JPH04357702A - Plane antenna - Google Patents

Abstract

PURPOSE:To realize the plane antenna formed to be a thin profile even under the condition of both transmission/reception and circularly polarized wave excitation whose transmission reception frequencies are apart by several% or over. CONSTITUTION:A circular radiation conductor 11 and a torus radiation conductor 12 are arranged opposite to a ground conductor 3. The outer circumference of the radiation conductor 12 is connected to the ground conductor 3. The radiation conductors 11, 12 are arranged concentrically on a same plane and a distance (d) is set smaller than a thickness (t) (thickness of board) of, e.g. a dielectric body 2 to cause inter-coupling. The size of the radiation conductors 11, 12 are selected to be excited in the same modes in an optional frequency band. Two frequencies are used in resonance with the radiation conductors 11, 12 by having only to a feeding point 4 to the radiation conductor 11 by the effect of inter-linking. Since the conductors are resonated in the two frequencies, the conductors are applied to both the transmission/reception antennas whose transmission reception frequencies are apart by several% or over and the antenna copes with excitation of a circularly polarized wave by applying two-point feeding with a phase difference of, e.g. 90 deg. and the merit of the thin profile is sufficiently utilized because of single layer structure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna in which a ground conductor and a radiation conductor are arranged facing each other with a dielectric interposed therebetween.

0002

2. Description of the Related Art Microstrip antennas are known as planar antennas, and circular patch antennas and rectangular patch antennas are known as microstrip antennas.

First, a circular patch antenna will be explained. FIG. 5A is a plan view of the circular patch antenna, and FIG. 5B is a cross-sectional view taken along the line II.

In the figure, 1 is a circular radiation conductor, 2 is a circular dielectric, and 3 is a circular ground conductor. Radiation conductor 1
is formed facing the ground conductor 3 with the dielectric 2 in between. The dielectric 2 and the ground conductor 3 are of the same size, and the radiation conductor 1 is printed smaller than these. As the dielectric material 2, for example, Teflon fiberglass (relative permittivity is 2
．． 6) is used.

[0005] Furthermore, a feeding point 4 is provided at a position offset from the center of the radiation conductor 1, and this feeding point 4 is connected to the internal conductor of a feeding port (connector) 5 arranged on the grounding conductor 3 side. . The outer conductor of this power supply port 5 is connected to the ground conductor 3.

[0006]

[Problems to be Solved by the Invention] The patch antenna described above has many features such as being simple in structure, thin and durable, but generally has a high Q value and a narrow frequency band.

For example, in the case of the circular patch antenna shown in FIG. 5, its resonant frequency f in the lowest order mode TM11 is determined by Equation 1. In this equation, C is the speed of light, r
f is the radius of the radiation conductor 1, t is the thickness of the dielectric 2, εr
is the relative permittivity of the dielectric 2, x is the eigenvalue of the eigenfunction specific to the shape of the radiation conductor 1, and for a circular patch antenna, x=
It is 1.841.

[0008]

[Math 1]

[0009] The band of the circular patch antenna is return loss≦-10 dB, and only a few percent of the band can be obtained around the resonant frequency f. FIG. 6 shows rf = 17.5 mm, t = 1.
6mm, εr = 2.6, diameter D of ground conductor 3 = 90m
This is a measurement result of the return loss of a circular patch antenna when m. In this example, fo =2976MHz
The frequency bandwidth BW is 54 MHz (1.8
2%).

[0010] Conventionally, a wireless communication system is known that is constructed between a base station on the ground and a mobile station using a geostationary satellite as a relay.

In such a communication system, downlinks are constructed from a base station to a large number of mobile stations via satellites, and uplinks are constructed from each mobile station to the base station. In this case, the frequencies of transmission and reception are made to be different.

[0012] In such a communication system, when the transmitting and receiving frequencies differ by more than a few percent, the above-mentioned patch antenna cannot be applied to the transmitting and receiving antenna of this communication system.

