JPH0831737B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used in various wireless communication devices and radar devices, and is received in a side lobe region of a beam in a desired direction when receiving a radio wave. The present invention relates to an antenna device having a side lobe canceller function for canceling unnecessary waves.

(Prior Art) Usually, a sidelobe canceller (SLC) refers to an antenna device that cancels an unwanted wave received in a sidelobe region of a main antenna by using a response of an auxiliary antenna to the unwanted wave. An example of such an antenna device is shown in FIG.

That is, as shown in FIG. 4, this antenna device includes an array antenna 10 which is composed of antenna elements 11 to 1n and forms the main antenna, and a signal (actually, received by each element of the array antenna 10 (actually, For the main beam forming circuit configured by including an adder 20 for adding and summing required signals (phase-shifted signals) via an appropriate phase shifter, for example, an auxiliary antenna 31 which is composed of three elements here. , 32, 33, and the main beam forming circuit for each of the signals received by these auxiliary antennas 31, 32, 33 (this is also the signal that has been phase-shifted as required through the phase shifter) The correlation processor 40 for calculating the correlation with the main beam signal formed in (which is achieved by integrating the multiplication value of each auxiliary antenna reception signal (auxiliary beam signal) and the main beam signal), and the auxiliary This is applied to each received signal of antenna 31, 32, 33. Each corresponding operation value weighter for performing each separate weighting according to (correlation value)
51, 52, 53 and an auxiliary beam forming circuit having an adder 60 for adding and combining these weighted signals to form an auxiliary beam signal for the aforementioned unwanted wave. By subtracting the auxiliary beam signal from the beam signal, the above-mentioned unnecessary wave cancellation is realized.

(Problems to be Solved by the Invention) Generally, the auxiliary antennas 31, 32, and 33 as described above should have a gain equivalent to the side lobe level of the array antenna 10 forming the main antenna. Ten
Is a plane array antenna as shown in FIG. 5, the auxiliary antennas 31, 32, 33 are
As shown in FIG. 5, a small antenna having a structure arranged around it is used.

By the way, in this case, if the array antenna (planar array antenna) 10 forming the main antenna is relatively small or has a low sidelobe level, the auxiliary antennas 31, 32, 33 are the above Even if it is small, such an array antenna
Since the side lobe level of 10 can be covered, it is possible to remove the above-mentioned unwanted waves, but when it is not so, that is, when the array antenna 10 is large or has a high side lobe level. However, the gains of the auxiliary antennas 31, 32, and 33 are insufficient, and it becomes difficult to sufficiently remove unnecessary waves by these auxiliary antennas.

In order to solve such inconvenience, the auxiliary antenna may be a large antenna, but it is not preferable to make these auxiliary antennas large due to the constraints of the size and mass of the entire antenna.

In view of such circumstances, an object of the present invention is to provide an antenna device capable of satisfactorily removing any unwanted wave with a small-scale configuration without affecting the size or mass of the entire antenna. To do.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, a part or all of the elements of the array antenna forming the main antenna are also used as auxiliary antennas, and the elements of the array antenna receive the elements. A beam forming means for forming a plurality of beam signals corresponding to the respective signals using any of a plurality of the formed signals, and a part or all of the formed beam signals for assisting in canceling the unwanted wave. It is used as a beam signal.

(Operation) As described above, by using a part or all of the elements of the array antenna forming the main antenna as the auxiliary antenna, the gain as the auxiliary antenna can be arbitrarily set, and in any case Also, the side lobe level of the main antenna can be well covered, and sufficient unnecessary waves can be removed. Moreover, in this case, if the signal received by each element of the array antenna is converted into an appropriate digital signal in advance, it can be used as a main beam forming signal and an auxiliary signal without lowering the level of the received signal. The signal for beam forming can be well distributed. However, as the beam forming means, a signal received by each element of the array antenna is subjected to analog Fourier transform to form one beam signal as the main beam and a plurality of beam signals as the auxiliary beams. If the output Butler matrix circuit is adopted, it is not necessary to convert the received signal into a digital signal.

(Embodiment) FIG. 1 shows an embodiment of an antenna device according to the present invention.

As shown in the figure, in the antenna device of this embodiment, a part of the array antenna 10 (11 to 1n) forming the main antenna (elements 12 to 1 (n-1) in this example) is used as an auxiliary antenna. Combined use.

In the apparatus of this embodiment, the receiver 110 (111 to 11
n) is a well-known circuit for converting a high frequency signal received by each element 11 to 1n of the array antenna 10 into an intermediate frequency signal separately, and an analog / digital converter (hereinafter referred to as A / D).
A D converter) 120 (121 to 12n) is a well-known circuit that further converts the received signals converted into these intermediate frequency signals into digital signals of appropriate bits, and a phase shifter (digital phase shifter) 130. (131 to 13n) is a circuit that appropriately performs arithmetic processing on the reception signals converted into these digital signals to scan the reception beams formed below, and shifts the phases as required. element
The signals received by 11 to 1n are converted into an intermediate frequency signal by these receivers 110, further converted into a digital signal by the A / D converter 120, and the above-mentioned phase shift processing is performed by the phase shifter 130. After this, the signals corresponding to the above-mentioned main / auxiliary antenna elements 12 to 1n among them are respectively distributed to the main beam forming circuit and the auxiliary beam forming circuit as main and auxiliary beam forming signals. By the way, the decomposition is a distribution in digital values, and such a distribution does not cause any power loss in the received signal.

