JPH07122930A - Circular polarized wave planar antenna - Google Patents

Abstract

PURPOSE:To turn frequency characteristics to a wide band and to widen an angle by turning a dielectric plate to a three dimensional curved surface shape and performing constitution radially from a center with a specific interval while specifying respective power feeding phase differences. CONSTITUTION:With the vertex D of the dielectric plate 3 as the center, four radiation microstrip patch elements 1a-1d are rotated respectively for 90 deg. to be arranged and provided along the curvature of the upper surface of the dielectric plate 3. Further, power feeding points (a)-(d) are arranged at positions counterclockwisely rotated respectively for 90 deg. in point symmetry with the vertex 0 of the curved surface as the center. By synthesizing the four pieces of the output in the microstrip lines 4a-4d, 5a and 5b for power feeding of a prescribed line.Length, the respective phase difference of 0 deg., 90 deg., 180 deg. and 270 deg. are provided in the power feeding. Thus, at the output point P of the microstrip lines 4a-4d, 5a and 5b for power feeding, complete circular polarized waves are generated by synthesizing four elliptical polarized waves in different directions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circular polarization plane antenna having a wide angle circular polarization characteristic (axial ratio) and a wide frequency bandwidth of the circular polarization characteristic (axial ratio).

[0002]

2. Description of the Related Art FIG.
5 is a plan view of a circularly polarized plane antenna (microstrip antenna) proposed in Japanese Patent Publication No. 5 (hereinafter referred to as a first conventional example), and FIG. 4B is a sectional view thereof. Further, FIG. 5A is a plan view of a circularly polarized microstrip antenna (hereinafter referred to as a second conventional example) disclosed in Japanese Patent Laid-Open No. 3-80703, and FIG. 5B is a cross section thereof. The figure is shown.

The first conventional example and the second conventional example are
The radiation conductors 7 and 11 are arranged on the convex surfaces of the dielectric plates 8 and 12 which are respectively formed in the shape of a curved surface, and the widening of the directional characteristics is intended.

Further, FIG. 6A shows a flat dielectric plate 16
Four "linear" polarized radiation elements 15a, 15b, 15 on top
Circularly polarized radio waves are radiated by arranging c and 15d in a rectangular shape and connecting a microstrip line for power supply to each radiating element to sequentially supply a high frequency current with a phase difference of 90 °. FIG. 7B is a plan view of the microstrip antenna (hereinafter referred to as a third conventional example), and FIG. 6B is a sectional view thereof.

[0005]

The above-mentioned first and second conventional examples are each intended to widen the directional characteristics, and as described below, the circular polarization characteristics ( Axial ratio)
Is narrow, the third conventional example has a narrow frequency bandwidth with respect to the circular polarization characteristic (axial ratio), and the range in which the circular polarization characteristic (axial ratio) can be maintained is narrow. There was a problem.

That is, in the case of the first and second conventional examples,
Low elevation angle (for example, when the horizontal elevation angle is 0 degrees) 1
Frequency-circular polarization characteristics (axial ratio) of the antenna at 5 degrees
As shown in FIG. 3, accurate circular polarization is generated only when the reception frequency is the resonance frequency f0 of the antenna,
When the reception frequency deviates from f0, elliptically polarized waves are gradually combined.

For example, when radio waves from a communication satellite orbiting a low earth orbit are received using this antenna, the circular polarization characteristic (axial ratio) is increased as the frequency of the radio wave from the satellite deviates from the resonance frequency f0 of the antenna. Since it deteriorates, there is a problem that instead of the direct wave (main polarization) from the satellite, the reflected wave (cross polarization) reflected from an obstacle such as a building is received. This is due to the deterioration of the cross polarization discrimination due to the deterioration of the circular polarization characteristics (axial ratio).

In the third conventional example, the two linearly polarized radiation elements 15a and 15b are arranged so as to be physically orthogonal to each other, and the feeding phase difference provided between these two elements is 90 °. The power is supplied so that a circularly polarized radio wave is generated. That is, two linearly polarized radiating elements are paired (called the first pair).
By doing so, circularly polarized waves are obtained.

