JPH0465688A - Antenna system - Google Patents

Abstract

PURPOSE:To shorten the processing time for generating a multibeam by processing complex signals of respective element antennas of the antenna system of a holographic radar, which generates the multibeam, by Fourier transformation by the sides of a polygon. CONSTITUTION:The complex signals from receiving means 2 connected to the MXS element antennas arranged on the flanks of the prism in the circumferential direction in constant periodic array are processed by Fourier transforming means 103 by the sides of the polygon and put together with the output of an internal phase compensation item generating means by a selected Fourier transformation composing means 104 to generate the multibeam by a multibeam generating means 6. The Fourier transformation processes are performed in parallel to shorten the signal processing time for the multibeam generation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a holographic radar antenna device that forms multiple beams.

[Conventional technology]

Conventional antenna devices of this type include 9, for example, Japanese Unexamined Patent Publication No. 1-3
There is one shown in Publication No. 11704. FIG. 1 is a block diagram of main parts of a conventional antenna device.

(1) is an element antenna, (2) is a receiving means connected to each element antenna, (3) is a buffer circuit, and (4) is a computer that performs signal processing to form a multi-beam.

Next, an outline of the operation will be explained.

Electrons reflected at the target are received by element antennas (11) arranged circularly in a constant periodic arrangement, and the high-frequency signal is converted into a digital complex video signal by receiving means (2) connected to each element antenna. The output of the receiving means is inputted to a computer (4) via a buffer circuit (3), and subjected to signal processing to form a Yaruchi beam.

4. When multiple radio waves arrive at the antenna device at the same time.
Each direction simultaneously forms the main beam.

can be received at the same time.

In the above receiving means (2), as shown in FIG. 10, the high frequency signal input from the element antenna (1) is input to the mixer (5) and the product of the output of one local oscillator (11) is and converted to an intermediate frequency signal. Mixer (5
The output of The product of the output signal of the coherent oscillator (8) and the signal whose phase is delayed by 90° by a 90° phase shifter (91) is taken, and each phase is detected.The output of each phase detector is received. The real part (Li) and imaginary part (Q, ) of the complex video signal are converted into a digital complex video signal by the MU/D converter aO.

The computer (41) performs signal processing according to the flowchart shown in FIG. 11 to form a multi-beam.

In step +11, the received signal Sr is subjected to 7-lier transform xp
't- seek. As shown in FIG. 9, when N element antennas are arranged circularly in a constant periodic arrangement, when a radio wave of wavelength λ arrives from the angle φ direction, the r-th element antenna is assumed to be omnidirectional. The received signal Sr received by the element antenna can be expressed by the following equation.

Sr枦)+espr(-j2xa/λ) als (φ
-rΔθ)) il+where, a: Angle that adds the element spacing on the circumference of a circle with a radius of 201 r: Number of the element antenna (""0.1+..., N-1
) If the above received signal s r gloss ) is Fourier transformed and is expressed as Xp, it can be expressed by a 9th order equation.

! p=F (8r gloss) 1 121
Here, F: In the Fourier transform step (2), the weight Tr is Fourier transformed to obtain Yp. The weight Tr to be multiplied by the received signal of the r-th element antenna in the first equation can be expressed by the following equation.

Tr=Wr−eHp[(−J2ffa/λ) cas
(rΔθ−(M−1)Δθ/2))
1al(r=o, 1.・+M
-1) Tr=O(41 (r == M, M+1, ., N-1) where, Wr: Window function M; Number of element antennas contributing to beam formation If the above weight Trf Fourier transform is Yp .

It can be expressed by the following formula.

Yp=FrT-r) 5 15
) In step (3), the product zp of the lid p and Yp is determined. From the second equation and the fifth equation, the product Zp can be expressed by the following equation.

Zp=Xp-Yp=FC5r(1)) ・IF CT-r118+step (In 41, the above product zp is inversely transformed into an inverse 7-lier transform to obtain the antenna radiation pattern Ikl. The antenna radiation pattern Ek can be expressed by the following equation.

Ek flight) = 7 (Zpl
(7) Here? −1; By inverse Fourier transform or above], the antenna radiation pattern Bk(φ) of N multi-beams, (heat = 0.1...t") can be obtained simultaneously. [Issues to be solved] Conventional antenna devices of this type have one or more configurations, and require a large amount of signal processing calculations to form multi-beams by a computer in order to simultaneously receive multiple incoming radio waves. The problem was that it required a lot of processing time.

The present invention was developed to solve the above-mentioned problems, and an object of the present invention is to obtain an antenna device that can shorten the signal processing time for forming multi-beams.

