JPH03157002A - Array antenna system - Google Patents

Abstract

PURPOSE:To attain a reception front end in a form of a module by mixing a reference signal to a feeding system of each antenna element in loose coupling and correcting a frequency and phase shift between intermediate frequency conversion outputs by each independent local oscillator from a reception signal of each array element based on the reference signal. CONSTITUTION:Outputs of antenna elements 1-3 and a pilot signal mixed via couplers 4-6 from an oscillator 7 are converted into a 1st intermediate frequency signal by frequency converters 8-10, a local oscillating frequency of each frequency converter is not completely identical and the 1st intermediate frequency signal differs by the difference. Voltage variable local oscillators 14, 15 control a 2nd intermediate frequency being the output of mixers 11, 12 of the same frequency and phase as the output frequency of the mixer 18 to make the difference zero. A pilot signal extracted from the control voltage by band pass filters 17-19 is subject to phase comparison by phase detectors 20, 21 and smoothed by low pass filters 22, 23. The operation is established by the pilot signal and when the frequency of the output signal of the antenna element does not differ much from the frequency of the pilot signal, the operation is established at the same time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an array antenna, and in particular to a phased array or a phased array that changes the direction or shape of a beam by controlling the phase between the signals of each antenna element of the array antenna. This invention relates to an adaptive array antenna.

(Summary of the Invention) The present invention relates to phase control between signals of each antenna element of an array antenna, and is applicable to an array antenna device in which each element of the array antenna is frequency-converted at an independent receiving front end and synthesized in an intermediate frequency band. An extremely small reference signal is mixed into each antenna element or its feeding system as a loose couple, and using this signal as a reference, the frequency and phase shift between the intermediate frequency conversion output of each independent local oscillator of the received signal of each array element is calculated. It is configured to detect and correct.

In this way, the problems of local oscillation signal distribution in the conventional common local oscillation system are solved, the receiving front end section can be modularized, and the array configuration can be made easy and inexpensive.

(Prior Art) A phased array antenna or an adaptive array antenna has conventionally provided a phase shifter after each antenna element constituting the array, and achieved a predetermined directivity by controlling the amount of phase shift of this phase shifter. . Another method is to first convert to an intermediate frequency band with a frequency converter and then control the phase with a phase shifter or phase lock loop circuit for the intermediate frequency band. In this case, in order to maintain phase information, the frequency converter is The local oscillator was shared.

(Problems to be Solved by the Invention) In high frequency regions such as microwave and millimeter wave bands, there is a problem that the insertion loss of the above-mentioned phase shifter is large and the antenna gain is reduced. Further, when performing fine phase control in microwave or millimeter wave bands, there is a problem that the configuration of these phase shifters becomes complicated and expensive. To avoid these problems, the method of controlling the frequency by converting it to an intermediate frequency band using a frequency converter requires complicated and difficult installation of waveguides and coaxial lines for distributing local oscillation signals to each frequency converter. However, there was a problem in that it led to high costs.

Therefore, an object of the present invention is to solve the problem of local oscillation signal distribution in the common local oscillation method described above, and to make it possible to modularize the most expensive reception front-end part of a phased array antenna or adaptive array antenna, and to It is an object of the present invention to provide an array antenna device in which the array configuration is easy and inexpensive, and since control is performed in an intermediate frequency band, it is possible to make full use of advanced beam control technology such as digital forming technology.

(Means for Solving the Problems) In order to achieve this object, the first invention related to the array antenna device described in this specification provides an intermediate frequency band in which each element of the array antenna is frequency-converted by an independent receiving front end. In an array antenna device that is combined with a pilot signal of a different frequency that does not interfere with the received signal of the array antenna, the device has respective couplers that couple to respective feed portions of each antenna element, and a pilot signal of a different frequency that does not interfere with the received signal of the array antenna. means for exciting each of the couplers; and correction means for correcting the frequency and phase shift between the intermediate frequency outputs of the received signals from each of the antenna elements using another local oscillator or an infinite phase shifter, using the pilot signal as a reference. It is characterized by comprising the following.

Further, a second invention related to the array antenna device described in this specification is an array antenna device in which each element of the array antenna is frequency-converted by an independent reception front end and synthesized in an intermediate frequency band, in which the device has the following features: means having another antenna coupled to each antenna element and exciting the antenna with a pilot signal of another frequency that does not interfere with the received signal of the array antenna;
The apparatus is characterized by comprising a correction means for correcting the frequency and phase deviation between the intermediate frequency outputs of the received signals from each of the antenna elements using another local oscillator or an infinite phase shifter, using the pilot signal as a reference. It is.