The second pair of linearly polarized radiating elements 15c and 15d also generate circularly polarized waves in the same manner as the first pair, and the circularly polarized waves of these two pairs are combined to obtain an accurate result. It was designed to synthesize circularly polarized waves. However, also in this case, as in the first and second conventional examples, a microstrip line (line length l = λg / 4) having quarter wavelength intervals such that the feeding phase difference is 90 ° is provided. Frequency f0 (resonance frequency) f0 = (3 * 10 ^ 8) * η / λg Here, when λg = line wavelength and η = wavelength reduction ratio, an accurate circular polarization is generated, and when the frequency deviates from f0, Elliptical polarization will be synthesized.

Therefore, also in this case, similarly to the first and second conventional examples, there is a problem that the frequency bandwidth of the circular polarization characteristic (axial ratio) becomes narrow. Further, as shown in the cross-sectional view of FIG. 6B, the radiation element is provided on the flat dielectric plate, so that the circular polarization characteristic (axial ratio) in the horizontal direction of the figure is deteriorated. That is, there is a problem that the range of angles that can maintain the circular polarization characteristics is a narrow angle.

As described above, the conventional circularly polarized plane antenna has a narrow frequency band with respect to the circularly polarized wave characteristic (axial ratio) and has an angular range in which the circularly polarized wave characteristic can be maintained. There was the problem of having the drawback of being a narrow angle.

Therefore, the present invention has been made in view of the above problems in the prior art. The frequency characteristic of the circular polarization characteristic (axial ratio) of the antenna is widened and the circular polarization characteristic (axial ratio) is increased. It is an object of the present invention to provide a circularly polarized plane antenna in which the angle that can maintain the above) is widened.

[0013]

In order to achieve the above-mentioned object, a circularly polarized plane antenna according to the present invention sandwiches a dielectric plate and has four circularly polarized radiation microstrip patch elements on one surface. A circular polarization plane antenna in which a grounding conductor plate is provided on the other surface facing each other, wherein the dielectric plate has a three-dimensional curved surface shape, and the four circular polarization radiation microstrip patch elements are the three-dimensional shape. 0 from the center of the curved surface
It is characterized in that the power feeding phase difference is 0 degree, 90 degrees, 180 degrees, and 270 degrees at intervals of 90 degrees, 90 degrees, 180 degrees, and 270 degrees.

Further, in the circularly polarized plane antenna according to the present invention, in order to achieve the above-mentioned object, the center of the three-dimensional curved surface is its apex, and the four circularly polarized radiation microstrip patch elements have the apexes. The feature is that they are symmetrically arranged in the center.

More specifically, in order to achieve the above-mentioned object, the circularly polarized plane antenna according to the present invention has a shape of a dielectric plate having a three-dimensional curved surface, and gold, silver, copper, or both surfaces of the dielectric plate. A conductor plate (or conductor layer) made of aluminum or the like is laminated by thermocompression bonding or an adhesive agent, and further four circularly polarized radiation microstrip patches centering on the apex of the curved surface by etching means or the like on the surface thereof. The element is arranged at a position rotated by 90 ° in points, and a ground conductor plate is provided on the entire back surface.
In addition, a power supply microstrip line for each circularly polarized radiation microstrip patch element is provided on the same plane as the circularly polarized radiation microstrip patch element, and the length of each line is lengthened by a quarter wavelength. By 90
It is characterized in that it is configured such that a phase difference is provided for each degree, and the combined output is taken out from the ground conductor plate side via a coaxial line.

