JPH0646682B2 - Short-circuited microstrip antenna - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a microstrip antenna with one end short-circuited that is fed by a coaxial line. The present invention relates to a structure in which the resonance frequency can be changed arbitrarily.

[Conventional technology]

Microstrip antennas with short-circuited ends that use unbalanced planar circuit resonators generally have the advantages of small size, light weight, and low loss.

Figures 3 (a) and (b) are shown, for example, on pages 3-275 to 3-276 of the IEICE General National Conference (S9-5), "Semiconductor strip with one-side short-circuited type", Saga, Hagaishi, Suga. FIG. 6 is a diagram showing an example of a conventional short-circuited one-end type microstrip antenna. Figure 3 (a) is a plan view, 3rd
Figure (b) is a sectional view. In the figure, (1) is a radiating conductor element by a rectangular one-sided short-circuit type planar circuit with side lengths a and b, (2) is a dielectric substrate (relative permittivity ε _r , thickness h) sufficiently thin compared to the wavelength,
(3) 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 (6) of the coaxial line (4), and the radiating conductor element (1) (7) is the open peripheral edge where radio waves are radiated, (8) is the radiating conductor element (1) and the ground conductor plate (3)
It is the peripheral edge of the short circuit connected to.

Next, the operation principle will be described.

When microwave is fed from the feeding point (5), the open peripheral edge (7)
More radio waves are emitted. In the example shown in FIGS. 3 (a) and 3 (b), it operates as a linearly polarized wave.

The resonance frequency ₀ of the fundamental mode of this one-short-circuited microstrip antenna is mainly determined by the side length a of the radiating conductor element (1) and the relative permittivity ε _r of the dielectric substrate (2). The frequency bandwidth is primarily determined by the dielectric constant epsilon _r and the thickness h of the dielectric substrate (2), the epsilon _r small city,
The larger h is, the wider the band becomes, but the range of thickness h is limited to prevent the generation of higher-order modes. The frequency band is about several percent as shown in FIG.

The feeding point impedance becomes high impedance when the feeding point (5) matches the open peripheral end (7) and c = 0, and the feeding point (5) is short-circuited peripheral end (8) of the radiating conductor element (1). ), The feeding point impedance gradually decreases as it gets closer to), and dimension c is selected so as to achieve impedance matching with the coaxial line (4). Further, the dimension d is set to d = b / 2 in order to prevent the generation of cross polarization components.

[Problems to be Solved by the Invention]

Since the conventional short-circuited microstrip antenna is configured as described above, from the viewpoint of impedance matching, cross polarization suppression and resonance frequency, the size, shape and coaxial line of the short-circuited microstrip antenna are Since the positions are limited, when manufacturing and using a large number of short-circuited microstrip antennas, the electrical characteristics of each differ depending on the variation of the dielectric constant of the dielectric substrate used and the tolerance of workability. There was such a problem.

In addition, the conventional one-side short-circuit type microstrip antenna has a problem that it is difficult to match the resonance frequency because the band is essentially narrow.

The present invention has been made in order to solve the above problems, and it is possible to reduce the variation in permittivity of dielectric substrates and the tolerance of workability without changing the size and shape of the position and the like of the radiation conductor element and the coaxial line. The objective is to obtain a microstrip antenna with one-end short circuit that can match electrical characteristics such as resonance frequency matching and impedance matching even if added.

[Means for Solving the Problem] The short-circuited microstrip antenna according to the present invention has a short-circuiting peripheral end (8) instead of a radiating conductor element (1) and a grounding conductor plate (3). A plurality of through-hole platings are arranged on the short-circuited peripheral edge (8) side at arbitrary intervals, and the resonance frequency of this short-circuiting type microstrip antenna is varied according to the spacing and the number of the through-hole platings. It is designed to match the desired frequency.

