JPS61210707A - Antenna system - Google Patents

Abstract

PURPOSE:To execute the resonance even when the interval between an electric conductor plate and a case is sufficiently narrowed by providing the metallic member to give equally the effect of the capacitance such as a metallic bridge plate or a metallic member between the electric conductor plate and the case. CONSTITUTION:For a metallic bridge plate 5, in which the plate of the metallic material is bent in a U-shape, both edges are grounded to a case 3 and provided between a conductor plate 2 and a case 3. In the antenna constituted like this, the part between the electric conductor plate 2 and the metallic bridge plate 5 executes equally the function of the capacitance, and the input impedance characteristic is improved when the interval between the electric conductor 2 and the case 3. Namely, the metallic bridge plate or the metallic member such as the metallic block executes equally the function of the capacitance, the input impedance close to the short-circuit condition is improved and the resonance condition of the antenna is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small antenna device with excellent impedance characteristics.

[Conventional technology]

A conventional antenna device of this type is shown in FIG.

In the figure, (1) is the power supply element, (2) is the conductor plate, and (3
) is a casing made of metal, and (4) is a ground conductor. This antenna device is configured as described above, and the power fed through the feed element (υ) excites radio waves between the conductor plate (2) and the casing (3). When the size of the conductor plate (2) is small compared to the wavelength, the ground conductor (4) effectively serves to lower the resonant frequency of this antenna device.

[Problem that the invention seeks to solve]

In the conventional antenna device configured as described above, as the distance between the conductor plate (2) and the housing (3) is narrowed, the input impedance seen from the feed point of the feed element (1) becomes worse and short circuits occur. getting closer to the situation. Therefore, when attempting to construct an antenna device Mtkm that is sufficiently small compared to the wavelength, there is a problem in that the ground conductor (4) alone has little effect and it is difficult to make it resonate. The purpose of this invention is to obtain an antenna device which resonates even when the distance between the conductor plate (2) and the housing (3) is sufficiently narrowed.

[Means for solving problems]

The antenna device according to the present invention is provided between a casing and a metal bridge plate or a metal block, which is a metal bridge plate with both ends of a metal plate bent.

[Effect]

In this invention, a metal member such as a metal bridge plate or a metal block equivalently functions as a capacitance, improves the input impedance approaching a short circuit state, and brings the antenna into a resonant state.

〔Example〕

FIG. 1 is a perspective view of an antenna device showing an embodiment of the present invention. In the figure, (1) to (1) are the same or equivalent members to those of the conventional device described above. (5) is a perspective view of an antenna device showing an embodiment of the present invention. This is a metal bridge plate made by bending a metal plate into a U-shape.Both ends of the plate are grounded to the casing (3), and the four-body plate (2) and the casing (
3).

In the antenna device configured as described above, the portion between the conductor plate (2) and the metal bridge plate (5) equivalently functions as a capacitance, and the portion between the conductor plate (2) and the casing (3) functions as a capacitance.
The input impedance characteristics will be improved if the spacing is narrowed.

FIG. 2 is a characteristic curve diagram showing the input impedance vf characteristics in this embodiment. In the figure, (a) is the input impedance characteristic without the metal bridge plate.
The distance between the conductor plate (2) and the housing (3) is 0.006λ (λ;
wavelength). (γ) is the input impedance characteristic with a metal bridge plate. That is, it can be seen that capacitance is equivalently introduced in parallel by the metal bridge plate (5), and that this antenna device resonates. In addition, in the figure, f.

indicates the center frequency.

FIG. 6 is a perspective view of an antenna device showing another embodiment of the invention. In the figure, (1) to (4) are the same or equivalent members to the conventional device shown in FIG.

(3) is a metal block made of metal material, and the housing (3) is a metal block made of metal material.
). In this embodiment as well, the portion between the conductor plate (2) and the metal block (3) functions equivalently as a capacitance, and as in the case of the embodiment shown in FIG. Input impedance characteristics improve when the spacing between the casings (3) is narrowed.

FIG. 4 is a perspective view of an antenna device showing still another embodiment of the present invention. In the figure, (1) to (4) are the fifth
The components are the same as or equivalent to the components of the conventional device shown in the figure. Further, (5) is the same metal bridge plate as in the embodiment shown in FIG. +91, (92) is a dielectric, and the metal bridge plate (5) is provided between the dielectric (91) and the dielectric (92). In this example, the dielectrics (91) and (92) are separate bodies in order to interpose the metal bridge plate (5), but these dielectrics (91) and (92) may be integrated and loaded. . Therefore, this dielectric (91), (
92) -5= Since the wavelength of the radio wave is shortened, when the size of the conductor plate (2) is equal to the size without the dielectrics (91) and (92), this antenna will resonate. This will make it easier.

Note that although the above description has been made regarding the case of transmitting radio waves, it is of course possible to apply the present invention to the case of receiving radio waves. Further, the shape of the conductor plate (2) may be polygonal, circular, etc.
Furthermore, the shape of the housing is not limited to a hexahedron. In addition, the metal bridge plate (5) and the metal block (3) only need to provide an equivalent capacitance effect, and therefore,
It may be grounded to the conductor plate instead of the case. Further, a plurality of these metal bridge plates (5) and metal blocks (3) may be used.

〔Effect of the invention〕

As explained above, this invention provides a metal member, such as a metal bridge plate or a metal block, between the conductor plate and the casing, which equivalently provides a capacitance effect.
Furthermore, by loading a dielectric between the conductor plate and the housing and interposing the metal member within this dielectric, the wavelength of the radio wave can be shortened and the distance between the conductor plate and the housing can be narrowed. The antenna device can be made to resonate, and a small antenna device with excellent impedance characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an antenna device showing one embodiment of the present invention, Fig. 2-1 is a characteristic curve diagram showing the input impedance characteristics of the above antenna equipment, and Fig. 6 shows another embodiment of the invention. FIG. 4 is a perspective view of an antenna device showing still another embodiment of the present invention, and FIG. 5 is a perspective view of a conventional antenna device. In the figure, (1) is the power supply element, (2) is the monument plate, and (3
) is the casing, (4) is the ground conductor, (5) is the metal bridge plate, (3) is the metal block, and (91) and (92) are the dielectrics. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) A casing made of metal, a conductor plate placed close to the casing, a connecting conductor connecting the casing and the conductor plate, and a connection between the casing and the conductor plate. 1. An antenna device comprising a feeding element that feeds power with a power supply element, characterized in that a metal member is provided between the casing and the conductor plate, the metal member being grounded to either one of the casing and the conductor plate and serving as equivalent capacitance. (2) The antenna device according to claim 1, wherein the metal member is a metal bridge plate with both ends of a metal plate bent into a U-shape. (3) The antenna device according to claim 1, wherein the metal member is a metal block. (4) The antenna device according to claim 1, wherein the metal member is interposed within a dielectric material loaded between the casing and the conductor plate in order to shorten the wavelength of radio waves.