JPH04296107A - Planar array antenna - Google Patents

Abstract

PURPOSE:To simplify the constitution of a feeder circuit and to easily form the feeder circuit even when an interval of radiation elements is narrow, in the planar array antenna in which the parallel feeder circuit employing a waveguide is adopted. CONSTITUTION:At least one feeder antenna element 6 and plural radiation elements 1 are arranged opposite to one aperture 2 of a feeding waveguide 3 in the planar array antenna in which the plural radiation elements 1 are arranged in a two-dimension array. Thus, since feed plural radiation elements are fed through one waveguide aperture by one waveguide aperture, the constitution of the waveguide feeder circuit is simplified and even when the interval between the radiation elements is narrow, the parallel waveguide feeder circuit is easily realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat array antenna for receiving satellite broadcasting or satellite communications on the ground.

0002

[Prior Art] In recent years, in planar array antennas used for receiving satellite broadcasting, etc., a configuration in which power is fed by strip lines to each of a plurality of radiating elements arranged in a two-dimensional array is well known. . However, the propagation loss of striplines is generally 1 in the 12 GHz band.
．． The loss is about 5 to 3 dB, and this loss causes a decrease in the gain of the antenna, increases antenna noise, and deteriorates the receiving performance (G/T) of the antenna. In particular, when increasing the size of a planar array antenna, the feed line becomes longer, and the loss of this strip line becomes a major problem that cannot be ignored.

On the other hand, in order to reduce the loss of the feed line in a planar array antenna, a configuration has been proposed in which power is fed in parallel to each radiating element using a waveguide instead of a strip line (Japanese Patent Application No. -134396). In a planar array antenna configured to feed power to each radiating element in parallel using such a waveguide, as the number of radiating elements increases, the configuration of the power feeding circuit using the waveguide becomes complicated. Also,
In order to avoid unnecessary directivity (grating lobes) other than the main directivity direction, when it is necessary to reduce the spacing between the radiating elements to a certain extent, the waveguide is used due to the cut-off frequency. Since there is a lower limit to the diameter, it may become physically impossible to feed power to each radiating element individually.

0004

SUMMARY OF THE INVENTION The present invention simplifies the configuration of the feeding circuit in a planar array antenna that employs a parallel feeding circuit using waveguides as described above, and also enables the antenna to be used even when the spacing between radiating elements is narrow. The purpose is to enable easy configuration of a power supply circuit.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a planar array antenna in which a plurality of radiating elements 1 are arranged in a two-dimensional array as shown in FIG. At least one feeding antenna element 6 is arranged opposite to one opening 2 of the waveguide 3 for
It is characterized in that a plurality of radiating elements 1 are arranged opposite to the feeding antenna element 6 and on the opposite side to the waveguide opening 2.

[0006]

[Operation] The operation of the planar array antenna of the present invention when used for transmission will be explained. The radio waves transmitted by the feeding circuit of the waveguide 3 excite the feeding antenna element 6 from the waveguide opening 2, and this feeding antenna element 6 further excites the plurality of radiating elements 1 above it. and electromagnetic waves are emitted into the air. Here, since a plurality of radiating elements 1 are excited by one waveguide opening 2, the interval between the waveguide openings 2 can be set wider than the interval between the radiating elements 1. This also applies to the case where it is used for reception.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front view of a planar array antenna according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line XX' in FIG. In this embodiment, four feeding antenna elements 6 are excited at one opening 2 of the waveguide feeding circuit shown by the broken line in FIG. Element 1 is excited. In this example, a radiating element 1 consisting of a square patch for receiving two orthogonal linearly polarized waves and a square aperture are used.
A planar array antenna is constituted by a feeding antenna element 6 consisting of a square waveguide feeding circuit for feeding two linearly polarized waves that are also orthogonal to each other. The radiating element 1 can be easily constructed from a metal foil printed on a dielectric film. In addition, in the figure, V is vertical polarization, H
is a horizontally polarized wave, and each radiating element 1 receives a vertically polarized wave V and a horizontally polarized wave H at the same time, and the waveguide opening 2 and L-shaped bend 5
The two polarized waves are propagated independently within the square waveguide 3 through the square waveguide 3.