[Action]

The short-circuited type microstrip antenna according to the present invention has an open peripheral end between the radiation conductor element (1) and the ground conductor plate (3).
By short-circuiting with a plurality of through-hole plating on the side opposite to (7), and changing the number and spacing of the through-hole plating, the side length a of the radiating conductor element (1) or the dielectric substrate
The resonance frequency of the one-side short-circuit type microstrip antenna can be matched to a desired frequency without changing the relative permittivity ε _r of (2).

〔Example〕

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

1 (a), (b) and (c) are views showing an embodiment of the present invention, wherein FIG. 1 (a) is a plan view, FIG. 1 (b) is a cross sectional view, and FIG.
FIG. (C) is a diagram showing an equivalent circuit. In the figure, (1) to (8)
Is exactly the same as the conventional short-circuited microstrip antenna described above. (9) is for connecting a grounding conductor plate by making a hole at an interval e instead of connecting the conventional one-sided short-circuit type microstrip antenna to the grounding conductor plate on the entire surface at the short-circuited peripheral edge (8). It is a through hole.

FIG. 2 (a) is a diagram showing changes in the resonance frequency of the one-side short-circuit type microstrip antenna when the number of through-hole platings (9) is changed.

The operation of one embodiment of the one-short-circuited 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 excites the feeding point (5) via the central conductor (6), and the radiating conductor element
Radio waves of linear polarization are radiated from the open peripheral edge (7) of (1).
The position of the feeding point (5) with respect to the radiating conductor element (1) is determined from the viewpoint of impedance matching and cross polarization suppression, as in the conventional short-circuited microstrip antenna. On the other hand, the resonance frequency ₀ of the short-circuited microstrip antenna does not change the side length a of the radiating conductor element (1) and the relative permittivity ε _r of the dielectric substrate (2) without changing the short-circuit peripheral end (8 ) To interval e
It can be set arbitrarily with a plurality of through-hole plating (9) provided in. Increase the number of through hole mates (9) to increase the spacing e
When the width is narrowed, the side length a of the radiating conductor element (1) is shortened equivalently, and the resonance frequency moves to a higher frequency as shown by the dashed line in Fig. 2 (a), and the through hole plating (9) When the number is decreased and the distance e is increased, the side length a of the radiating conductor element (1) becomes equivalently long, and the resonance frequency moves to a lower frequency as shown by the points in Fig. 2 (a). The frequency can be changed.

The details of the relationship between the number and spacing of through-hole plating and the resonance frequency are shown below.

FIG. 2 (b) shows an equivalent circuit showing the average value of the current length of the microstrip antenna with short-circuited ends.

When microwaves are fed from the feeding point, they flow to the open peripheral end side and the short-circuited peripheral end, respectively, and radio waves are radiated from the open peripheral end.

Here, the average value of the length of the current flowing at the open peripheral edge is
₁ and the average value of the length of the current flowing around the short-circuited peripheral end is ₂ .

The side length a of the short-circuited microstrip antenna is
₁ + ₂ .

Next, the flow of current will be shown with reference to FIGS. 2 (c) and 2 (d).

FIG. 2 shows the case where the through hole plating is almost entirely on the peripheral edge of the short circuit. As a current flow from the feeding point to the open peripheral end, currents having different lengths from _1a to ₁ flow, and the average value of the current lengths can be obtained by the following equation. ₁ = ( _1a + _1b + _1c + ... + ₁ ) / K (1) On the other hand, the length ₂ of the current to the short-circuit peripheral edge is ₂ = ( _2a + _2b + ... + _2j ) / j
…… (2) can be obtained.

Therefore, the side length α is α = ₁ + ₂ (3) Next, the case where through-hole plating is sparse at the peripheral edge of the short circuit is shown.

As shown in FIG. 2 (d), when the number of through-hole plating is reduced from 10 in FIG. 2 (b) to 6, for example, the length of the current flowing from the feeding point is as follows. Become.

The length ₁ to the open peripheral edge does not change.

A length of ₂ up to the peripheral edge of the short circuit directly flows into the through-hole plating, and flows into the through-hole plating while passing through between the through-hole plating.
The longer it goes around, the longer it becomes.

