JPH0219005A - Short-circuited microstrip antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a one-end short-circuit type microstrip antenna that is fed by a coaxial line, and in particular, by using a metal rod as the short-circuiting method, the resonant frequency of the radiating conductor element can be adjusted. [Prior art] A short-circuited microstrip antenna using an unbalanced planar circuit resonator generally has the advantages of being small, lightweight, and low loss. .

Figures 3 (a) and (b) are 0. For example, Haneishi, Suga "Single-sided short-circuit type microstrip antenna" 1985 IEICE General Conference (S 9-5) 3-275 to 3-
276 is a diagram showing an example of the conventional one-end short-circuit type microstrip antenna shown on page 276. FIG. Figure 3 (a
) is a plan view, and FIG. 3(b) is a sectional view.

In the figure, (1) is a radiation conductor element made of a rectangular one-end short-circuited planar circuit with side lengths a and b, and (2) is a dielectric substrate that is sufficiently thin compared to the wavelength (relative permittivity gr, thickness h), +31 is the ground conductor plate, (4) is the coaxial line of the input terminal, (6) is the center conductor of the coaxial line, (5) is the center conductor of the coaxial line (4) (
6) is the feed point that connects to the radiation conductor element (1), (7) is the open peripheral end from which radio waves are radiated, and (8) is the radiation conductor element +1
1 to the ground conductor plate (3).

Next, the operating principle will be explained. When microwaves are fed from the feeding point (5), radio waves are radiated from the open peripheral end (7). The example shown in FIGS. 3(a) and 3(b) operates as a linearly polarized wave.

The fundamental mode resonant frequency fo of this one-end short-circuited microstrip antenna is determined mainly by the side length a of the radiation conductor element (1) and the relative dielectric constant tr of the dielectric substrate (2). Also, one frequency bandwidth is mainly the dielectric substrate + 2
It is determined from the dielectric constant My of 1 and the thickness h4C, 6
The smaller 1 and the larger h, the wider the band, but there is a limit to the selection range of the thickness h in order to prevent the generation of higher-order modes.

The frequency band of the one-end short-circuited microstrip antenna that has been put into practical use is approximately several inches, as shown in FIG.

The feed point impedance is the feed point (5) at the open peripheral end (
7), the impedance becomes high when c = O, and the impedance of the feeding point gradually decreases as the feeding point (5) approaches the short-circuit peripheral end (8) of the radiation conductor element (1). Dimension C is selected so as to achieve impedance matching with the coaxial line (4), and 1 dimension d is set to d=b/2 in order to prevent generation of cross-polarized components6 [Problem to be solved by the invention] Conventional short-circuited micros
Dimensions of short-circuited microstrip antenna from the perspective of cross-polarization suppression and resonant frequency.

Since the shape and the location of the coaxial line are limited, when molding and using a large number of short-circuited microstrip antennas, the electrical characteristics of each microstrip antenna will depend on variations in the permittivity of the dielectric substrate used and workability. There were issues such as differences depending on the tolerance of the

Furthermore, since the conventional one-end short-circuited microstrip antenna essentially has a narrow band, it has had problems such as difficulty in matching resonance frequencies.

This invention was made to solve the above-mentioned problems, and it is possible to eliminate variations in the dielectric constant of the dielectric substrate and workability tolerances without changing the dimensions and shape of the radiation conductor element or coaxial line. The object of the present invention is to obtain a short-circuited microstrip antenna that enables matching of electrical characteristics such as extended wave number matching and impedance matching even when the antenna is added.

[Means to solve the problem]

In the one-end short-circuit type microstrip antenna according to the present invention, instead of the short-circuit peripheral end (81) connecting between the radiation conductor element (1) and the ground conductor plate (3), a plurality of short-circuit peripheral ends (8) are arranged at arbitrary intervals. The idea is to arrange several metal rods, and change the resonant frequency of the one-end short-circuited microstrip antenna by adjusting the spacing and number of the metal rods to match the desired frequency.

[Effect]

The one-end short-circuit type microstrip antenna of the present invention short-circuits the radiation conductor element (1) and the ground conductor plate (3) with a plurality of metal bars on the opposite side of the open peripheral end (7),
By changing the power and spacing of the metal rods, one end short-circuit type microstrip can be achieved without changing the side length a of the radiation conductor element (1) or the relative dielectric constant B of the dielectric substrate (b). The resonant frequency of the antenna can be matched to a desired frequency.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1(a), (b), and (C) are views showing one embodiment of the present invention, FIG. 1(a) is a plan view, and FIG. 1(b) is a plan view.
is a sectional view, and FIG. 1(c) is a diagram showing an equivalent circuit. In the figure.