[0016]

Since the circularly polarized planar antenna according to the present invention is configured as described above, the reception frequencies of the four circularly polarized radiation microstrip patch elements (hereinafter referred to as "radiating elements") are the resonance frequencies of the antenna. When each radiating element radiates an elliptically polarized wave outside f0, it operates as described below. That is, the elliptically polarized wave generated from the first radiating element 1a and the elliptically polarized wave generated from the second radiating element 1b are generated from a position physically rotated 90 degrees counterclockwise, and The radiating element 1b has a first feeding phase
Is delayed by 90 degrees with respect to the feeding phase of the radiating element 1a of
Since the length of the feeding microstrip line is shifted by a quarter wavelength [(b to e)-(a to e) = λg / 4], the two elliptical polarized waves are combined into a complete circular polarization. Waves are generated.

The physical arrangement of the first radiating element 1a is set to 0.
9 times the second radiating element 1b with respect to the first radiating element 1a.
The third radiating element 1c is arranged at 180 degrees with respect to the first radiating element 1a, and the fourth radiating element 1d is arranged at 270 degrees with respect to the first radiating element 1a. Elliptical polarization generated from the radiating element 1b and the third radiating element 1c
The elliptically polarized wave generated from is located at a position physically rotated counterclockwise by 90 degrees, and the feeding phase of the third radiating element 1c is delayed by 90 degrees with respect to the feeding phase of the second radiating element 1b. . Therefore, perfect circular polarization is generated by combining these second, third, and elliptical polarizations.

Similarly, perfect circular polarization is generated by combining the third, fourth, and second elliptical polarizations, and perfect circular polarization is also generated by combining the fourth, first, and second elliptical polarizations. Occur.
As a result, at the output point P of the feeding microstrip line, perfect circular polarization occurs due to the combination of elliptical polarizations having different directions. Therefore, the frequency bandwidth capable of receiving circularly polarized waves is greatly expanded.

In addition, since the radiation microstrip patch element is provided on the three-dimensional curved dielectric plate, the field of view in the lateral direction of the radiation microstrip patch element is improved, so that the circular polarization characteristic in the horizontal direction ( The axial ratio is widened, and the frequency band width of the circular polarization characteristic (axial ratio) is widened in a wide angular range.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1A is a plan view of a circularly polarized planar antenna (microstrip antenna) according to an embodiment of the present invention, and FIG. 1B is a side view thereof.
2 is a sectional view thereof. In FIG. 1, 1a, 1
b, 1c and 1d are radiation microstrip patch elements for circularly polarized radiation, 2 is a ground conductor plate, and 3 is a dielectric plate. Reference numerals 4a, 4b, 4c, 4d, 5a and 5b are microstrip lines for feeding, and 6 is a coaxial line for feeding.

In this embodiment, the dielectric plate 3 is the same as that shown in FIG.
As shown in the cross-sectional view of FIG. 3, the cross-section is composed of a portion above the straight line A′-B ′ parallel to the major axis AB of the ellipse, and with the vertex D of the dielectric plate 3 as the center, Four radiating microstrip patch elements 1a, 1b, 1c and 1d are provided by rotating 90 ° each along the curvature of the upper surface of the dielectric plate. The ground conductor plate 2 is provided along the curvature of the lower surface of the dielectric plate 3, and the radiating elements 1a, 1b, 1
Microstrip line 4 for feeding on the same plane as c and 1d
a, 4b, 4c, 4d, 5a, and 5b are provided, and power is fed from a power feeding point P, which is a power feeding composite point, through an output power feeding coaxial line 6 provided on the ground conductor plate 2 side.

In such a structure, four feeding points a, b, c, of the four radiating microstrip patch elements are provided.
microstrip lines 4a, 4 for feeding each connecting d,
The line lengths of b, 4c, 4d, 5a and 5b are set as follows.

4a = (a to e) 4b = (b to e) = 4a + (λg / 4) 4c = (c to f) = (a to e) 4d = (d to f) = 4c + (λg / 4 ) 5a = (e to p) = 5b- (λg / 2) 5b = (f to p) where (λ
g = line wavelength)

The feeding points a, b, c and d are arranged at positions rotated by 90 ° counterclockwise about a point D of the curved surface as a point object. These four outputs have the line lengths set as described above and are used for feeding microstrip lines (4a, 4
b, 4c, 4d, 5a, 5b), the respective feedings have a phase difference of 0 °, 90 °, 180 ° and 270 °.

