal into a baseband signal, and further directly converts I and Q channel signals, which are quadrature signals, for demodulating a phase modulation signal used very often in digital communication. The frequency discriminator 3B outputs two frequency-separated I and Q channel signals (I (f ′ in FIG.
1), Q (f'1) and I (f'2), Q (f'2)). Since the output from the frequency discriminator 3b is an I-channel signal and an Q-channel signal, instead of the phase shifters 4a and 4b, the vector converters 8a,
8b is used.

Embodiment 5 In the first embodiment, the received signal is divided into two frequencies by the frequency discriminator 3 and the respective outputs are independently phase-shifted by the phase shifters 4a and 4b.
The arrival directions of the S beam and the satellite 2S beam are θ
1, θ2, the frequencies are f1 and f2, and the direction of arrival and the frequency have a relationship as shown in the following equation (1):
As shown in FIG. 7, the satellite 1S is output by one phase shifter 4c.
And the beam of the satellite 2S can be extracted. f1sinθ1 = f2sinθ2１ (1) This is an equation that gives the phase wavefront of the signal, that is, the phase φ that directs the beam in a desired direction. The frequency of the signal is f, the arrival direction (incident angle) is θ, and the element antenna is Assuming that the interval is d, the following is obtained. φ = (2πf / c) d · sin θ (c; speed of light) ‥‥‥ (2) From the above equation (2), as a condition for obtaining the same φ as the beam of the satellite 2S as the beam of the satellite 1S, the following equation (3) It is sufficient that the frequency satisfies the condition shown in ()). f2 = f1 (sinθ1 / sinθ2) ‥‥‥ (3) Note that another satellite K satisfying fk = f1 (sinθ1 / sinθk)
It is needless to say that a beam can be extracted from. However, the above condition (3) requires that the difference (| θ1−θ2 |) between the different signal directions be 90 degrees or less, and when used as a communication satellite, the satellite is expected depending on the position on the earth. Due to the different angles, it is only applicable in certain areas.

As described above, since the basic configuration of the phased array antenna module is the same in the transmission system and the reception system, the phased array antenna module 10 of the second to fourth embodiments has the same configuration. It can be a transmission module.

Embodiment 6 FIG. FIG. 8 is a diagram showing a configuration of an array antenna 1A according to the sixth embodiment, where n rows × m
The phased array antenna module including the element antennas 1 in an arbitrary row and column, for example, p rows and q columns among the element antennas 1 arranged in a matrix of columns is described in the first to fourth embodiments (FIGS. 1 and 4). 4 to 7), one of the configurations for extracting two outputs from one element antenna 1 is adopted. For a phased array antenna module including another element antenna 1, a conventional one-element antenna is used. In this configuration, one output is taken out from the antenna.

Next, the operation will be described. Each phased array antenna module always receives a signal from the satellite 1S. On the other hand, the phased array antenna module including the p-row and q-column element antennas 1 always receives a signal from the satellite 1S and receives a signal from another satellite whose location is not determined (for example, the satellite 2S). And
The position of the satellite 2S is detected by performing beam scanning in the Az direction by beam-scanning the linear array of p rows and beam scanning in the El direction by beam-scanning the linear array of q columns. Thus, the array antenna 1
By configuring a module of an arbitrary row and column of A, for example, a module of p row and q column to take out two outputs, the satellite 1S
, The position of the satellite 2S whose location is not determined can be detected.

Embodiment 7 FIG. FIG. 9A is a diagram showing a configuration of an array antenna 1A according to the seventh embodiment. Among the element antennas 1 of the array antenna 1A arranged in a matrix, upper, lower, and oblique lines shown in FIG. The phased array antenna module including the left and right symmetric four element antennas 1a, 1b, 1c, 1d is the one element antenna shown in the first to fourth embodiments (FIGS. 1, 4 to 7). The phased array antenna module including another element antenna 1 may be configured to take out one output from a conventional one-element antenna. A radio wave is generated by a sum and difference pattern of element antennas 1a and 1c provided at positions symmetrical with respect to the center point of the antenna, or a sum and difference pattern of element antennas 1b and 1d. Calculates the arrival direction, the antenna elements 1a, 1b, 1
The so-called tracking error pattern of the module pulse antenna is obtained from the sum and difference patterns of c and 1d. Thereby, a direction error can be detected. However, in this case, a frequency different from the signal frequency is used. For example, in the case of using a satellite, a beacon wave can be used.

[0025]

As described above, according to the first aspect of the present invention, a frequency discriminating circuit for distributing signals having different frequencies received by an element antenna, and the frequency discriminating circuit connected to the frequency discriminating circuit. And a plurality of phase shifters that independently apply a phase shift to each of the signals having different frequencies output from the control section, so that a plurality of signals having different frequencies can be received.

According to the second aspect of the present invention, a plurality of phase shifters for independently giving a phase displacement to each of a plurality of transmission signals having different frequencies transmitted from the element antenna;
Since a combining circuit for combining the outputs of the phase shifters is provided, a plurality of transmission signals having different frequencies can be transmitted from each element antenna.

According to the third aspect of the present invention, a power divider for distributing signals having different powers received by the element antenna is provided in place of the frequency discriminating circuit. Can be received.