(Examples) The present invention will be described in detail below by way of examples with reference to the accompanying drawings.

First embodiment (phased array antenna device) corresponding to the first invention related to the array antenna device described in this specification
A block diagram of the configuration is shown in FIG. This embodiment includes a plurality of (three in this case) antenna elements 1, 2.3, a coupler 4, 5.6 coupled to the feed section of the antenna element,
An oscillator 7 that generates a pilot signal whose frequency is preferably slightly different from that of the input radio wave; a frequency converter 8, 9, and 10 that frequency converts and amplifies both the output of each antenna element and the pilot signal; a mixer 11.12.13 for converting, a voltage variable local oscillator 14.15 supplying the local oscillation frequency of the mixer 11.12, and a local oscillator 16 supplying the local oscillation frequency of the mixer 13;
Bandpass filter 17 that extracts only the pilot signal frequency
．． 18.19, a phase detector 20.21 that performs phase discrimination of the pilot signal, and a low-pass filter 22.21 that smoothes the phase detection output and supplies it to the voltage variable local oscillator 14.15.
23, a variable phase shifter 24, 25 that changes the output phase of the mixer IL 12, a phase shift control circuit 26 that controls the amount of phase shift of this variable phase shifter, and each variable phase shifter and mixer 13.
and a synthesizer 27 that adds together the outputs of the two.

The outputs of antenna elements 1, 2.3 and pilot signals are converted to the first intermediate frequency by frequency converters 8, 9, 10, but since the local oscillation frequencies of each frequency converter are not completely the same, the difference between them is each first intermediate frequency is different.

In order to make this difference zero, in the device of the present invention, the second intermediate frequency of the outputs of mixer 11 and mixer 12 is controlled by variable voltage local oscillators 14 and 15 so that it has the same frequency and phase as the output frequency of mixer 13. The control voltage is obtained by comparing the phases of pilot signals extracted by bandpass filters 17, 18, 19 with phase detectors 20, 21, and smoothing them with low-pass filters 22, 23. If the phase of the pilot signal output of mixer 11.12 deviates from the pilot signal output of mixer 13, the frequency of the voltage variable oscillator changes to correct this phase deviation, forming a phase locked loop. Therefore, the outputs of mixers 11, 12, and 13 are completely in phase not only in frequency but also in phase. This operation holds true for the pilot signal, but it also holds true for the output signal of the antenna element if the frequency is not significantly different from that of the pilot signal. Therefore, the subsequent variable phase shifter 2
If the output phase of each antenna element is controlled by 4.25, this antenna device operates as a phased array antenna.

Next, a configuration block diagram of a second embodiment (monopulse antenna device) according to the first invention is shown in FIG. This embodiment includes an antenna element 3L 32, a coupler 33, 34 that couples to the feed section of the antenna element, and an oscillator 3 that generates a pilot signal that preferably has a slightly different frequency from the input radio wave.
5, frequency converters 36 and 37 that frequency convert and amplify both the antenna element output and the pilot signal, and an infinite phase shifter 38 that freely controls the output phase of the frequency converter 36.
, a bandpass filter 39, 40 that extracts only the pilot signal from this output and the output of the frequency converter 37, a phase detector 41 that compares the phases of these two extracted pilot signals, and a phase detector 41 that smoothes this output and converts it into an infinite A low-pass filter 42 that supplies the phase shifter 38, a 90 degree phase shifter 43 that delays the output phase of the frequency converter 37 by 90 degrees, and an output of the infinite phase shifter 38 and an output of the 90 degree phase shifter 43. It is configured to include a hybrid 44 that mixes and decomposes it into sum and difference components, and a mixer 45 that takes out the DC component by multiplying the sum and difference outputs.

The outputs of the antennas 31, 32 and the pilot signals are converted to intermediate frequencies by frequency converters 36, 37, the respective frequencies being offset by the frequency deviation of the local oscillator included in the frequency converter. This shift is corrected by continuously shifting the phase with an infinite phase shifter 38.

