JPH10276038A - Broad angle circularly polarized wave antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize the broad angle cirularly polarized wave antenna while keeping a desired radiation pattern of the antenna used for satellite communication. SOLUTION: This antenna is configured by arranging a helical radiation element 2b that is coupled with the lower side of a grounded conductor plate 4 of a microstrip plane antenna 1 in terms of DC or capacitively to receive feeding almost coaxially under the ground conductor plate 4. A notch 7 is provided to each part of helical radiation elements 2b and a small diameter coil 8 is connected to bridge over the notch 7. Through the constitution above, the antenna 1 is made small without almost giving effect on a radiation pattern of the antenna 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of communications, and more particularly to the miniaturization of a wide-angle circularly polarized antenna effective for portable radio communication using a satellite.

[0002]

2. Description of the Related Art In recent years, various companies have proposed a concept of a mobile phone using a satellite, and the frequency band is 1.6 GHz from a terrestrial mobile phone to a satellite, and from a satellite to a terrestrial mobile phone. Is assigned to the 2.4 GHz band. In the 1.6 GHz band, it is also assigned as a frequency band used for bidirectional communication from the ground to the satellite and from the satellite to the ground. As a circularly polarized antenna applicable to the above-mentioned satellite communication, a wide-angle circularly polarized antenna by the present inventor (Japanese Patent Application No. Hei 8-19638).
No.) has been proposed. This wide-angle circularly polarized antenna electrically connects a helical radiating element below a ground conductor of a microstrip planar antenna. When the microstrip planar antenna and the helical radiating element are arranged substantially coaxially, it is possible to obtain substantially uniform directivity from a low elevation angle to almost all directions from the zenith direction.

[0003]

However, the wide-angle circularly-polarized antenna disclosed in Japanese Patent Application No. 8-19638 reduces the length of the whole antenna while maintaining a desired radiation pattern of the circularly-polarized antenna. Was difficult.

[0004]

According to the present invention, in order to solve the above-mentioned problems, a cut is made in a part of a helical linear radiating element constituting a wide-angle circularly polarized antenna, and small diameters are formed near both ends thereof. A coil is inserted.

[0005] According to the invention, the above-mentioned object is achieved by the means as set forth in the appended claims.

A wide-angle circularly polarized antenna according to the present invention comprises a microstrip planar antenna (hereinafter abbreviated as MSA) and a helical radiating element electrically connected to a ground conductor of the MSA and a small-diameter coil added thereto. Be composed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the structure of the present invention. In FIG. 1c is an MSA dielectric substrate, 2c is a helical portion, 2a is a dielectric support cylinder for supporting the helical antenna, 2b is a helical radiating element, 2c is an intersection at the lower end of the helical antenna. And 2d is an intersection of the radiating elements provided at the lower end of the helical antenna, and 2e is a conductor (edge). Reference numeral 3 denotes a power supply point, 4 denotes a conductor plate serving as a common ground conductor, and 4a denotes a through hole of the conductor plate 4. Reference numeral 6 denotes a signal transmission line such as a coaxial line. The radiating element 2b is DC- or capacitively coupled to the conductor plate 4 through the conductor portion 2e, and is fed through the conductor plate 4. Further, 7 is a cut formed in each of the four radiating elements 2b, and 8 is a small-diameter coil. Small-diameter coils 8 are inserted in the vicinity of each cut 7 and connected to both ends of each cut. MSA1 is a one-point back-fed flat antenna, and its cross-sectional view is shown in FIG. Power supply pin 1a
Pass through the through hole 4 of the conductor plate 4 in a non-contact manner and is connected to a signal transmission line such as a coaxial line.

The MSA 1 is designed by appropriately designing parameters such as relative permittivity and dimensions of the dielectric substrate 1c, dimensions of the patch-shaped radiating element 1b to be attached to the dielectric substrate 1c, positions of the feeding pins 1a, and the like. It operates as a circularly polarized antenna at a frequency of. However, the impedance matching by the resonance frequency and the position of the feed pin 1a is performed by the helical radiating element 2.
Care must be taken because it depends on the length and width of b.

FIG. 3 shows a radiating element 2b for comparison with FIG.
A conventional wide-angle circularly polarized antenna having no cutout and having the same configuration as that of FIG. 1 except that the cutout 7 and the small-diameter coil 8 are not provided. Therefore, a description will be given with reference to FIGS. 1 and 3 (comparative example). The operating frequency of the antenna is 1.6
GHz band. The widths of the conductor portions 2e are all 7 mm, and the widths of the helical radiating elements 2b are all 4.5 mm.
A square microstrip planar antenna according to the embodiment of the present invention in FIG. 1 (substrate size 28 × 28 × 12 mm)
1 is a supporting cylinder 2a (diameter 30 mm, height 135 mm)
It is supported by. Helical radiating element (about 136mm)
A cut 7 is made in a part of 2b, and the small-diameter coil 8 is electrically connected in the vicinity of the cut 7. Support cylinder 2a
Has a height of 135 mm.