An antenna module consisting of four power feeding antenna elements and nine radiating elements shown in FIGS. 1 and 2 is considered as one unit, and power is fed in parallel to the four antenna modules using a waveguide circuit. FIG. 3 shows an example in which a 36-element planar array antenna is constructed. For the detailed configuration of the parallel power supply circuit using waveguides used here, please refer to the patent application No.
No. 1-134396. As shown in FIG. 6, this parallel power supply circuit is a power combining circuit composed of a rectangular waveguide, and has a pair of electromagnetic wave input terminals (i.e.
L that converts the propagation direction of the input electromagnetic waves to directions facing each other within the same plane near the waveguide openings A, B or C, D)
a first T-shaped branch P (or Q), each having a type bend, and power-synthesizing the pair of electromagnetic wave inputs propagating in opposite directions in the plane into electromagnetic waves in orthogonal propagation directions in the plane; A pair of waveguide circuits are provided in which the distances from each L-shaped bend to the first T-shaped branch P (or Q) are set to differ by a half wavelength within the waveguide, and each waveguide circuit has a Each waveguide circuit is arranged so that the electromagnetic waves output from the first T-shaped branches P and Q are propagated in opposite directions within the plane, and the electromagnetic waves output from each waveguide circuit are propagated in opposite directions within the plane. It is equipped with a second T-shaped branch R that combines power in propagation directions perpendicular to each other in a plane, and the second T-shaped branch R and the first T-shaped branches P and Q of each waveguide circuit are equidistant. It is located. In such a power supply circuit, the first T-shaped branch P is separated from the center between the end faces a and b of the L-shaped bend by λg/4 (λ
g is the tube wavelength), the first T
It is necessary to set the distance between the type branch P and each L-type bend to be different by λg/2. If one waveguide aperture corresponds to one radiating element, this λg
Although there may be cases where it is not possible to secure the physical space for arranging the antennas in a staggered manner, it is possible to make one waveguide opening correspond to nine radiating elements and four feeding antenna elements, as in the present invention. With this configuration, sufficient physical space can be secured and a parallel power supply circuit using waveguides can be easily realized. By employing such a parallel feed circuit, it is possible to ensure a wider frequency characteristic of the planar array antenna than in the case of employing a series feed circuit. Note that if a partition wall 4 as shown in FIG. 2 is used at the end of one unit of antenna module including nine radiating elements and four feeding antenna elements, interference between the waveguide openings can be avoided. Can be done.

[0009] In the above embodiment, a configuration is disclosed in which nine radiating elements and four feeding antenna elements, which are capable of simultaneously receiving two orthogonal linearly polarized waves, are fed by one square waveguide opening. However, it is also possible to use a configuration in which power is fed using a normal rectangular waveguide using a radiating element and a feeding antenna element that assume reception of only one polarized wave. It is clear that it is also possible to feed individual radiating elements or feeding antenna elements. Furthermore, the waveguide that feeds two polarized waves at the same time is not limited to a square waveguide, but may be a circular waveguide.

Furthermore, in the illustrated embodiment, a feeding element consisting of an aperture (opening) as shown in FIG. 4(a) and a radiating element consisting of a rectangular patch as shown in FIG. 4(e) are used. As the feeding element and the radiating element, Fig. 4(b)
A rectangular annular slot as shown in FIG. 4(c), a circular annular slot as shown in FIG. 4(c), a cross slot as shown in FIG. 4(d), a circular patch as shown in FIG. 4(f), etc.
Various elements can be applied.

Furthermore, by using an element compatible with circularly polarized waves as at least one of the radiating element and the feeding element, a planar array antenna capable of receiving circularly polarized waves can be realized. Here, as the circularly polarized wave element, as shown in FIG. 5, perturbations such as notches and protrusions may be added to the linearly polarized wave element. In FIG. 5(a), a perturbation is added to a rectangular annular slot, and in FIG. 5(b), a perturbation is added to a rectangular patch. Furthermore, by combining this circularly polarized wave element with a waveguide feeding circuit for dual polarized waves, a planar array antenna that can simultaneously receive both left and right polarized waves can be realized. Note that in FIGS. 4 and 5, the hatched portion represents a conductive portion.

0012

[Effects of the Invention] According to the present invention, since a plurality of radiating elements are fed through a single waveguide opening via a feeding antenna element, the configuration of a waveguide feeding circuit can be simplified. This has the effect that a parallel waveguide feeding circuit can be easily realized even when the spacing between the radiating elements is narrow.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of a planar array antenna of the present invention.

FIG. 2 is a cross-sectional view of one embodiment of the planar array antenna of the present invention.

FIG. 3 is a plan view of another embodiment of the planar array antenna of the present invention.

FIG. 4 is a plan view of a radiating element used in the planar array antenna of the present invention.

FIG. 5 is a plan view of a circularly polarized wave radiating element used in the planar array antenna of the present invention.

FIG. 6 is a perspective view of a waveguide circuit used in the planar array antenna of the present invention.

[Explanation of symbols]

1 Radiating element 2 Waveguide opening 3 Waveguide 4 Bulkhead 5 L-shaped bend 6　　　　　　　Power feeding antenna element

Claims (4)

[Claims] 1. In a planar array antenna in which a plurality of radiating elements are arranged in a two-dimensional array, at least one feeding antenna element is arranged opposite to one opening of a feeding waveguide, A planar array antenna characterized in that a plurality of radiating elements are arranged opposite to the power feeding antenna element and on the opposite side of the waveguide opening. 2. A planar array antenna comprising a plurality of planar array antennas according to claim 1, wherein power is fed in parallel to each of the planar array antennas through a waveguide. 3. The planar array antenna according to claim 1, wherein the waveguide is a square waveguide or a circular waveguide capable of simultaneously propagating two orthogonal polarized waves. 4. A claim characterized in that a separation wall is provided between a group of radiating elements fed by one waveguide opening and a group of radiating elements fed by another waveguide opening. 2. The planar array antenna according to 2.