[Means to solve the problem]

In order to achieve the above object, the antenna device of the present invention is an array antenna in which each element antenna is arranged in a polygonal manner in a constant periodic arrangement, and processes the output signal of each element antenna to generate a complex signal. A receiving means for obtaining a signal, a plurality of Fourier transform means for performing Fourier transform on each side of each of the complex signal full polygons, and a synthesizing means for selecting and synthesizing the outputs of the Fourier transform means. It is characterized by

[Effect]

Configured as above. In the array antenna system, each element antenna includes a receiving means for processing its output signal to obtain a complex signal, a plurality of Fourier transform means for Fourier transforming each of the complex signals for each side of a polygon, and Since the plurality of Fourier transform means perform parallel calculations, the signal processing time for forming a multi-beam can be shortened.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to Example f: Cause.

FIG. 1 is a block diagram of the main parts of the antenna device of the present invention. Element antenna (1
1. Receiving means (21 has already been explained, so
The explanation will be omitted here.

In Fig. 1, (11 is MXB element antennas arranged circumferentially in a constant periodic arrangement on the side surface of a polygonal prism (105) (5=8 in this case), (2) is for each element antenna, respectively. A plurality of Fourier transform means performs Fourier transform on the outputs of the connected receiving means, (105) is the receiving means for each polygon, and (104) performs a sum-of-products operation on the output of the Fourier transform means and its phase compensation term. (105) is a polygonal prism, (1
06) A multi-beam forming means comprising an Fi Fourier transform means and a combining means.

FIG. 2 is a block diagram of the synthesizing means (104) in FIG. 1.

In the figure, j (201) is a storage means for storing the outputs of each Fourier transform means (103) shown in FIG. 1 in a two-dimensional grid based on polygon side number e9 and partial beam number m'fI.

(203) is a phase compensation term generation means for the partial beam data read out from the storage means (201), and a phase compensation term generation means (203) for the output of the storage means (201).
203) complex multiplication means for performing complex multiplication with the output of 203).

(205) is a complex multiplication means (complex addition means for complex addition of 20 outputs, and (206) is a product-sum calculation means comprising a complex multiplication means and a complex addition means.

The formation of partial beams will be explained with reference to FIG.

Figure 3 corresponds to one side, which is the basis of a polygon.
The direction t in which side & CM element antennas (1) are lined up in a straight line!
- The X-axis and the front direction of the element antenna perpendicular to the Y-axis, it is possible to simultaneously form a partial beam y* having r St- of the arrival direction of the radio wave and the Y-axis.

In addition, the output S of the receiving means connected to each element antenna
m has a weight coefficient for sidelobe suppression, where r=-
M/2. (-M/2)+1. ... Oo... (M
/2) 1 FIG. 4 is a diagram showing the directivity Jt4+ of the partial beam and the total beam. Here, the horizontal axis is the azimuth angle φ, and the -axis is the gain B.
f: Represent. As defined in FIG. 5, the azimuth angle φ represents the angle from the reference axis (401) of the polygon, e represents the side number of the polygon, and the side opposite to the reference axis (401) is 8=1
and the maximum value S of 8 is equal to the number of polygon dimensions. Figure 4 (a), (b), (C), and (d) show polygon side numbers θ=1.2, 3. ...For each side of S.

FIGS. 4(8) and 6 show the directivity of the partial beams (601) formed by M element antennas, respectively, and FIGS. - Shows examples.

In addition, as shown by diagonal lines in Figure 5, the area partitioned by one side of the polygon and the extension of the straight line connecting the vertices at both ends and the center 0 of the polygon is 1 of the above polygon. This shows the main observation area of the element antennas placed on the sides.Next, we will explain the formation of the overall beam.・Now.

Consider the formation of a total beam in the direction of polygon side number day 1 partial beam number m. The main beam direction φ of the above-mentioned total beam can be expressed by Equation 10.

φ(e, m) 1l = (θ-1) ・2x/B+C(m 1 )-(M/
2) :] ・Δθ Here, θ: Side number S of the polygon; Number of sides of the polygon (=maximum value of side numbers) m; Partial beam number of each side of the polygon Synthesizing means (104 ) storage means (201
) K stores data of partial beam forming results.

Now, if the azimuth angle of the overall beam in the desired direction is φ, and the serial number t-a of the polygon that includes that direction in the main observation area, then 1 additional number a, (θ-1), (8+1) part 6w −
The data in the direction φ is read out from the storage means (201). Then, the total bee input/output ratio is determined by the sum-of-products operation of the combining means.

The above-mentioned total beam output Bφ can be expressed by Equation 11.

4= al ・b1+a2 ・'b2+a51.
' (111 here + al m a2 +
"5 is the phase compensation term for each of the partial beam outputs in the same two directions that form the total beam, and 5i112 formula? Table 1.
Z. bI L '2 @b3 The above partial beam output read from the storage means (201) in order to form the '-frame can be represented by the corresponding one.

