JPS62203403A - Feeding circuit for array antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention provides an antenna arrangement in which a plurality of subarrays each formed of a plurality of antenna elements are distributed on an arbitrary antenna arrangement plane so as to correspond to a plurality of beam directions, respectively. The present invention relates to a feeding circuit for an array antenna, which is arranged in such a manner that the sub-arrays are arranged in such a manner as to selectively feed power to these sub-arrays in order to realize a desired beam direction.

(Prior Art and its Problems) Mobile satellite communication for mobile objects such as ships and aircraft requires a satellite tracking function that directs the beam of a mobile antenna to the satellite according to the position of the satellite. Currently, marine antennas use a method that mechanically directs the antenna itself toward the satellite, but electronic beam scanning antennas with no moving parts, which are expected to be lighter and smaller, are the future choice for array antennas for mobile objects. It is promising as

An electron beam scanning array antenna is an array antenna that directs a beam in a desired direction by controlling the excitation amplitude and phase of each element antenna arranged on an arbitrary surface. Regarding the arrangement of element antennas and the shape of the surfaces on which they are arranged, various arrangements have been proposed depending on the application conditions of the antennas. For example, as mobile antennas that require a hemispherical or larger scanning range, there are array antennas arranged on a spherical surface (spherical array antenna), antennas that combine a plurality of array antennas, and the like.

Figures 1 and 2 show conventional examples of this type. Figure 1 shows element antennas 1 arranged on a spherical surface 2, and Figure 2 shows nine element antennas 1 arranged on a plane. This is a combination of two planar array antennas.

The beam scanning method for this type of array antenna is (
1) A method in which the beam direction is always changed using all element antennas 1, (2) A method in which the element antenna 1 is divided into multiple blocks (subarrays), each subarray constitutes one fixed beam, and these beams are A method of switching according to the desired pointing direction, (3) Method (1) and Method (2)
), that is, a method of scanning the beam direction of each subarray and switching the beams.

Among these methods, the fil method excites all element antennas, which makes its control complicated, and when beam scanning is performed over a wide angular range, there is a possibility that high-level side lobes may occur. . For this reason, it is considered unsuitable for mobile satellite communication, which requires small size and light weight and a wide satellite tracking range.

In the following, the present invention is directed to an array antenna that performs beam scanning using the method (2) or (3) above, and a feeder circuit used therein will be described.

Further, as the element antenna 1, there are a microstrip antenna, a cross dipole antenna, etc., but since the type of element antenna does not matter, a detailed explanation thereof will be omitted.

FIG. 3 shows an example of the configuration of a receiving system power supply circuit in the method (2) above. In the figure, 3 is a low noise amplifier, 4 is a KXM switch matrix, 5 is a variable phase shifter, 6 is a variable attenuator, 7 is a combiner, K is the total number of element antennas, and M is the number of elements in the subarray. This is the maximum value. The waves incident on each element antenna are amplified by a low noise amplifier 3 and then input to a KXM switch matrix 4. The K×M switch matrix 4 outputs only the signals added from the element antennas belonging to the desired subarray, and each output signal is sent to the variable phase shifter 5. and variable attenuator 6
A predetermined phase amount and attenuation amount are added respectively by
The synthesizer 7 synthesizes the signals. Note that C is a control signal for controlling the switch matrix 4, which determines the pointing direction of the antenna in advance from the position of the communication satellite, the position of the moving object, the attitude of the array antenna, etc., and selects the sub-array to be used based on the pointing direction. Select the element antenna belonging to .

FIG. 4 shows another configuration example, which includes an element antenna 1, a low noise amplifier 3, a switch 8, a variable phase shifter 5, and a variable attenuator 6.
A desired number of element antennas 1 are provided, and a desired element antenna 1 is selected by a switch 8 based on a control signal C.

As is clear from FIGS. 3 and 4, in the configuration example of FIG. 3, the switch matrix has a size corresponding to the number of elements, and in FIG. 4, the same number of variable phase shifters 5 and variable attenuators 6 as the number of elements This requires a fairly complex power supply circuit.

Furthermore, FIG. 5 shows an example of the configuration of the receiving system power supply circuit in method (3). In the figure, 9 is an N;1 switch, and N is the number of subarrays.

As is clear from the figure, also in this configuration example, the number of required phase shifters and attenuators is large, and the power supply circuit is complicated.

(Object of the Invention) The present invention solves the above-mentioned drawbacks in the feeding circuit for a beam scanning array antenna, and provides a feeding circuit for the array antenna having an HjP configuration.

