JPS6224703A - Adaptive antenna system - Google Patents

Abstract

PURPOSE:To attain miniaturization and light weight of an adaptive circuit by using a difference signal in a sum signal and the difference signal outputted from a sub array antenna so as to apply the signal to the adaptive circuit thereby constituting a side lobe canceller circuit. CONSTITUTION:The array antenna comprising N-element of antennas A1-AN to each of which a phase shifter 2 is provided consists of M-set of sub arrays S1-SM. Each sub array consists of an Li (i=1, 2...M) and each sub array has each sub combiner 3. The sub combiner consists of a 180 deg. hybrid circuit and gives a sum signal output SIGMA and a difference signal output DELTA. Further, the sum signal becomes an output (y) to the array antenna by the combiner 4 to M-set of signals to suppress an undesired component and the result is inputted to an adaptive circuit 5. Signals x1-xk in the difference outputs DELTA of each sub array are inputted to the adaptive circuit 5 to constitute the side lobe canceller circuit, a zero point is made in the disturbing wave direction, resulting in obtaining an output signal Z.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adaptive antenna device in which an array antenna is composed of a plurality of subarrays, and the subarrays are provided with an adaptive function.

(Prior art) In an adaptive antenna in which the elements constituting an array antenna are provided with an adaptive function, the method of providing the adaptive function to all antenna elements has the disadvantage of being expensive due to the large number of inputs and the complexity of the device. . Therefore,
As shown in Fig. 4, array antenna AI, At...A
, are subarrays (St, S
g...SM), each array antenna has a phase shifter 2, and the sub-array has a sub-array combiner 3.
The signals from each sub-combiner 3 are collected in a co/piner 4-, and the received signals are supplied to the adaptive circuit 5 through the adaptive circuit 5. In this case, some outputs of the subarrays (xl・
xi...xk) to the adaptive circuit 5 to configure a sidelobe canceller circuit with an adaptive function.

(Problem to be Solved by the Invention) However, even with this method, depending on the directivity of the subarray that provides the adaptive function and the positional issues of the selected elements and subarrays, the zero point of the directivity in the direction of the interference wave may be created. Although it is possible, it has the disadvantage that the characteristics of the main beam are significantly deteriorated.

(Means for Solving the Problems) In order to eliminate these drawbacks, the present invention uses a difference signal that creates a zero point in the main beam direction among the outputs of the subarrays, and eliminates side lobes without causing deterioration of the main beam. It consists of an adaptive circuit with canceller capability. This will be explained in detail below with reference to the drawings.

FIG. 1 shows a configuration diagram of an embodiment of the present invention.

Phase shifter 2 is installed (in some cases there is no phase shifter)
The array antenna consisting of N-element antennas A1 to APIIJ1 is composed of 1M subarrays 81 to SM. Each of these subarrays is Li (i=1, 2...M)
Each sub-array has a sub-combiner 3. This sub-combiner is composed of, for example, a 180° hybrid circuit and provides a sum signal output Σ and a difference signal output Δ. Furthermore, the sum signal is output y of the array antenna by the combiner 4 for M signals, and is input to the adaptive circuit 5 to suppress unnecessary components. On the other hand, signals x1 to xK of the difference output Δ of each sub-array are input to the adaptive circuit 5, which constitutes a sidelobe canceller circuit, performs an operation to create a zero point in the direction of the interference wave, and obtains an output signal Z as a result. .

The effects of the nine aspects of the present invention configured as described above are shown by computer simulation as follows. Here, as a calculation example, the number of elements is U, the element spacing is 0.5λ (λ: wavelength), and a linear array antenna is constructed of 4 elements with the phase shifter 2 adjusted so that it is fed with uniform distribution and scans in the front direction. A sidelobe canceller configured by forming six subarrays and using the difference signal output of one of the subarrays will be described.

Figure 2 shows the directivity of the subarray, with a zero point in the front direction.
Figure 3 shows the results of creating a zero point for interference waves from the 12° direction. . Although the above description is based on the case where the array antennas are arranged in a straight line, the same effect can be obtained when the array antennas are arranged in c rows on the plane.

(Effects of the Invention) As explained above, the present invention uses the difference signal of the sum signal and difference signal output from the subarray antenna to supply it to the adaptive circuit and configure the sidelobe canceller circuit, thereby forming a subarray. This adaptive array antenna has an economical advantage because the adaptive circuit can be made smaller and lighter without deteriorating the characteristics for the main beam.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an adaptive array antenna according to an embodiment of the present invention, Fig. 2 is a directivity side view of a sub-array consisting of 4 elements, and Fig. 3 is a calculation when the present invention is applied to a 24-element array. In the example, subarray 1 consists of 4 elements.
A directional side view in which interference waves in the 12° direction are suppressed using
FIG. 4 is a configuration diagram of a conventional sub-arrayed adaptive array antenna. A, -A2... Antenna element, 2... Phase shifter, 3.
... Combiner for sub-array, 4... Combiner, 5
...Adaptive circuit, 6...Dummy patent applicant
Japan Radio Co., Ltd. M1 diagram M2 diagram angle (degl)

Claims (1)

[Claims] 1. An adaptive antenna device comprising a sidelobe canceller circuit using a difference signal of sum and difference signals output from any of the subarrays in a plurality of subarrayed array antennas.