JPH0514047A - Slot antenna by coaxial flat resonator - Google Patents

Abstract

PURPOSE:To mount the antenna to the inside and the outside of a radio equipment by making the occupied volume of the slot antenna by a coaxial resonator flat through the reduction of the height, keeping the flat size within a 1/2 wavelength equivalent to the resonance frequency so as to obtain the frequency characteristic with an excellent impedance matching performance. CONSTITUTION:The antenna consists of a conductor strip 6 being a signal transmission line parted into upper and lower opposite faces 2-1, 2-2 of the resonator 1 along the resonance axial direction, a thin and long slot 5 opened to any or both end ridges of the upper and lower faces crossed providing a space to the conductor strip and separated from the coaxial line 4 and a coaxial line having a prolonged conductor 4-2 parted and extended along the conductor strip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot antenna using a coaxial flat resonator, which is suitable for application to the field of ultra high frequencies such as cellular automobile telephones.

[0002]

2. Description of the Related Art Generally, in a coaxial resonator having a frequency of more than 3 GHz, the attenuation of the transmission frequency caused by the dielectric material supporting the center conductor of the coaxial line drops to about 1 decibel per meter, and It is unsuitable for high power transmission because it causes the deterioration of the dielectric due to the heat loss of, but when the electromagnetic wave is transmitted as a cavity resonator, the heat loss is limited to this inner wall, and it is about 1% of the coaxial line. It is known that it can be reduced to.

The electromagnetic field of the resonator is the TE _mnp mode (m,
n and p are both designed to resonate with a positive integer of 0 or more), but the resonance length is such that when both ends of the resonator are terminated, the dimensions of the resonator are a and a as shown in FIG. b and c, the central value λ ₀ of the resonance wavelength is {(m / 2a) ² + (n /
2b) ² + (p / 2c) ² } is expressed by 1 / square root.

[0004]

When the dimensions of the cavity resonator shown in FIG. 1 are a, c> b, for example, the fundamental mode of the resonator is TE ₁₀₁ , so that m = 1, n = 0, p =
When the resonance frequency λ ₀ is calculated as 1, {(1 / 2a) ²
It becomes 1 / square root of + (1 / 2c) ² }, and the dimensions of at least two sides of the rectangular parallelepiped resonator must be taken to be approximately the same as the guide wavelength corresponding to the operating frequency. It is difficult to reduce the external dimensions. In addition, when the height b is made small, there is a difficulty that the resonance frequency and the frequency bandwidth cannot be easily determined because the parameters are complicatedly entangled with each other. If it is taken long or the interval between the opposed slots is made small, the interaction causes interference and impedance matching cannot be taken, resulting in deterioration of characteristics.In the end, the frequency bandwidth cannot be expanded and the cavity resonator cannot be expanded. There was a technical problem of increasing the external dimensions of itself.

[0005]

According to the present invention, in order to improve impedance matching and frequency characteristics by flattening the thickness of the resonator occupying the entire volume of the slot antenna by the coaxial resonator, the axial direction is improved. For the signal transmission path laid along the upper and lower resonators along the resonator,
Whether the coaxial flat resonator itself is housed in the exterior of the radio by providing the extension of the coaxial feed line introduced into the slot opening surface of one or both sides with the signal transmission path locally and separately from the signal transmission path. It is designed so that it can be placed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of a slot antenna using the coaxial flat resonator of the present invention will be described in detail below with reference to FIGS. Throughout the drawings, the same reference numerals are given to the same portions, and duplicated portions will be omitted for the sake of explanation.

First, in FIG. 2, the cavity resonator 1 is formed in a box made of a flat rectangular parallelepiped conductive material, and is spatially separated from the upper surface 2-1 and the lower surface 2-2 in the resonator, and the resonance axial direction. A thin conductor strip 6 is mounted on the base. Then, a slot 5 is opened at an edge of the upper surface so as to be spaced apart from and cross the conductor band, and a central conductor of the coaxial line 4 is introduced from a side opposite to the edge, and an extension conductor 4-which is a tip end thereof. As shown in FIG. 3, the parts 2 are locally arranged along the same electric conductor strip.

Next, FIG. 4 shows an embodiment in which a slot 5-2 is also opened on the lower surface 2-2 facing the slot 5 of FIG.

Thus, according to the configuration of the present invention, the resonator 1
The signal input through the conductor layer 6 in the inside and the extension conductor 4-2 in which the central conductor 4-1 of the coaxial line 4 extends propagates by electromagnetic coupling in the flat cavity resonator and resonates in the TEM mode. The resonator is excited by electromagnetic coupling with a slot opened on the upper or lower surface which is an outer conductor of the resonator, and radiates an electromagnetic wave.

[0010]

According to the present invention, the extension conductor extending the central conductor of the coaxial line along the conductor band is introduced into the conductor by magnetic field coupling, and is opened on the outer surface of the resonator by the resonance action of the TEM mode. Since the slots to be excited are electromagnetically coupled and excited, it is possible to obtain a slot antenna having frequency characteristics with good impedance matching.

Further, although the height of the resonator itself is made extremely low to make it flat, the planar size of the resonator can be suppressed within one-half wavelength of the resonance frequency. The flatness of the exterior of the wireless device has been approached as the
It becomes possible to adapt the inside of the exterior body to the exterior.

[Brief description of drawings]

FIG. 1 is a perspective view of a coaxial cavity resonator for explaining the basic principle of the present invention.

FIG. 2 is a transparent perspective view of a slot antenna using the coaxial flat resonator of the present invention.

FIG. 3 is a vertical sectional side view of FIG.

FIG. 4 is a transparent perspective view of a different embodiment of the present invention.

[Explanation of symbols]

 1 Resonator 2-1 Upper surface 2-2 Lower surface 4 Coaxial line 4-1 Center conductor 5, 5-1, 5-2 Slot 6 Conductor band

Claims (1)

Claim: What is claimed is: 1. A slot antenna using a coaxial resonator of a TEM mode, wherein a flat rectangular parallelepiped resonator having a half wavelength of a resonance frequency in the axial direction and the resonance along the axial direction. A conductor band serving as a signal transmission path that is laid spatially between the upper and lower facing surfaces of the resonator and a top surface of the resonator that intersects the conductor band at a space and is separated from the coaxial line. Or a coaxial line having an elongated slot opening to the lower surface and an extension conductor introduced at an edge opposite to the slot opening and extending along the conductor band at a space. Slot antenna with coaxial flat resonator.