(Structure of the Invention) In order to achieve this object, the feeding circuit for the array antenna of the present invention is arranged so that a plurality of subarrays each formed of a plurality of element antennas correspond to a plurality of beam directions. In a feeding circuit for an array antenna that is distributed on an arrangement surface and selectively feeds power to the subarrays in order to realize a desired beam direction, when configuring any of the subarrays, All the element antennas are divided into a plurality of groups so that only one element antenna at most can be used, and the sub-array is formed by selecting one element antenna from the groups.

The plurality of element antennas constituting each of the plurality of subarrays are small (in each unit area of one type of shape, the positional relationship is the same as the position of the element antenna of the corresponding area of the other subarrays on the unit area). The above-mentioned group can be formed by the element antennas arranged in the positional relationship of - each time.

The present invention will be described in detail below using the drawings.

(Example) FIG. 6 is a configuration example of a power supply circuit according to the present invention based on the above method. In the figure, 10 is a nil switch, where n is the maximum number of element antennas included in each group. As is clear from comparing FIGS. 3 to 5 with FIG. 6, the power supply circuit according to the present invention requires only variable phase shifters 5 and variable attenuators 6, and k is selected as small as possible. As a result, considerable simplification can be expected.

By the way, it is also possible to use an electron beam scanning antenna in which the element antenna 1 is excited with a uniform amplitude without using the variable attenuator 6, which requires complicated control, and only the excitation phase is controlled. For example, in the method (3), beam scanning of the subarray can be performed only by controlling the phase. Furthermore, in method (2), even if the element antennas constituting the subarray are excited with uniform amplitude, there may be no practical problem. moreover,
It is assumed that the required phase amount has a finite number of discrete values, rather than all continuous values within a certain desired range. This means that in method (3), beam scanning is performed by switching between a plurality of beams with different main beam directions of the subarrays, and this is often sufficient in practice.

The configuration of the feed circuit of the electron beam scanning array antenna according to the present invention that controls only the phase amount will be described below.

First, FIG. 7 shows a configuration example of a conventional power supply circuit using a variable phase shifter 5, and has a configuration in which the variable attenuator 6 is removed from the example in FIG.

Next, the type of phase amount required for all element antennas 1 is assumed to be m. Furthermore, as described above, all element antennas are divided into groups. An example of the configuration of the power supply circuit according to the present invention under such conditions is shown in FIG. In the figure, 11 is a kXm switch matrix, and 12 is a fixed phase shifter. The n:1 switch 10 is controlled to be connected only to the element antennas 1 constituting a desired subarray, and at most one received signal from each element antenna group is input to the kpm switch matrix 11. k×
In the m-switch matrix 11, a switch is switched to an output port that gives a desired phase amount to each input signal, and a predetermined phase amount is added to the output signal from each port by a fixed phase shifter 12 connected to that port. and then synthesized.

As is clear from comparing FIG. 7 and FIG. 8, the conventional configuration example requires the KXM switch matrix 4 and the variable phase shifter 5, and the control thereof is also complicated, whereas the present invention In the configuration example, it is realized using a k×m switch matrix 11 and m fixed phase shifters 12, and the power supply circuit can be made into an hour wheel, and only the control of the switch matrix is required. Control becomes unnecessary.

FIG. 8 shows an example of a configuration using a switch matrix 11 that performs processing in the radio frequency (RF) band.
It is difficult to fabricate a switch matrix in the band. Therefore, FIG. 9 shows an example of the configuration of a power supply circuit according to the present invention that processes the intermediate frequency (IF) band. In the figure, 13 is a local oscillator, 14 is a mixer, and 15 is an IF band k.
This is an Xm switch matrix, and the processing other than frequency conversion by the local oscillator 13 and mixer 14 is the same as the configuration example shown in FIG.

A general description has been given above of the feeder circuit for the electron beam scanning array antenna according to the present invention.

Hereinafter, the configuration of the power feeding circuit according to the present invention will be explained in more detail using specific examples.

First, as a first example, an antenna in which M-element planar array antennas that perform beam scanning of method (3) are arranged in N planes will be described. In this case, the number of element antenna groups is M, and the number of element antennas included in each group is N. Therefore, the embodiment of the present invention of the power feeding circuit in this example is as shown in FIG. In the figure, 16
is an M x m switch matrix. Comparing this figure with the conventional configuration example shown in FIG. 5, the conventional configuration example requires MXN variable phase shifters 5 and their control, but in the present invention, It is constructed using a phase box 12 and an M×m switch matrix 16.