Various methods have been proposed to overcome the drawbacks of patch antennas, but when the condition of circularly polarized wave excitation is added, the methods are quite limited and have only been proposed as a practical method. There is a stacked patch antenna (C.H. Chen, A. Tulin).
tseff and R. M. Sorbello:
Broadband Two-Layer Micro
strip antenna”, 1984 IEEE
AP-S Int. Symp. Dig. pp. 251
-254).

FIG. 7 shows the configuration of a stacked patch antenna, and parts corresponding to those in FIG. 5 are designated by the same reference numerals. FIG. 7A is a plan view, and FIG. 7B is a sectional view taken along the line I-I.

[0015] The stacked patch antenna has a radiation conductor 1
A dielectric 6, a radiation conductor 7, and a dielectric 8 are further laminated in this order on top of the structure.

This stacked patch antenna has a two-resonance type characteristic, and the frequency interval between two waves can be controlled by adjusting the stack interval S (thickness of the dielectric 6).

However, as is clear from FIG. 7, the stacked patch antenna has a two-layer structure, which increases the overall thickness, which negates the original thinness of the planar antenna. there were.

Accordingly, the present invention provides a planar antenna that can be constructed thinly even under the conditions of dual use for transmitting and receiving and circularly polarized wave excitation in which the transmitting and receiving frequencies are separated by several percent or more.

[0019]

[Means for Solving the Problems] The present invention provides a planar antenna in which a ground conductor and a radiating conductor are arranged facing each other with a dielectric interposed therebetween, in which a flat radiating conductor and a ring-shaped radiating conductor are on the same plane as the radiating conductors. The ring-shaped radiating conductor is arranged concentrically with the ground conductor, and a part or all of it is connected to the ground conductor along the entire outer circumference of the ring-shaped radiating conductor, and the flat plate-shaped radiating conductor and the ring-shaped radiating conductor are excited in the same mode in any frequency band. The size is as follows.

[0020]

[Function] Since the flat radiation conductor and the ring radiation conductor are arranged, the antenna resonates at two frequencies, and can be applied to a transmitting and receiving antenna where the transmitting and receiving frequencies are separated by several percentage points or more. Furthermore, since independent orthogonal modes are maintained at each frequency, circularly polarized wave excitation can also be supported by performing two-point power feeding with a phase difference of 90°, for example. Furthermore, since the flat radiation conductor and the ring radiation conductor are arranged on the same plane, it is possible to take advantage of the inherent thinness of the flat antenna.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Figure 1A is a plan view, Figure 1B is an I-
It is an I line sectional view. In FIG. 1, parts corresponding to those in FIG. 5 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, a circular radiation conductor 11 and an annular radiation conductor 12 are arranged opposite to the ground conductor 3. Radiation conductors 11 and 12 are arranged concentrically on the same plane. The outer peripheral portion of the radiation conductor 12 is connected to the ground conductor 3.

The distance d between the radiation conductors 11 and 12 is set to be smaller than, for example, the thickness t of the dielectric 2 (substrate thickness) so that mutual coupling occurs between the radiation conductors.

The radiation conductors 11 and 12 are made to have a size that allows them to be excited in the same mode, for example, the TM11 mode, in any frequency band.

Further, a feeding point 4 is provided at a position offset from the center of the radiation conductor 11, and this feeding point 4 is connected to the internal conductor of a feeding port (connector) 5 arranged on the grounding conductor 3 side. . The outer conductor of the power supply port 5 is connected to the ground conductor 3.

Since the radiation conductors 11 and 12 are coupled to each other as described above, simply by providing the feed port 5 to the radiation conductor 11, the frequencies that resonate with the radiation conductor 11 and the frequencies that resonate with the radiation conductor 12 can be changed. It can be used in 2 waves. Note that the power feeding port 5 may be provided to the radiation conductor 12.

