JPS63254806A - Microstrip antenna - Google Patents

Abstract

PURPOSE:To surely take the matching at a resonance frequency and to suppress the radiation from the center conductor by making the thickness of a feeding part thinner than that of a part of the base formed with a radiation element. CONSTITUTION:A radiation element 23 is formed onto the surface of the base 21 and a ground conductor 22 is formed on the rear face. The surface of the base 21 is formed to be a smooth slope so that the part of the base formed with the radiation element 23 is thick and the part penetrated with the center conductor 25 of the coaxial line 24 is thin. A microstrip line 21 connects the radiation element 23 and the center conductor 25 on the base 21 to feed the radiation element 23. Thus, the reactive component of the input impedance of the microstrip antenna at the resonance frequency is reduced and the antenna and the external circuit are easily matched. Moreover, the spurious radiation due to the conductor 25 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a microstrip antenna used, for example, in the microwave band.

(Prior art) Generally, when feeding power to an antenna formed by forming a radiating element 12 on a substrate 11 with a ground conductor 1° on the back side as shown in FIG. A method of feeding power by passing through the center conductor 14 of the coaxial line 13 and directly connecting the center conductor 14 to the radiating element 12, or a fourth method.
As shown in the figure, a microstrip line 1 is placed on a substrate 11.
There is a method of forming a microstrip line 5 and connecting the center conductor 14 and the radiating element 12 through this microstrip line 15 to supply power. However, in either method, the connection between the board 11 and the external circuit must be made using a coaxial line, a connector, or the like. Therefore, if the thickness of the substrate 11 becomes thicker than the wavelength to a certain extent, the input impedance will increase at the antenna common frequency due to the influence of the center conductor 14 of the power feeding coaxial line 13 that passes through the substrate. Since it has a reactance component, it becomes necessary to supply power through a matching circuit. Furthermore, as shown in FIG. 5, radio waves are also radiated from this central conductor 14,
This will disturb the radiation pattern created by the

(Problems to be Solved by the Invention) As described above, in the conventional antenna feeding means, when a substrate with a thickness that cannot be ignored compared to the wavelength is used, the coaxial line passing through the substrate is The input impedance of the antenna increases due to the influence of the center conductor and the substrate, making matching at the resonant frequency difficult, and furthermore, radiation from the center conductor becomes a problem.

This invention was made to solve the above problems, and it is possible to ensure matching at the resonant frequency.
It is an object of the present invention to provide a microstrip antenna that can also suppress radiation from a center conductor.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a microstrip antenna according to the present invention includes a radiating element formed on a substrate, and a radiating element fed to the radiating element. Regarding the thickness, the feed point portion is configured to be thinner than the portion where the 11 radiation elements are formed.

(Function) In the microstrip antenna with the above configuration, the part where the feeding point is formed is thinner than the part where the radiating element is formed, so it is possible to reduce the influence of the center conductor of the feeding coaxial line, and thereby the antenna and Matching with external circuits becomes easier. Furthermore, since the feed point portion is thin, unnecessary radiation caused by the center conductor of the coaxial line can also be suppressed.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows its structure, where 21 is a substrate, 22 is a ground conductor formed on the back surface of the substrate 21, and 23 is a ground conductor formed on the back surface of the substrate 21. ) l element, 24 is a coaxial line, 25 is a center conductor, and 26 is a microstrip line. The substrate 21 is formed into a smooth slope shape on the surface side so that the portion where the radiating element 23 is formed is thick and the portion where the six central conductors 25 of the coaxial line 24 are formed is thin. The microstrip line 26 connects the radiating element 23 and the center conductor 25 on the substrate 21 and supplies power to the radiating element 24.
The width gradually becomes narrower toward the connection part.

In the microstrip antenna with the above configuration, the thickness of the substrate 21 becomes thinner as it goes from the forming part of the radiating element 23 to the connecting part between the microstrip line 26 and the center conductor 25, and gradually goes from the thicker part to the thinner part. Since the center conductor 25 and the radiating element 23 are connected through the microstrip line 26 by changing the thickness of the conductor 21, the input impedance and actance at the antenna resonant frequency can be reduced. This makes it easier to align with Furthermore, since the substrate in the portion through which the center conductor 24 passes is thin, unnecessary radiation caused by the center conductor 25 of the coaxial line 24 can also be suppressed.

In the above embodiment, the substrate is formed in a slope shape, but the same effect can be obtained even if the substrate is formed in a step shape. Moreover, as a method of feeding power to the microstrip line 2G, it is not necessary to feed power directly through a coaxial line as in the above embodiment, but as shown in FIG. Of course, it is also possible to do so. Furthermore, the present invention is also applicable to an array antenna using a microstrip antenna as a radiating element.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a microstrip antenna that can reliably achieve matching at the resonant frequency and can also suppress radiation from the center conductor.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of a microstrip antenna according to the present invention, FIG. 2 is a perspective view showing another embodiment according to the present invention, and FIGS. 3 and 4 are respectively conventional antenna feeding systems. FIG. 5, which is a diagram for explaining the means, is a diagram showing how unnecessary radio waves are generated by the conventional antenna power feeding means. 21... Substrate, 22... Ground conductor, 23... Radiation element, 24... Coaxial line, 25... Center conductor, 26...
...Microstrip line, coaxial connector.

Claims (1)

[Claims] 1. A microstrip antenna in which a radiating element is formed on a substrate and power is fed to the radiating element, characterized in that the thickness of the substrate is thinner at a feed point portion than at a portion where the radiating element is formed.