JPS6281103A - Microstrip antenna - Google Patents

Abstract

PURPOSE:To obtain a broad band microstrip antenna by arranging a conductor element in parallel with a radiation conductor element between the radiation element and a ground conductor plate, feeding the conductor element through a microstrip line and connecting the conductor element and the radiation through the feeder. CONSTITUTION:A radiation conductor element 1 made of a circular open type plane circuit is constituted to the 1st dielectric base 11 sufficiently thin in comparison with the wavelength by etching. A ground conductor plate 3 is provided to one side of the 2nd dielectric base sufficiently thin in comparison with the wavelength, and a circular conductor element 13 and a microstrip line 14 are constituted similarly to the radiation conductor element 1 on the other side by etching or the like and the conductor element 13 and the radiation conductor element 1 are connected through a feeder 15 at a feeding point 16. The conductor element 13 is connected to the radiation conductor element 1 through the feeder 15 and they are fed, then the conductor element 13 acts like a reactance compensation circuit element so as to attain a broad band of microstrip antenna.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microstrip antenna that operates with linearly polarized waves, and in particular to a microstrip antenna that aims to widen the band by providing a conductive element for the frequency characteristic of the impedance characteristic. Regarding.

[Conventional technology]

Microstrip antennas using unbalanced planar circuit resonators are generally small and el! Although it has many advantages such as a low profile and a low profile, it has the disadvantage that its frequency characteristics cannot be widened due to impedance characteristics.

FIG. 4 is a perspective view showing an example of a conventional circular microstrip antenna.

In the figure, (1) is a radiation conductor element made of a circular open planar circuit, (2) is a dielectric substrate (relative permittivity εr, thickness h) that is sufficiently thin compared to the wavelength, and (3) is a ground conductor. Board, (4)
is the radiation conductor element (1) from the microstrip line (5).
) is the power supply point that supplies power.

Next, the operation will be explained. Microstrip line (
5) and when power is supplied from the feeding point (4), radio waves are radiated from the open peripheral end (6), and in the example shown in FIG. 4, operate as linearly polarized waves.

The resonant frequency f of the fundamental mode of this resonator is.

The band BW of a microstrip antenna is generally
Since nw=(S-1)/QJT-(s is the standing wave ratio), the band BW is determined by qW. Here, the Q ratio of the microstrip antenna is proportional to ε of the dielectric substrate (2) and inversely proportional to the thickness of the substrate IIK. When the dielectric constant e1 of the vj electric substrate (2) increases, energy is trapped inside the circular microstrip antenna, the Q value increases, and the radiation efficiency decreases. Therefore, in order to increase the radiation efficiency and widen the @ region, it is known to use a low am ratio substrate and increase the substrate thickness. By the way, when microstrip antennas are made to have a wider band by increasing the thickness of the substrate or lowering the dielectric constant as in the past, the power radiated from the microstrip line (5) increases. If you want to obtain linearly polarized waves.

This causes inconveniences such as deterioration of directivity and the like.

Furthermore, in public sector communications, etc., bidirectional communication is common, and the required bandwidth is usually 896% to 15%. However, even if the equivalent dielectric constant is lowered to about 1.1 to 1.3 by increasing the thickness of the substrate or by using a honeycomb substrate, etc., to achieve a wider band, the standing wave ratio will still be low over the required band of 8% or more. A characteristic of 1.5 or less has not been obtained.

[Problem that the invention seeks to solve]

Conventional microstrip antennas have I
ll has been revised, so in order to use it as an antenna that operates with @-line polarization over a desired band of 896 or more, such as on a public street 1st grade, it is necessary to have practical problems such as deterioration of 9 reflection characteristics in terms of frequency characteristics of impedance characteristics. There was a problem. In addition, the thickness of the substrate must be increased, which increases the radiation power from the microstrip line, resulting in problems such as deterioration of characteristics such as directivity. This was developed to solve these problems, and it is possible to lower the reflection characteristics even if the desired band is 896 or more.

The purpose of this invention is to obtain a linearly polarized microstrip antenna that can suppress the radiation power from an IJ tube line to a low level.

[Means for solving problems]

A microstrip antenna according to the present invention.

A conductor element parallel to the radiation conductor element is arranged between the radiation conductor element and the ground conductor plate, power is supplied to the conductor element by a microstrip line, and the conductor element and the radiation conductor element are connected by a feeder line.

[°action]

A microstrip antenna according to the present invention.

The conductive element acts as an actance compensation circuit element, and even if the desired band is 896 or more, the reflection characteristics can be lowered, and the microstrip antenna can have a wider band.

Furthermore, since the microstrip line can be selected for Mj of the radiation conductor element and the ground conductor plate, the effective substrate thickness of the microstrip line can be reduced.

The radiated power from the microstrip line can be kept low.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
Figures (a) and (bl) are views showing one embodiment of the present invention, in which Figure 1 (example) shows a perspective view, and Figure 1 (b) shows a sectional view.