The present example is constructed as described above, and the circular radiation conductor 11 and the annular radiation conductor 12 are each excited in the same mode in an arbitrary frequency band, and resonate at two frequencies. The frequency interval between the two waves is controlled by adjusting the distance d between the radiation conductors and changing the amount of mutual coupling.

FIG. 2 shows the radius ra = 17 of the radiation conductor 11.
．． 5mm, inner radius rb of radiation conductor 12 = 18.5m
m, its outer radius rc = 35.5 mm, the distance between the radiating conductors d = 1.0 mm, the thickness of the dielectric 2 t = 1.6 mm, and the relative permittivity εr of the dielectric 2 = 2.6. These are the measurement results. Note that the connection between the outer peripheral portion of the radiation conductor 12 and the ground conductor 3 is achieved by arranging 64 through holes of φ=0.4 mm at equal intervals over the entire circumference.

This example is designed so that the radiation conductors 11 and 12 are excited in the TM11 mode in the 3 GHz band. As a result, f1=2964MHz and f2
= resonates at 3178MHz, f2-f1=214MHz
(approximately 6.97%) It can be shared by two frequencies separated by approximately 6.97%.

[0030] Thus, according to this example, the antenna resonates at two frequencies, and can be applied to a dual-purpose antenna in which the transmitting and receiving frequencies are separated by several percentage points or more.

Furthermore, as in the case of a stacked patch antenna, since independent orthogonal modes are maintained at each frequency, for example, as shown in FIG. By providing 4B and feeding power, circularly polarized wave excitation can also be supported.

Furthermore, compared to a stacked patch antenna, since it has a single layer structure, it is possible to fully utilize the advantage of being thin, which is the original feature of a planar antenna.

Note that in the above embodiment, the radiation conductor 1
When connecting the outer periphery of the radiation conductor 2 to the grounding conductor 3, the conductor part of the radiation conductor 12 is extended to connect the entire part, but as shown in Fig. The parts may be connected. In this case, as long as the spacing between the through holes 13, pins, etc. is equal to or less than the thickness t of the dielectric 2, an effect substantially equivalent to that of full grounding can be obtained.

Further, in the above embodiment, the flat radiation conductor is circular and the annular radiation conductor is circular, but squares, combinations of rectangular rings, and other shapes may be constructed in the same manner. Can be done.

[0035]

According to the present invention, since a flat radiation conductor and an annular radiation conductor are arranged, the antenna resonates at two frequencies, and can be applied to a transmitting and receiving antenna in which the transmitting and receiving frequencies are separated by several percentage points or more. Further, since independent orthogonal modes are maintained at each frequency, it is possible to support circularly polarized wave excitation by performing two-point power feeding with a phase difference of 90°, for example. Furthermore, since the flat radiation conductor and the ring radiation conductor are arranged on the same plane, the inherent thinness of the flat antenna can be fully utilized.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a diagram showing return loss in an example.

FIG. 3 is a configuration diagram of another embodiment (circularly polarized wave).

FIG. 4 is a configuration diagram of another embodiment.

FIG. 5 is a configuration diagram of a circular patch antenna.

FIG. 6 is a diagram showing return loss of a circular patch antenna.

FIG. 7 is a configuration diagram of a stacked patch antenna.

[Explanation of symbols]

2 Dielectric material 3 Ground conductor 4, 4A, 4B power supply point 5 Power supply port (connector) 11 Circular radiation conductor 12 Annular radiation conductor 13 Through hole

Claims (2)

[Claims] 1. A planar antenna in which a ground conductor and a radiating conductor are arranged facing each other with a dielectric interposed therebetween, wherein a flat radiating conductor and a ring-shaped radiating conductor are arranged concentrically on the same plane as the radiating conductors, Part or all of the outer circumference of the annular radiating conductor is connected to the grounding conductor, and the flat radiating conductor and the annular radiating conductor have a size that excites them in the same mode in any frequency band. A planar antenna with. 2. The planar antenna according to claim 1, wherein the flat radiation conductor is circular and the annular radiation conductor is circular.