JPS6022844B2 - array antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an array antenna in which many element antennas are arranged, each element antenna having the same excitation amplitude, and the radiation pattern of the array antenna being a low side lobe. It is related to.

Conventional array antennas of this type have a plurality of element antennas arranged in a linear or circular shape, and by weighting the excitation amplitude of each element antenna, the excitation amplitude distribution of the entire array antenna can be adjusted to, for example, the Dolph-Chebyshev distribution or the Taylor distribution. We have achieved a low sidelobe radiation pattern by creating a low sidelobe amplitude distribution such as .

For this reason, it is necessary to construct a feeding circuit system with unequal distribution in order to give a desired excitation amplitude to each element antenna, which has the disadvantage that its design and manufacture are complicated and the cost is high. When arranging many element antennas like an array antenna, it is important to efficiently distribute and supply power to each element antenna from the viewpoint of electrical performance and arrangement structure. It can be said that it is better if the circuit configuration is as simple as possible. FIG. 1 is an explanatory diagram of a conventional array antenna, in which a plurality of element antennas 1 are arranged so that their outer periphery is substantially circular along a circumference 2, forming an array antenna 3.

Therefore, if the excitation amplitude of each element antenna 1 is uniform, the side lobe level will be approximately 17 dB, which is almost the same as that of a circular Sekiguchi antenna.In order to further reduce this level, the excitation amplitude of each element antenna 1 must be weighted. In addition, the excitation amplitude distribution of the entire array antenna 3 must be changed to a low sidelobe distribution. In order to eliminate the drawbacks of the secondary structure, this invention distributes power uniformly to each element antenna to simplify the distribution circuit, and at the same time adjusts the outer circumferential arrangement shape of the multiple element antennas to a low sidelobe amplitude distribution shape. This makes it possible to reduce side lobes, and the drawings will be described in detail below.

FIG. 2 shows an embodiment of the present invention, in which a plurality of element antennas 1 are arranged so that their outer circumferential arrangement shape approximately corresponds to a so-called Taylor distribution 4, forming an array antenna 5.

Power is distributed so that each element antenna 1 is excited with the same amplitude. Note that 6 is the basic array mouse. With this configuration, the effect is that the side lobes of the radiation pattern in the plane containing the basic arrangement axis 6 have a low radiation level determined by the Taylor distribution 4 described above. This means that the amplitude of one element antenna of an equivalent linear array antenna projected onto the basic arrangement axis 6 is equal to the number of element antennas arranged in the direction orthogonal to the basic arrangement axis 6 in FIG. This is because it is equal to the proportional amplitude and therefore approximately equal to the amplitude distribution 4 of its equivalent linear array antenna. Moreover, in Fig. 2, each element antenna 1
Since the distribution of the power supplied to the terminals is uniform, the configuration of the distribution circuit is much simpler than that in the case of unequal distribution. In other words, the present invention provides an array antenna whose distribution circuit is easy to design and manufacture, whose cost is low, and whose desired electrical performance is easily obtained. FIG. 3 shows another embodiment of the present invention, but in this case, the outer circumference array shape line 7 of the element antenna 1 does not match the Taylor distribution 4 as shown in FIG. However, the element antennas 1 are arranged in a direction orthogonal to the basic arrangement axis 8 so that the amplitude distribution of the equivalent linear array antenna projected onto the basic arrangement axis 8 becomes a certain desired Taylor distribution. The number of has been selected. In this way, the Taylor distribution is equivalently realized even if the outer circumferential array shape line 7 does not match the Taylor distribution curve itself. In the example shown in FIG. 8, the array antenna 9 as a whole has a substantially symmetrical structure with respect to the basic array axis 8. In addition, also in this example,
Naturally, the excitation amplitude of each element antenna 1 is the same, and the power distribution circuit to the array antenna 9 is an equal distribution circuit. Although the case where the Taylor distribution is used as the low siderope amplitude distribution has been described above, the present invention is not limited to this, and the Dorftebyshev distribution, the cosine (cosine) distribution, etc.
female) distribution, modified Taylor distribution, COSme-on-ped
It can be implemented using any low sidelobe amplitude distribution, such as the esne1 distribution.

Note that, as is clear from the above explanation of the principle, the present invention is limited to the outer peripheral element array shape as in the embodiment, since it is sufficient that the outer peripheral element array shape equivalently matches the shape of the low siderope amplitude distribution. Rather, it can take various shapes in consideration of ease of construction. Furthermore, although we have explained transmission so far, it goes without saying that reception can also be carried out in the same way; It can also be implemented using a so-called phased array antenna that performs scanning. As described above, in the array antenna according to the present invention, by matching the outer circumferential arrangement shape of the arrayed element antennas to the shape of the low sidelobe amplitude distribution, the power distribution circuit configuration can easily achieve uniform distribution and have low sidelobe characteristics. Therefore, when used as a radar antenna, the effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a subordinate array antenna, FIG. 2 is an explanatory diagram of one embodiment of the invention, and FIG. 3 is an explanatory diagram of another embodiment of the invention. In the figure, 1 is an element antenna, 2 is a circumference, and 4 is a Taylor distribution. In the drawings, the same or corresponding parts are denoted by the same reference numerals. Many 1 drawings Many z drawings Many 3 drawings

Claims (1)

[Claims] 1 In an array antenna consisting of a plurality of element antennas arranged at regular intervals in a planar or curved shape, the outer circumferential shape of the array antenna determined by the outer circumferential element arrangement corresponds to the shape of the low sidelobe amplitude distribution. An array antenna characterized by: