JP3003272B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna having a ground conductor and a radiating conductor opposed to each other via a dielectric.

[0002]

2. Description of the Related Art A microstrip antenna is known as a planar antenna, and a circular patch antenna and a square patch antenna are known as microstrip antennas.

[0003] First, a circular patch antenna will be described. FIG. 5A is a plan view of a circular patch antenna, and FIG. 5B is a cross-sectional view taken along the line II.

In FIG. 1, 1 is a circular radiation conductor, 2 is a circular dielectric, and 3 is a circular ground conductor. Radiating conductor 1
Are formed facing the ground conductor 3 with the dielectric 2 interposed therebetween.
The dielectric 2 and the ground conductor 3 have the same size, and the radiation conductor 1 is formed by printing smaller than these. As the dielectric 2, for example, Teflon fiberglass (having a relative dielectric constant of 2.6) is used.

The radiation conductor 1 is provided with a feed point 4 at a position offset from the center, and the feed point 4 is connected to an internal conductor of a feed port (connector) 5 arranged on the ground conductor 3 side. . The outer conductor of the power supply port 5 is connected to the ground conductor 3.

[0006]

The above-described patch antenna has many features such as a simple structure, a thin structure, and a toughness, but generally has a high Q and a narrow frequency band.

[0007] For example, for a circular patch antenna shown in FIG. 5, the resonance frequency f, in the lowest-order mode TM _11, it is determined by the number 1. In this equation, C is the speed of light, rf
Is the radius of the radiating conductor 1, t is the thickness of the dielectric 2, εr is the relative permittivity of the dielectric 2, x is the eigenvalue of an eigenfunction unique to the shape of the radiating conductor 1, and x = 1. 8
41.

[0008]

(Equation 1)

[0009] The band of the circular patch antenna has a return loss of -10 dB, and only about a few% around the resonance frequency f can be obtained. FIG. 6 shows that rf = 17.5 mm and t = 1.6.
5 is a measurement result of the return loss of the circular patch antenna when mm, εr = 2.6, and the diameter D of the ground conductor 3 is 90 mm. In this example, resonance occurs at fo = 2976 MHz, and its frequency bandwidth BW is 54 MHz (1.82%).
It is.

Conventionally, there has been known a radio communication system configured between a base station and a mobile station on the ground using a geostationary satellite as a relay.

In such a communication system, a downlink is formed from the base station to a number of mobile stations via satellites, and an uplink is formed from each mobile station to the base station. In this case, the transmission and reception frequencies are made different.

In such a communication system, when the transmission and reception frequencies are separated by several percent or more, the above-mentioned patch antenna cannot be applied to the transmission / reception antenna of the communication system.

Various methods have been proposed as methods for overcoming the drawbacks of the patch antenna. However, if the condition of circularly polarized wave excitation is added, the methods are considerably limited, and are proposed as the only practical methods. There is a stack type patch antenna (CHChen, A. Tulintseff and RMSor
bello: Broadband Two-Layer Microstrip Antenna ", 19
84 IEEE AP-S Int.Symp.Dig. Pp.251-254).

FIG. 7 shows a configuration of a stack type patch antenna, and portions corresponding to FIG. 5 are denoted by the same reference numerals. FIG. 7A is a plan view, and FIG. 7B is a sectional view taken along line II.

The stack type patch antenna has a radiation conductor 1.
On top of this, a dielectric 6, a radiation conductor 7, and a dielectric 8 are further laminated in this order.

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

However, as is apparent from FIG. 7, the stack type patch antenna has a two-layer structure, and therefore has a disadvantage that the overall thickness is increased and the inherent thinness of the flat antenna is invalidated. there were.

In view of the above, the present invention provides a planar antenna that can be made thin even under the conditions of both transmitting and receiving frequencies and a circularly polarized wave excitation in which the transmitting and receiving frequencies are separated by several percent or more.

[0019]

A planar antenna according to the present invention is a planar antenna in which a ground conductor and a radiation conductor are arranged to face each other with a dielectric interposed therebetween. A ring-shaped radiation conductor is concentrically arranged on the same plane, and a part or all of the ring-shaped radiation conductor is connected to the ground conductor over the entire outer periphery of the ring-shaped radiation conductor. It has a magnitude to excite in the same mode by mutual coupling in the frequency band.

[0020]

Since the plate-shaped radiating conductor and the ring-shaped radiating conductor are arranged, they resonate at two frequencies, and can be applied to a transmitting / receiving antenna whose transmission / reception frequency is separated by several percent or more. In addition, since the independent orthogonal mode is maintained at each frequency, it is possible to cope with circularly polarized wave excitation by feeding two points with a phase difference of 90 °, for example.
Further, since the flat radiating conductor and the annular radiating conductor are arranged on the same plane, it is possible to take advantage of the inherent thinness of the planar antenna.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1A is a plan view, and FIG.
It is an I line sectional view. In FIG. 1, portions corresponding to FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, a circular radiating conductor 11 and an annular radiating conductor 12 are arranged opposite to the ground conductor 3. The 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 radiating conductors 11 and 12 is set smaller than, for example, the thickness t (substrate thickness) of the dielectric 2 so that mutual coupling occurs between the radiating conductors.

The radiating conductor 11 and 12 is at any frequency band, same mode respectively, for example, to have a magnitude excited in TM ₁₁ mode.

The radiating conductor 11 is provided with a feed point 4 at a position offset from the center, and the feed point 4 is connected to an internal conductor of a feed port (connector) 5 arranged on the ground conductor 3 side. . The outer conductor of the power supply port 5 is connected to the ground conductor 3.

Since the radiating conductors 11 and 12 are mutually coupled as described above, only the provision of the feed port 5 for the radiating conductor 11 allows the frequency at which the radiating conductor 11 resonates and the frequency at which the radiating conductor 12 resonates to be increased. It can be used in two waves. Note that the power supply port 5 may be provided for the radiation conductor 12.

The present embodiment is configured as described above, and the circular radiation conductor 11 and the annular radiation conductor 12 are 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 radiation conductor interval d to change the amount of mutual coupling.

FIG. 2 shows the radius ra of the radiation conductor 11 = 17.
5 mm, inner radius rb of radiation conductor 12 = 18.5 mm,
The outer radius rc = 35.5 mm, and the radiation conductor interval d =
1.0 mm, thickness t of dielectric 2 = 1.6 mm, dielectric 2
5 is a measurement result of the return loss when the relative dielectric constant εr = 2.6. Note that the connection of the outer peripheral portion of the radiation conductor 12 to the ground conductor 3 is performed by arranging 64 through holes of φ = 0.4 mm over the entire circumference at equal intervals.

[0029] This example, in 3GHz band, in which the radiation conductor 11 and 12 is designed to excite in the TM ₁₁ mode. As a result, f1 = 2964 MHz and f2 =
Resonates at 3178 MHz, f2-f1 = 214 MHz
(Approximately 6.97%) It can be shared by two separated frequencies.

As described above, according to this embodiment, the antenna resonates at two frequencies, and can be applied to a transmitting / receiving antenna whose transmission / reception frequency is separated by several percent or more.

Further, as in the case of the stack type patch antenna, an independent orthogonal mode is maintained at each frequency. Therefore, as shown in FIG. 3, for example, as shown in FIG. By providing power supply with 4B, it is possible to cope with circularly polarized wave excitation.

Further, compared with the stack type patch antenna, since it has a one-layer structure, it is possible to sufficiently make use of the advantage of the thinness which is an inherent feature of the planar antenna.

In the above embodiment, the radiation conductor 1
When connecting the outer peripheral portion of the radiating conductor 2 to the ground conductor 3, the conductor portion of the radiation conductor 12 is extended so as to connect all of the radiating conductor 12, but as shown in FIG. The units may be connected. In this case, as far as the spacing between the through holes 13 or the pins and the like is equal to or less than the thickness t of the dielectric 2, substantially the same effect as the whole grounding can be obtained.

In the above-described embodiment, the flat radiating conductor is circular and the annular radiating conductor is circular. However, a combination of a rectangular shape, a rectangular shape, and other shapes may be similarly configured. Can be.

[0035]

According to the present invention, since the flat radiating conductor and the ring-shaped radiating conductor are arranged, they resonate at two frequencies, and can be applied to a transmitting / receiving antenna whose transmission / reception frequencies are separated by several percent or more. Further, since the independent orthogonal mode is maintained at each frequency, it is possible to cope with circularly polarized wave excitation by performing two-point power supply with a phase difference of 90 °, for example. Further, since the flat radiating conductor and the ring radiating conductor are arranged on the same plane, it is possible to make full use of the inherent thinness of the planar antenna.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a diagram showing a return loss of the embodiment.

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 illustrating return loss of a circular patch antenna.

FIG. 7 is a configuration diagram of a stack type patch antenna.

[Explanation of symbols]

 2 Dielectric 3 Ground conductor 4, 4A, 4B Feeding point 5 Feeding port (connector) 11 Circular radiating conductor 12 Toroidal radiating conductor 13 Through hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-107203 (JP, A) JP-A-1-189208 (JP, A) JP-A-58-166807 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01Q 13/08 H01Q 5/00

Claims (2)

(57) [Claims] 1. A planar antenna in which a ground conductor and a radiation conductor are disposed to face each other via a dielectric, wherein a flat radiation conductor and a ring radiation conductor are concentrically disposed on the same plane as the radiation conductor. A part or all of the ring-shaped radiation conductor is connected to the ground conductor over the entire outer periphery of the ring-shaped radiation conductor, and the plate-shaped radiation conductor and the ring-shaped radiation conductor are excited in the same mode by mutual coupling in an arbitrary frequency band. A planar antenna having a size. 2. The planar antenna according to claim 1, wherein said flat radiating conductor is circular and said annular radiating conductor is circular.