In the figure, +11. +31 and (61 are exactly the same as an example of the conventional circular microstrip antenna shown in FIG. 4, and (111 is the first dielectric base &(relative dielectric constant ε, 1. The radiation conductor element +11 is constructed by etching etc. using a circular open planar circuit with a thickness of . h2
), two ground conductor plates (3) are provided on the - side, and nine circular conductor elements α are provided on the radiation conductor element (1) side on the other side.
J and the microstrip line I are similarly constructed by etching, etc., and the power supply, 11i! The conductor element 0 and the radiation conductor element (!) are connected by Q5 at the feed point aθ, the first dielectric substrate (111) and the second dielectric substrate (13 are bonded together by appropriate means). , in one embodiment, the relative permittivity εr1t εr2 is set as 2.2, and the thickness is set as h1+h2: 0.07λ0 (λ0 is the free space wavelength at the center frequency), and the thickness h2 is the radiation from the microstrip line. As appropriate, so as to suppress the power consumption,
An example of using a thinner setting is shown.

(Micros according to this invention configured as described above)
The operation of one embodiment of the IJ tube antenna will be described.

FIG. 2 is a diagram for explaining the operation of the microstrip antenna according to the present invention, and FIG.
In the figure showing an example of the microstrip antenna according to the present invention shown in bl.

The effect of the distance d by which the feeding point ae is offset in the radial direction of the linearly polarized wave from the open peripheral end (6) of the radiation conductor element +11 is shown on the Smith chart when the conductor element a3 is not loaded. Above, the distance d is the radiation conductor element (1)
The frequency characteristic of the impedance characteristic decreases as it approaches the center of It was experimentally found that the effect was similar.

FIG. 3 is a diagram for explaining the operation of the microstrip antenna according to the present invention.
In the drawings showing an embodiment of the present invention shown in FIGS. 6 and 6(b), the feeding point I is appropriately set and the effect of conductive element 0 is shown on the Smith chart.

(a) shows the characteristics of a microstrip antenna not loaded with conductive element a3, and (b) shows the characteristics of a microstrip antenna with conductive element a3 loaded.If you compare these, it is clear that conductive element 0 is used. By connecting and supplying power to the radiation conductor element (1) via the electric wire α, the conductor element a3 acts as an actance compensation circuit element,
This allows the microstrip antenna to have a wider band, and a standing wave ratio of 1.5 or less has been experimentally obtained over a 13% band.

In addition, conventionally, the microstrip line I was connected to a radiating conductor element (
1) and (1) were constructed on one plane, but according to the present invention, the microstrip line I can be arranged on the 20th dielectric substrate α2, so the effective substrate length constituting the microstrip line α is reduced. The thickness of the microstrip line 0 can be made thinner, and the power radiated from the microstrip line 0 can be kept low.

Although the conductive element 0 is shown as circular in the embodiment, it is not limited to a particular shape, and may be of any shape, such as a rectangle or a square, which acts as a reactance compensation circuit element.

In addition, in the above embodiment, the conductor element αj was explained as one piece, but in addition to the conductor element 0, an air layer or a dielectric layer is interposed between the conductor element a3 and the radiating conductor element +11 to create an excessive interval. It is presumed that the effect of the above embodiment can be further improved by loading a plurality of them in parallel.

In the above embodiment, the thickness of the electric body is 0.07λ. .

Although the relative dielectric constant was set to 2.2, it is not particularly limited (
Similar effects can also be obtained by using a honeycomb substrate or the like as the dielectric substrate.

Furthermore, in the above embodiment, the case of a nine-circular radiation conductor element was described, but the same effect can be obtained with an oval radiation conductor element.

〔Effect of the invention〕

As described above, according to the present invention, the conductor element is arranged in parallel between the radiation conductor element and the ground conductor plate, and power is supplied to the conductor element by the microstrip line.

Since the conductor element and the radiation conductor element are connected by a feeder line, it is possible to expand the band without losing the advantages of being small, lightweight, and low profile. You can get something.

Further, there is an effect that linearly polarized wave operation with stable characteristics such as directivity characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 (al and (bl) are diagrams showing one embodiment of the present invention. Figures 2 and 3 are diagrams for explaining the operation of one embodiment of the present invention using Smith charts, and Figure 4 is a conventional diagram. 1 is a perspective view showing an example of a circular microstrip antenna. In the figure, (1) is a radiation conductor element, (31 is a ground conductor plate, (6) is an open peripheral end, all is a first dielectric substrate, is the second dielectric substrate, (13 is the conductive element, (1
41 is Micros) IJ Tsubu line, a! 3 is the power supply line,
ae is a power feeding point. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A microstrip antenna configured by providing a circular or oval open planar circuit radiation conductor element on a dielectric substrate thinner than the wavelength, and feeding power to the radiation conductor element by a microstrip line, A conductor element parallel to the radiation conductor element is arranged between the radiation conductor element and the ground conductor plate, power is supplied to the conductor element by a microstrip line, and the conductor element and the radiation conductor element are connected by a feed line. microstrip antenna. (2) In addition to the conductor element parallel to the radiation conductor element, one or more conductor elements are arranged with an air layer or a dielectric layer in between.
Microstrip antenna as described in section.