According to the fourth aspect of the present invention, since the frequency converter for converting the frequency of the RF signal into the signal of the first IF frequency is provided at the preceding stage of the frequency discriminating circuit, the frequency discrimination is performed at the first IF frequency. This can be performed in a band, and a plurality of signals can be accurately separated and extracted.

According to the fifth aspect of the present invention, since the frequency converter for directly converting the frequency of the RF frequency signal into the I and Q channel signals, which are baseband signals, is provided before the frequency discriminating circuit. Can be performed in a baseband signal band, and a plurality of signals can be separated with higher accuracy.

According to the sixth aspect of the present invention, one phase shifter is provided for an incoming signal having a plurality of different frequencies such that the relationship between the direction and the frequency of the incoming signal satisfies fasin θa = fbsinθb. After the incoming signals are phase-shifted by the phase shifter and distributed to signals of a plurality of frequencies, a plurality of signals having different frequencies can be received with a simple configuration.

According to the seventh aspect of the present invention, a plurality of signals can be received by the element antennas in a specific column and a specific row, and a plurality of signals can be always received by a phase shifter. Since a phase for performing beam scanning is given to an unarrived incoming signal, a signal from a predetermined satellite is always received, and a position of a satellite whose location is not determined can be detected.

According to the present invention, a plurality of signals can be received by a plurality of element antennas provided at positions symmetrical with respect to the center point of the array antenna. Since the outputs of the element antennas are combined in phase and in opposite phases to obtain a sum and difference pattern, it is possible to detect the arrival direction and the direction error of the radio wave.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a phased array antenna module according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of an array antenna according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation principle of an array antenna having a linear array configuration.

FIG. 4 is a diagram showing a configuration of a phased array antenna module according to Embodiment 2 of the present invention.

FIG. 5 is a diagram showing a configuration of a phased array antenna module according to Embodiment 3 of the present invention.

FIG. 6 is a diagram showing a configuration of a phased array antenna module according to Embodiment 4 of the present invention.

FIG. 7 is a diagram showing a configuration of a phased array antenna module according to Embodiment 5 of the present invention.

FIG. 8 is a configuration diagram of an array antenna according to a sixth embodiment of the present invention.

FIG. 9 is a configuration diagram of an array antenna according to a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional phased array antenna.

FIG. 11 is a diagram showing a configuration of a conventional antenna device.

[Explanation of symbols]

1, 1a, 1b, 1c, 1d element antenna, 1A array antenna, 2 low noise amplifier, 3, 3A, 3B frequency discriminator, 4a, 4b, 4c phase shifter, 5 power divider, 6 frequency converter, 7 Frequency converter with direct conversion function, 8a, 8b vector converter, 10 phased array antenna module, 11 power combining circuit.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5J021 AA05 AA09 AA11 AB06 CA03 DB02 DB03 FA06 FA17 FA32 GA02 HA02 HA04 HA05 JA03 JA07 5K004 AA05 FA11 FH06 5K062 AA09 AC01 AE03 AE04 BE07 BE08

Claims (8)

[Claims] 1. An antenna device having an array type antenna comprising a plurality of element antennas, a frequency discrimination circuit for distributing signals having different frequencies received by said element antennas, and said frequency output from said frequency discrimination circuit. An antenna device comprising: a receiving system including a plurality of phase shifters that independently apply a phase shift to each of the different signals. 2. An antenna device comprising an array type antenna comprising a plurality of element antennas, wherein a plurality of phase shifts for independently giving a phase shift to each of a plurality of transmission signals having different frequencies transmitted from said element antenna. An antenna device comprising: a transmission system including a phase shifter and a synthesis circuit for synthesizing the outputs of the phase shifters. 3. The antenna device according to claim 1, further comprising a power divider for distributing signals having different powers received by the element antenna, instead of the frequency discriminating circuit. 4. A frequency converter for distributing a signal of a first IF frequency band, wherein said frequency discriminating circuit is a frequency converter for converting a signal of an RF frequency into a signal of a first IF frequency at a stage preceding said frequency discriminating circuit. The antenna device according to claim 1, further comprising: 5. The frequency discriminating circuit is a frequency discriminating circuit for distributing I and Q channel signals, which are baseband signals, and a frequency conversion circuit directly converts an RF frequency signal into the I and Q channel signals before the frequency discriminating circuit. The antenna device according to claim 1, further comprising a frequency converter that performs the conversion. 6. The relationship between the direction of an incoming signal and the frequency is fas.
For an incoming signal having a plurality of different frequencies that satisfy inθa = fbsinθb, a single phase shifter is used, and a phase shift is given to each of the incoming signals by the phase shifter. The antenna device according to claim 1, wherein the antenna device is distributed to the antenna device. 7. The device according to claim 1, wherein the element antenna is an element antenna in a specific column and a specific row, and is configured to give a phase for performing beam scanning on an incoming signal which is not always received. The antenna device according to claim 1 or any one of claims 3 to 5. 8. The element antennas are a plurality of element antennas provided symmetrically with respect to a center point of an array antenna, and outputs of the respective element antennas are in-phase combined and out-of-phase combined to sum and sum. 6. The method according to claim 1, wherein a difference pattern is obtained.
The antenna device according to any one of the above.