Now, in the main beam forming circuit, the phase shift processing signals corresponding to the dedicated elements 11 and 1n as the main antenna and the distributed signals are respectively received by the amplitude setting device 140 (141 to 14n) including a digital attenuator or an amplifier. Then, the initial level of the side lobe of the main beam is preset through the setter 140 to be formed, and then the outputs of these setters are added and synthesized by the digital adder 150 to obtain the antenna output corresponding to the main beam signal. .

On the other hand, the auxiliary beam forming circuit forms a plurality of auxiliary beams having a gain capable of covering the sidelobe level of the main beam based on the distributed signals. In addition, this auxiliary beam forming circuit forms the beam signal so as to have a null in the peak direction of the main beam which is the desired wave direction when forming such an auxiliary beam.

That is, the beam forming circuit 210 in the auxiliary beam forming circuit is composed of, for example, a fast Fourier transform (FFT) circuit, and based on the distribution signal, for example, orthogonal multi-beams (levels of beams at the same angle as shown in FIG. This is a circuit that forms and outputs a beam) SM ₀ that will be zero when multiplied and the angle integrated. In this case, examples of the orthogonal multi-beam, and be formed beam coincides with the direction of the main beam MB indicated by broken line in FIG. 2, or beam SB _M as indicated by the dashed line in the Figure 2 at the same time made, but in the beam forming circuit 210, the need to form an auxiliary beam with a null (null) in the peak direction of the above as the main beam (MB), this for beam signal corresponding to the beam SB _M are excluded To do. If the unwanted waves are removed by using the auxiliary beam formed and output as the orthogonal multi-beam SM ₀ as described above, the response in the desired wave direction as the antenna device can be kept constant, and as a result, the SN of the antenna output can be maintained. The ratio (S / N) can also be improved. Incidentally, in FIG. 2, since the angle sine (sin θ) is taken as the horizontal axis, the beam widths of the beam SM ₀ are all equal, but the angle θ itself is taken as the horizontal axis. In the case of the above, the beam width becomes wider as the distance from the central portion increases.

The level determination circuit 220 is a circuit that compares the levels of a large number of beam signals corresponding to the orthogonal multi-beams SM ₀ output from the beam forming circuit 210 in this way and performs the level determination, and the selection circuit 230 is the same. Beam forming circuit 2
A number (m in this example) of a particularly high level with respect to unwanted waves in the numerous beam signals output from 10
This is a circuit for selectively outputting only the beam signal of (1) based on the determination information by the level determination circuit 220. That is, only the beam signals thus selected are similar to the device shown in FIG. 4 above, but here digitally correlated with the main beam signal by the correlation processor 240 and weighted respectively. 250 (251 to 25m) after the required weighting based on each corresponding correlation value, then the adder
Additive synthesis is performed through 260.

As described above, by providing the level determination circuit 220 and the selection circuit 230, the number of auxiliary beams to be actually controlled can be arbitrarily reduced, and the number of the auxiliary beams that can be controlled is limited due to the device configuration. Even in some cases, it is possible to cope with this by effectively utilizing such a function of the apparatus of the embodiment. Subtractor 160
As in the device shown in FIG. 1, the cancellation of the unwanted wave is realized by subtracting the composite signal of the auxiliary beam signals, which is controlled as required, from the main beam signal.

As described above, according to the antenna device of the embodiment shown in FIG. 1, 1) it is possible to provide a minimum antenna configuration in which a part of the main antenna is also used as the auxiliary antenna.

2) Also, this allows the gain of the auxiliary antenna to be sufficiently maintained.

3) Moreover, with such an antenna configuration, even when the main beam forming signal and the auxiliary beam forming signal are distributed, the gain of the signal received by each of these antennas does not decrease.

4) The number of auxiliary beams to be actually controlled can be arbitrarily set, and the number of auxiliary beams can be significantly reduced.

 Many excellent effects such as etc. can be obtained.

In the above embodiment, a part of the array antenna 10 forming the main antenna (the part of the elements 12 to 1 (n-1)) is also used as the auxiliary antenna, but this is also used as the auxiliary antenna. Of course you can do it. By the way,
In the above-mentioned device, it is preferable that adjacent antennas be selected at equal intervals as the dual-purpose antennas.

Further, if the antenna device is capable of controlling many auxiliary beams in the device configuration, the level determination circuit 220
Alternatively, the selection circuit 230 may be deleted, and the same control (weighting control) may be performed on all the auxiliary beam signals formed and output by the beam forming circuit 210.

By the way, in the above embodiment, the main beam forming circuit and the auxiliary beam forming circuit are separately configured, and
Regarding the side lobe level of the main beam before suppressing unwanted waves, we have shown a device that can arbitrarily set this through the amplitude setting device, but the side lobe level of the main beam may be the same as the side lobe level of the auxiliary beam. If, for example, as shown in FIG. 3, the one that matches the desired direction beam of the orthogonal multi-beam formed by the beam forming circuit 210 to an FFT arithmetic circuit beam SB _M (No. It is also possible to use this as the main beam without excluding the beam shown by the one-dot chain line in FIG.

When the configuration shown in FIG. 3 is used, a Butler matrix circuit composed of an analog circuit is used as the beam forming circuit 210 instead of the FFT arithmetic circuit, and Fourier transform is performed by the Butler matrix circuit. For example, at least for the A / D converter 120 (121 to 12n), only the analog circuit that does not require it, that is, all the circuits after the phase shifter 130 (131 to 13n) are configured as analog specifications to configure the antenna device You will be able to. Of course, also by this, the main element and the auxiliary beam can be formed by using the same element for the main beam and the auxiliary beam, respectively, and these main beam and the auxiliary beam can be collectively processed through the Butler matrix circuit (beam forming circuit 210). Therefore, the gain of the signal received by the antenna does not decrease when the main and auxiliary beams are formed.

[Effects of the Invention] As described above, according to the present invention, unnecessary waves can be removed with high efficiency with a small-scale configuration without affecting the size or mass of the antenna as a whole.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an antenna device according to the present invention, FIG. 2 is a diagram showing an example of a beam mode formed by a beam forming circuit of the embodiment device, and FIG. FIG. 4 is a block diagram showing another embodiment of the antenna device according to the invention, FIG. 4 is a block diagram showing an example of a conventional antenna device having a sidelobe canceller function, and FIG. 5 is a diagram showing the antenna device shown in FIG. 3 is a schematic diagram showing an example of an antenna structure. 10 (11 ~ 1n) ... array antenna, 110 (111 ~ 11n) ...
… Receiver, 120 (121-12n) …… A / D converter, 130 (131-
13n) …… Phase shifter, 140 (141 to 14n) …… Amplitude setter, 15
0,260 …… Adder, 160 …… Subtractor, 210 …… Beam forming circuit, 220 …… Level judgment circuit, 230 …… Selection circuit, 240
...... Correlation processor, 250 (251-25m) …… Weighter.

Claims (5)

[Claims] 1. An unnecessary wave received in a side lobe region of a main beam formed on the basis of a signal received by each element of an array antenna is weighted as required based on a correlation with the main beam. An antenna device having a sidelobe canceller function of canceling by using a response of an auxiliary beam signal to the separately formed unnecessary wave, wherein any plural of signals received by each element of the array antenna are used. Beam forming means for forming a plurality of beam signals corresponding to each of these signals, and from among the formed beam signals, several beam signals having a particularly strong relationship with the unwanted wave are provided according to the radio environment at any time. An antenna device that uses the selected beam signal as an auxiliary beam signal for canceling the unnecessary wave. 2. A signal used for forming the main beam and the auxiliary beam is a digital signal obtained by subjecting a signal received by each element of the array antenna to a required analog / digital conversion, and the beam forming means, Fast Fourier transforming means for forming an orthogonal multi-beam signal based on these digital signals, wherein the selecting means selects a beam signal other than a beam signal that matches the direction of the main beam among the formed orthogonal multi-beam signals. The antenna device according to claim (1), which receives and selectively outputs some of these received beam signals having a particularly high level as auxiliary beam signals for canceling the unnecessary wave. 3. The antenna device according to claim 2, wherein one orthogonal multi-beam signal which is formed by the beam forming circuit and which is not input to the selecting means is used as a signal of the main beam. 4. The beam forming circuit Fourier-transforms a signal received by each element of the array antenna to obtain one beam signal as the main beam and a plurality of beam signals as the auxiliary beams, respectively. The antenna device according to claim (1), which is a Butler matrix circuit for forming and outputting. 5. An unnecessary wave received in a side lobe region of a main beam formed on the basis of a signal received by each element of an array antenna is weighted as required based on a correlation with the main beam. An antenna device having a sidelobe canceller function of canceling by using the response of an auxiliary beam signal to the separately formed unnecessary wave, the receiving device converting each signal received by each element of the array antenna into an intermediate frequency signal. , An analog / digital converter for converting the received signals converted into these intermediate frequency signals into digital signals, a phase shifter for shifting the received signals converted into these digital signals as necessary, and these phase shifters. A beam forming means for forming a plurality of beam signals according to the respective signals by using an arbitrary plurality of phased received signals For example, an antenna apparatus using a beam signal the formed as an auxiliary beam signal for the unnecessary wave cancellation.