(1) to (81) are exactly the same as the conventional one-end short-circuited microstrip antenna. (9) is.

The conventional short-circuited microstrip antenna (81
Instead of connecting the entire surface to the ground conductor plate at the short-circuited peripheral end of the wire, holes are made at 6 intervals (e) using metal rods for connecting to the ground conductor plate.

FIG. 2 is a diagram showing changes in the resonant frequency of the short-circuited microstrip antenna when the number of metal rods (9) is changed.

The operation of one embodiment of the one-end short-circuit type microstrip antenna according to the present invention configured as described above will be described.

The high frequency signal input to the coaxial line (4) of the input terminal is
The feed point (5) is excited via the center conductor (6), and linearly polarized radio waves are radiated from the open peripheral end (7) of the radiation conductor element tl+. Feeding point (5) for the radiation conductor element (1)
) is determined from the viewpoint of impedance matching and cross-polarization suppression, similar to the conventional short-circuited microstrip antenna. On the other hand, the resonant frequency To of the short-circuited microstrip antenna is as follows.

Without changing the side length a of the radiation conductor element (1) and the relative dielectric constant tl of the dielectric substrate (21), a distance e is set at the short-circuit peripheral end (8).
It can be set arbitrarily using a plurality of metal rods (9).

When the number of metal screws (9) is increased and the interval e is narrowed, the side length a of the radiation conductor element (1) becomes equivalently shorter, and the resonant frequency moves to a higher frequency as shown by the dotted line in Figure 2. However, if the number of metal rods (9) is reduced and the interval e is increased, the side length a of the radiation conductor element tl+ becomes equivalently longer, and the resonant frequency shifts to a lower frequency as shown by the dotted line in Figure 2. The resonant frequency can be varied.

In the above embodiment, the metal rod (9) is shown as a circle, but it may be formed as a square. In addition, in the above embodiment, the explanation was given using +21 ft-1 dielectric substrate between the radiation conductor element (1) and the ground conductor plate (3), but it may be configured with a plurality of dielectric substrates, and the above-mentioned Effects similar to those of the embodiment can be obtained.

Further, in the above embodiment, the shape of the one-end short-circuited microstrip antenna was explained using a rectangular radiating conductor element +11, but the same effect can be obtained with a square 0 circular or arbitrary-shaped radiating conductor element +11.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of metal screws (9
) at the short-circuit peripheral edge (8), and by changing the number and spacing of the metal bars (9), the side length a of the radiation conductor element (1) and the relative dielectric constant 6r of the dielectric substrate (2) can be adjusted. Since the resonant frequency can be changed without changing the resonant frequency, variations in the dielectric constant of the dielectric substrate are due to tolerances in workmanship, and even if the resonant frequency changes, the number of metal rods (9) does not change. By changing the spacing, it is possible to obtain a one-end short-circuited micros l-IJ tube antenna that can be matched to a desired resonant frequency.

[Brief Description of the Drawings] Figures 1 (a), (b), and (c) are diagrams showing one embodiment of the present invention, and Figure 2 is an example of a case where the number and spacing of metal bars are changed. Figure 3 shows an example of a conventional one-end short-circuited microstrip antenna; Figure 4 shows a conventional one-end short-circuited microstrip antenna. FIG. 3 is a diagram showing the characteristics of resonance frequency and reflection loss. In the figure, (1) is a radiation conductor element, (2) is a dielectric substrate, (
3) is the ground conductor plate, (4) is the coaxial line, A5) is the feed point, (6) is the center conductor, (7) is the open peripheral edge, (8) is the shorted peripheral edge, (9) is the metal It's a stick. Note that in FIG. 8, the same reference numerals indicate the same or equivalent parts. Figure 1: Kano 10) 2 Kankan body ↓ 藷, 3 aru ↓ body board

Claims (1)

[Claims] A radiation conductor element with a plane circuit short-circuited at one end to a grounded conductor plate is provided on a dielectric substrate that is thinner than the wavelength, and a coaxial line for power supply is provided on the back of the opposing grounded conductor plate. A short-circuit type microstrip antenna, characterized in that the resonant frequency of the microstrip antenna is made variable by the number and spacing of metal bars used to short-circuit between the ground conductor plate and the planar circuit. antenna.