-1 poison (-2jπha/λ) (13 (enemy = 1.2.
3) Here, h day is the distance from the phase reference point on each side of the polygon to the wavefront of the incoming radio wave passing through the center point of the polygon, and the 13th
It can be expressed as a formula.

h6 = ras (φ-(81) 2π/S)
Q:1□' A geometrical explanation of Equation 13 will be given below with reference to FIG. In Figure 1, O is the center point of the polygon (105), A, B, and c are the centers of each side, and r is the phase reference point of each side, and r is the center point of the polygon (105), and each The distance from the phase reference point of the side, φ indicates the direction of the incoming radio wave, and the wavefront passing through the center point 0 (90 is the plane of equal phase of the incoming radio wave from the φ direction. Now, the serial number e of the polygon =1
．． In order to combine 2e s array antennas to form a comprehensive beam with □ main pinim directivity in the φ direction, the phase reference between the array antennas on each side must be 2
πh 1 /λ, 2πh 2 /λ.

Since the difference is from 2πh 3 /λ, a total beam with a high gain can be formed by adding the 75 partial beam outputs for which phase compensation is performed. This is none other than the Kutori Type 11 mentioned above.

As an example is shown in FIG. 4, polygon serial number 8=:i,
2t The array antenna arranged on three sides is φ=π/
To form a total beam with a directivity of 4, the partial beam output with a directivity of φ=π/4 on each side (Fig.
(a)) Perform phase compensation for the beam shown with diagonal lines in (C)], and calculate the force a to obtain the total beam output → (beam shown with diagonal lines in Fig. 4 (e) and beam shown in Fig. 6) ] can be formed.

FIG. 8 is a flowchart explaining the operation of the multi-beam forming means (IO2) of FIG. 1.

In step (301), the output of the receiving means for each polygon is Fourier transformed.

In step (302), an initial value O is given to the serial number 8 of the polygon.

In step (503), the polygon serial number 8 is incremented.

In step (304), an initial value O is given to the beam number m.

In step (305), the beam number m is incremented.

In step (306), the output of the Fourier transform is synthesized,
Find the total beam in the pointing direction φ.

In step (507), it is determined whether the beam number m has become M. If not, the process returns to step (505) and repeats.

In step (30B), it is determined whether the serial number θ of the polygon has become S, and if not yet.

Return to step (303) and repeat.

By performing the above steps (50) to (508), a total of N=SM multi-beams are formed over the entire circumference of the polygon with an azimuth angle of 2π.

With the above configuration, it is possible to obtain an antenna device that can shorten the signal processing time for forming a multi-beam that simultaneously receives a plurality of incoming radio waves compared to conventional systems.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces an effect that is memorized when moving up and down. It is an array antenna in which each element antenna is arranged in a polygon in a constant periodic arrangement, and includes a receiving means for processing the output signal of each element antenna to obtain a complex signal, and receiving means for obtaining a complex signal by processing the output signal of each element antenna, It is possible to shorten the signal processing time required to select and combine the outputs of the plurality of 7-tier transform means that perform Fourier transform on a side-by-side basis, and the outputs of the Fourier transform means described above.

[Brief explanation of drawings]

FIG. 1 is a block diagram of essential parts of an embodiment of the antenna device of the present invention, and FIG. 2 is a block diagram of the combining means of FIG. 1. Figure 3 is a diagram explaining the original hearing of partial beam creation, Figure 4 is a directional characteristic diagram of the partial beam and total beam, and Figure S is the azimuth angle, polygon side number, and the element antenna receiving on one side. A diagram showing the definition of the main observation area. *s'a is a diagram showing an example of the total beam, Figure 1 is a diagram showing the definition of variables of the phase compensation term for total beam formation, and Figure 8 explains the operation of the multi-beam forming means in Figure 1. Fig. 10 is a block diagram of the receiving means of Fig. 9, and Fig. 11 is a flowchart of multi-beam forming of the computer shown in Fig. 9. be. In the figure, (11 is an element antenna* (211d receiving means, (103) is a Fourier transform means, (104)
is a composition means* (1os> is a polygonal prism, (106)
d multi-beam forming means; (201) storage means;
(203) is a phase compensation term generation means, (204) is a complex multiplication means, (205) is a complex adder means, (
206) is a product-sum calculation means. In Figure 9, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] An array antenna in which each element antenna is arranged in a polygon with a constant periodic arrangement, and a receiving means for processing the output signal of each element antenna to obtain a complex signal, and receiving means for obtaining a complex signal by processing the output signal of each element antenna, An antenna device comprising: a plurality of Fourier transform means that perform Fourier transform on a side-by-side basis; and a synthesis means that selects and synthesizes the outputs of the Fourier transform means.