The height of the supporting cylinder 2a in FIG. 3 is 140 mm, and the length of the helical radiating element 2b is about 141 m.
m. That is, as shown in FIG. 1, according to the present invention, the directivity of the wide-angle circularly polarized antenna is corrected by correcting the electrical length of the radiating element by using the small-diameter coil 8 with the difference of 5 mm in the length of the radiating element. To keep.

The helical radiating element 2b is wound down by 180 degrees, and at the lower end, two opposing sets of helical radiating elements are connected to each other by a covered conductor (not shown). At this time, the covered wires crossing at the lower end are not connected in terms of direct current.

FIGS. 4 and 5 show examples of actually measuring the wide-angle circularly polarized antennas of FIGS. 1 and 3. FIG. Further, FIG. 6 shows an example of actual measurement of a wide-angle circularly polarized antenna assembled with the dimensions of FIG. 1 and without the cut 7 and without the small-diameter coil 8.
Shown in Although the height (length of the helical portion) of the support cylinder 2a is different between FIG. 4 and FIG. 5, the radiation patterns show almost the same tendency. On the other hand, FIG. 6 has the same height (length of the helical portion) of the supporting cylinder as that of FIG. 4, but the gain is degraded at a low elevation angle.

In the embodiment of the present invention, one small-diameter coil 8 is inserted into each of the four helical radiating elements 2b, but the size of the small-diameter coil 8, the width of the notch 7, the position of the small-diameter coil 8, By appropriately arranging the quantity, further miniaturization is possible.

Although the microstrip planar antenna has been described as an example of a quadrilateral, the shape of the microstrip planar antenna is circular, triangular, pentagonal or the like.
The shape of the helical radiating element is not limited, such as a prism or a pentagonal prism.
Further, the feeding method of the microstrip planar antenna is not limited to the one-point back feeding type. Also, an example has been described in which the four-wire helical antenna is disposed substantially coaxially below the ground conductor plate of the microstrip planar antenna, but the helical antenna may be an eight-wire helical antenna or the like, and is not limited to the four-wire helical antenna.

[0015]

According to the above configuration, the helical radiating element of the wide-angle circularly polarized antenna can be electrically shortened, and the antenna can be reduced in size without affecting the radiation pattern shape of the antenna.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wide-angle circularly polarized antenna according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a microstrip planar antenna portion of a wide-angle circularly polarized antenna.

FIG. 3 is a configuration diagram of a conventional wide-angle circularly polarized antenna.

FIG. 4 shows an example of a radiation pattern in FIG. 1 (length of a helical portion is 135 mm, and a small-diameter coil is inserted).

FIG. 5 is an example of a radiation pattern in FIG. 3 (a helical portion has a length of 140 mm).

FIG. 6 is a diagram showing a helical radiating element 7 having a cut length of 135 mm without a cut and a small-diameter coil 8;
Example of radiation pattern of conventional wide-angle circularly polarized antenna shortened.

[Explanation of symbols]

1: Microstrip planar antenna (MSA) 1a: Feeding pin of MSA 1b: Patch-shaped radiating element of MSA 1c: Dielectric substrate of MSA 2: Helical portion 2a: Dielectric supporting cylinder supporting helical portion 2b: Helical shape 2c: Insulator that prevents the radiating elements from contacting each other at the intersection of the lower end of the helical antenna 2d: Intersection of the radiating element provided at the lower end of the helical antenna 2e: Conductor (edge) 3: Feeding point 4: Ground conductor (conductor plate) of MSA 4a: Through hole of conductor plate 6: Signal transmission path 7: Cut 8: Small diameter coil

Claims (2)

[Claims] 1. A microstrip planar antenna having a circularly polarized mode in which a conductor plate serving as a common ground conductor is provided, and a patch-shaped radiating element is arranged in parallel on the conductor plate via a dielectric layer. A linear radiating element is wound under the conductor plate in a helical manner substantially coaxially with the microstrip planar antenna, and the upper end of the helical linear radiating element is directly or capacitively coupled to the conductor plate. A helical antenna is formed, and a small-diameter coil is inserted in the middle of the helical linear radiating element. 2. The method according to claim 1, wherein the number of said helical linear radiating elements is four or more, and at least one small-diameter coil is inserted in all linear radiating elements in series. 2. The wide-angle circularly polarized antenna according to 1.