Next, as a second example of performing beam scanning in method (2),
Let us take up a spherical array antenna in which 76 element antennas are arranged on a spherical surface. FIG. 11 is a perspective view showing the element arrangement of a 76-element spherical array antenna.

The spherical surface on which the element antenna 1 is arranged is a spherical surface that circumscribes all the trisection points on each side of the regular icosahedron, and the element antenna 1 is arranged evenly from these trisection points and five adjacent trisection points. They are placed at points on the spherical surface that are at a distance, and at points on the spherical surface that are equidistant from the six adjacent trisection points. Furthermore, three types of subarrays are used, which are not shown in FIG. 12: a regular pentagonal type (type 1), a regular hexagonal type (type 2), and a suspect hexagonal type (type 3). Furthermore, in the spherical array antenna, since the element antennas 1 are not on a plane, it is necessary to align the planes of polarization of each element antenna 1.

In order to align the plane of polarization in every subarray,
This is not possible by adjusting the physical arrangement, and requires phase adjustment of each element antenna 1. Figure 13 shows the arrangement position (O) of the element antenna l at the coordinates (θ, φ) shown in Figure 11.
This figure shows an example of the reference polarization plane (=O). Assuming that the type of phase amount required to align the polarization planes for all subarrays is m, in this example, m = 19
becomes. Furthermore, the minimum k that satisfies the grouping conditions is 8, and the element antenna l included in each group
The number will be 9 or 10.

Therefore, the embodiment of the power feeding circuit of the present invention in this example is shown in FIG. In the figure, 17 is a 10:l switch,
18 is an 8×19 switch matrix.

Comparing the configuration example in this figure with the conventional configuration example in FIG. 7, the latter configuration requires 76 variable phase shifters 5, whereas the configuration of the present invention requires an 8 This can be realized by using the power supply circuit 18 and 19 fixed phase shifters 12, and the configuration of the power supply circuit is extremely simple, and the control is also simple.

(Effects of the Invention) As described above in detail, the present invention greatly reduces the number of required phase shifters and attenuators by grouping the element antennas as described above, and When an attenuator is not used, a small-scale switch matrix and a fixed phase shifter are used to provide a feeding circuit for an array antenna that has a simple configuration and is easy to control. Although the above explanation was only about the receiving system power supply circuit, a similar configuration can be obtained for the transmission system power supply circuit by replacing the low noise amplifier 3 with a high power amplifier and the combiner 7 with a distributor. It will be done.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing an example of a spherical array antenna, Fig. 2 is a schematic perspective view showing an example of an array antenna combining 9-element planar array antennas, and Fig. 3 is a case where beam scanning of method (2) is performed. FIG. 4 is a block diagram showing another example of the configuration of the feed circuit when performing beam scanning in method (2), and FIG. FIG. 6 is a block diagram showing an example of the configuration of a power feeding circuit according to the present invention, and FIG. 7 is a block diagram showing an example of the configuration of a conventional power feeding circuit that does not use an attenuator. , FIG. 8 is a block diagram showing a configuration example of a power supply circuit according to the present invention without using an attenuator, FIG. 9 is a block diagram showing a configuration example of a power supply circuit according to the present invention using an IF band switch matrix, and FIG. 10 is method (3
), FIG. 11 is a perspective view of a 76-element spherical array antenna, FIG. 12 is a perspective view showing an example of the configuration of a sub-array, and FIG. 14 is a diagram showing the arrangement of element antennas and a reference plane of polarization, and FIG. 14 is a block diagram showing an embodiment of a feeding circuit according to the present invention when a 76-element spherical array antenna is used. I... Element antenna, 2... Spherical surface, 3... Low noise amplifier, 4... KXM switch matrix,
5... Variable phase shifter, 6... Variable attenuator, 7...
・Synthesizer, 8...switch, 9...N:1 switch, 10...nil switch, 11...kXm
Switch matrix, 12...Fixed phase shifter, 1
3...Local oscillator, 14...Mixer, 15.
...IF band kXm switch matrix, 16...
Mxm switch matrix, 18...8x19 switch matrix.

Claims (1)

[Claims] A plurality of subarrays, each formed by a plurality of element antennas, are distributed and arranged on an arbitrary antenna arrangement surface so as to correspond to a plurality of beam directions, respectively, and the subarrays are selected to realize a desired beam direction. In a power feeding circuit for an array antenna, all element antennas are divided into a plurality of groups so that only one element antenna from each group can be used at most when configuring any of the above sub-arrays. A feeding circuit for an array antenna, characterized in that the sub-array is formed by selecting one of the element antennas.