With this structure, at the output point P of the feeding microstrip line, perfect circular polarization is generated by combining four elliptical polarizations having different directions. Therefore, the frequency bandwidth capable of receiving circularly polarized waves is greatly expanded.

Further, since the radiating microstrip patch element is provided on the three-dimensional curved dielectric plate, the field of view in the lateral direction of the radiating microstrip patch element is expanded, so that the circular polarization characteristic (axial ratio) is improved. A wide angle has been achieved, and the frequency band width of the circular polarization characteristic (axial ratio) in the wide angle range has been widened.

FIG. 3 shows a circular polarization characteristic (axial ratio) -frequency characteristic (solid line) of the antenna according to the present invention shown in FIG.
FIG. 7 is a diagram showing a circular polarization characteristic (axial ratio) -frequency characteristic (dotted line) of the antenna of the conventional example shown in FIG. For example, axial ratio 1
Comparing at the level of dB, in the conventional example, only a bandwidth of less than ± 1% can be obtained, whereas in the present example,
It can be seen that a bandwidth of ± 2.5% or more can be obtained.

[0028]

As is apparent from the above description, the present invention makes the shape of the dielectric plate a three-dimensional curved surface, and provides four circularly polarized radiation microstrip patch elements along the curved surface. , Each of which is rotated radially by 90 °,
The circular polarization characteristics of the antennas were set by setting the phase difference of the four antenna outputs to 0 ° 90 ° 180 ° 270 ° in the feeding microstrip line and combining them. Along with widening the frequency bandwidth of the axial ratio), the range of widening the frequency bandwidth of the circular polarization characteristic (axial ratio) can be widened to greatly improve the performance of the circular polarization planar antenna. did it.

[Brief description of drawings]

1A is a plan view of a circularly polarized plane antenna according to an embodiment of the present invention, and FIG. 1B is a side view of a circularly polarized plane antenna according to the embodiment.

FIG. 2 is a sectional view of a circularly polarized planar antenna according to the embodiment shown in FIG.

[Fig. 3] Circular polarization characteristic (axial ratio) -frequency characteristic diagram of the antenna

FIG. 4A is a plan view of a first conventional example, and FIG. 4B is a sectional view of the same conventional example.

FIG. 5A is a plan view of a second conventional example, and FIG. 5B is a sectional view of the same conventional example.

FIG. 6A is a plan view of a third conventional example, and FIG. 6B is a sectional view of the same conventional example.

[Explanation of symbols]

1a, 1b, 1c, 1d Radiation microstrip patch element 2 Ground conductor plate 3 Dielectric plates 4a, 4b, 4c, 4d, Microstrip line for feeding 5a, 5b Microstrip line for feeding 6 Coaxial line for feeding 7, 11 Radiation Microstrip patch element 8,12 Dielectric plate 9,13 Grounding conductor plate 10,14 Feeding coaxial line 15a, 15b, 15c, 15d Linearly polarized radiation element 16 Flat dielectric plate 17 Feeding microstrip line 18 Grounding conductor Plate a, b, c, d Feeding point of each antenna e, f Branching point p Feeding point D Vertex

Claims (2)

[Claims] 1. A circularly polarized plane antenna in which four circularly polarized radiation microstrip patch elements are arranged on one side of a dielectric plate and a grounding conductor plate is provided on the other opposite side. The dielectric plate has a three-dimensional curved surface shape, and the four circularly polarized radiation microstrip patch elements are 0 °, 90 °, 180 °, and 270 radially from the center of the three-dimensional curved surface.
And the feeding phase difference of each is 0 degree, 90 degrees.
A circularly polarized plane antenna characterized in that the angle is 180 degrees and 270 degrees. 2. The center of the three-dimensional curved surface is its apex, and the four circularly polarized radiation microstrip patch elements are symmetrically arranged about the apex.
The circularly polarized plane antenna described.