The control voltage of the infinite phase shifter 38 is determined by the bandpass filter 39.40.
The phases of the pilot signals extracted are compared by a phase detector 41 and smoothed by a low-pass filter 42. If the output of the infinite phase shifter 38 and the output of the frequency converter 37 are out of phase, the infinite phase shifter 38 becomes 1. Since the phase difference is reduced to zero, the in-phase condition is always guaranteed for the pilot signal. The in-phase condition is also guaranteed for the antenna element output signal as long as the frequency is not significantly different from that of the pilot signal. Therefore, the 90 degree phase shifter 43 converts one signal to 9
When the two signals are input to the hybrid 44 with a phase shift of 0 degrees, they are decomposed into sum and difference components, so by multiplying the sum and difference signals, a predetermined monopulse output signal can be obtained. .

Next, reference will be made to a second invention of the array antenna device according to the present specification, which is an embodiment of the first invention described above, in which the pilot signal from the oscillator 7 or 35 is outputted to the antenna element through a coupler. Instead of loosely coupling the pilot signal to the received signal, it is sufficient to prepare a separate antenna, transmit the pilot signal with it, and receive the output at each antenna element.

Therefore, further detailed explanation will be omitted.

Although the embodiments of the array antenna device of the present invention have been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the gist of the invention. It will be obvious to the business operator.

(Effects of the invention) The field of mobile radio communication and mobile reception of broadcasting is currently undergoing major development, and one of the important technologies supporting this development is the ability to freely manipulate antenna beams to increase sensitivity and prevent interference. There are beam steering antenna technologies that reduce the This antenna has the feature that the beam shape and direction can be arbitrarily set by controlling the excitation amplitude and phase of a large number of antenna elements, but a variable phase shifter and a variable amplifier are required for each antenna element. Configuring these devices in high frequency bands such as microwave or millimeter wave bands would be extremely disadvantageous in terms of accuracy and cost, so it is better to convert to a lower intermediate frequency band and control the phase and amplitude. Common. When performing this frequency conversion, a common local oscillator output must be used for all elements to preserve phase information. Distributing the local oscillation output of microwaves and millimeter waves to each frequency converter using a waveguide or coaxial line is undesirable in terms of antenna configuration, cost, reliability, and maintenance adjustment.
This has hindered the advancement of beam steering antennas into consumer equipment.

In contrast, in the device of the present invention, a completely independent frequency converter can be used, so that the antenna element and the receiving front end section can be integrated into a mosier configuration. Also, when applied to mobile satellite broadcasting receiving equipment,
Since a commercially available inexpensive S converter can be used as is, the system cost is reduced, which greatly contributes to its widespread use.

[Brief explanation of the drawing]

FIGS. 1 and 2 respectively show a first embodiment configuration Pronk diagram and a second embodiment configuration Pronk diagram corresponding to the first invention related to an array antenna device. 1, 2. 3.31.32... antenna element 4,
5. 6.33.34... Coupler 7.35... Oscillator (for pilot signal) 8, 9.10.36.37.
...Frequency converter 11, 12.13.45...Mixer 14, 15.16...Local oscillator 17, 1B, 19.39.40...Band filter 2
0, 21.41...Phase detector 22, 23.42...Low pass filter 24, 25...Variable phase shifter 27...Synthesizer 43...90 degree phase shifter 26...・Phase shift control circuit 38...Infinite phase shifter 44...Hybrid Figure 1 '1+Glue ((phased antenna 3A1) Figure 2

Claims (1)

[Scope of Claims] 1. In an array antenna device in which each element of the array antenna is frequency-converted by an independent receiving front end and synthesized in an intermediate frequency band, the device provides a power supply section for each antenna element. having respective couplers for coupling, and
means for exciting each of the couplers with a pilot signal of a different frequency that does not interfere with the received signal of the array antenna, and a frequency between the intermediate frequency outputs of the received signals from each of the antenna elements, with this pilot signal as a reference; and a correction means for correcting the phase shift using another local oscillator or an infinite phase shifter. 2. In an array antenna device in which each element of the array antenna is frequency-converted by an independent receiving front end and synthesized in an intermediate frequency band, the device has another antenna coupled to each antenna element, and means for exciting the antenna with a pilot signal of a different frequency that does not interfere with the received signal of the antenna; and a means for exciting the antenna with a pilot signal of a different frequency that does not interfere with the received signal of the antenna; An array antenna device comprising: correction means for correcting using a local oscillator or an infinite phase shifter; 3. The array antenna device according to claim 1 or 2, wherein a frequency difference between the frequency of the pilot signal and the received signal is extremely smaller than the frequency of the received signal.