That is, ₂ < ₂ ′ = ( _2a ′ + _2b + _2c ′ + _2d
+ _2e '+ _2f + _2g + _2h ' + _2i +
_2j ) / j (4) However, _2a '> _2a , _2c '> _2c , _2e '> _2e , _2h '> _2h Therefore, the side length a is a = ₁ + ₂ '... (5), and the side is The length a becomes longer.

The length of the side length a is closely connected to the resonance frequency of the short-circuit microstrip antenna with one end, and can be roughly calculated by the following equation.

C: speed of light, ₀ : resonance frequency ε _r : relative permittivity of the dielectric substrate h: thickness of the dielectric substrate Note that equations (6) and (7) are described in, for example, IJ Bahl, P. Bhartia “Microstrip Antennas”. 1982 Published by Artech House 31
The design formulas for the microstrip antennas shown on pages 66 to 66 are replaced with the design formulas for the microstrip antenna with a short-circuited end.

Here, the side length a is equivalently increased, or the through hole interval is reduced to be equivalently shortened.
The resonance frequency can be changed as shown in (e).

In the above embodiment, the through hole plating (9) is shown as a circle, but it may be formed as a square. Further, in the above embodiment, the one dielectric substrate (2) is described between the radiation conductor element (1) and the ground conductor plate (3), but it may be composed of a plurality of dielectric substrates. The same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the shape of the one-side short-circuit type microstrip antenna is explained as the case of the rectangular radiating conductor element (1), but the same effect can be obtained even if the radiating conductor element (1) is square, circular or of any shape. Is obtained.

〔The invention's effect〕

As described above, according to the present invention, by arranging a plurality of through-hole mates (9) at the peripheral edge (8) of the short circuit and changing the number and spacing of the through-hole mates (9), the radiation conductor element can be changed.
Since the resonance frequency can be changed without changing the side length a of (1) and the relative permittivity ε _r of the dielectric substrate (2), variations in the relative permittivity of the dielectric substrate and tolerance of workability Due to
Even if the resonance frequency changes, by changing the number and spacing of the through-hole plating (9), it is possible to obtain the one-side short-circuit type microstrip antenna that can achieve matching with the desired resonance frequency.

[Brief description of drawings]

1 (a), (b) and (c) are views for explaining one embodiment of the present invention, and FIGS. 2 (a), (b), (c), (d) and (e). Is a diagram for explaining the relationship between the number of through-hole plating, the interval and the resonance frequency. FIGS. 3 (a) and 3 (b) are diagrams showing an example of a conventional one-side short-circuit type microstrip antenna, FIG. FIG. 6 is a diagram showing characteristics of a resonance frequency and a reflection loss of a conventional one-short-circuited type microstrip antenna. In the figure, (1) is a radiating conductor element, (2) is a dielectric substrate, (3) is a ground conductor plate, (4) is a coaxial line, (5) is a feeding point, (6) is a central conductor, and (7) ) Is an open peripheral edge, (8) is a short-circuited peripheral edge, and (9) is a through hole plating. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A dielectric substrate thinner than a wavelength, a ground conductor plate provided on one surface of the dielectric substrate, and a rectangle having side lengths a and b provided on the other surface of the dielectric substrate. None, and one end having a side length b is a radiating conductor element by a planar circuit having one end short-circuited to the grounding conductor plate, and a radiating conductor element provided on the back surface of the grounding conductor plate for feeding power to the radiating conductor element via a center conductor. In a short-circuited one-end type microstrip antenna including a coaxial line, through-hole plating used for short-circuiting between the radiation conductor element and the ground conductor plate is provided along a side length b direction at a short-circuited peripheral end of the radiation conductor element. By changing the side length a of the radiating conductor element or the relative permittivity of the dielectric substrate by setting the number and spacing of the through-hole plating according to the resonance frequency of the microstrip antenna. One end short-circuited microstrip antenna and sets the frequency of the microstrip antenna to a desired frequency without.