JPH05191131A - Microstrip antenna - Google Patents

Abstract

PURPOSE:To utilize a microstrip antenna for linear polarization as that for circular polarization. CONSTITUTION:The two sides opposed to a cublic radiating electrode 11 are covered with dielectric films 12, and the degeneration of a mode is separated so as to receive circularly polarized waves. When it is adapted to the microstrip antenna forming a rectangular electrode for circular polarization, the trough (band) of a returning loss characteristic can be made wide or narrow, and the characteristic can be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a microstrip antenna used in a navigation system or the like, and more particularly to a microstrip antenna capable of transmitting / receiving circularly polarized waves.

[0002]

2. Description of the Related Art In a GPS navigation system or the like, a small antenna for receiving a signal from a satellite is required, and use of a microstrip antenna is considered as one of them.

In this microstrip antenna, a radiation electrode having a size of a half of the wavelength of light received is provided on the surface of a dielectric substrate, and a ground electrode is formed on the entire back surface. There are square and circular radiating electrodes, and by devising their shape, the receiving frequency can be broadened.

Since signals such as GPS signals from satellites use circularly polarized waves, a structure is considered in which microstrip antennas can also receive such circularly polarized waves. In order to use the microstrip antenna for circular polarization, a structure provided with a degenerate separation element is considered.

FIG. 5 shows an example of a rectangular microstrip antenna having such a degenerate separation structure, in which a notch 55 is formed at the corner of the radiation electrode 51 on the surface of the dielectric substrate 50. As a result, the return loss characteristic shown in FIG. 4A has a band as shown in FIG. 4B, and circular polarization reception becomes possible. In addition, in the circular radiation electrode, the degenerate separation structure is obtained by the protrusion and the notch.

[0006]

When forming an electrode for circularly polarized waves as described above, pattern accuracy of the electrode is required. Particularly, when a substrate having a high dielectric constant is used, the dimensional accuracy of the electrodes has a great influence. When forming electrodes by printing, it is very difficult to obtain strict accuracy.

Moreover, it is difficult to obtain desired characteristics due to variations in the dielectric material of the substrate and variations in the electrode precision. In order to correct this and match it with a predetermined characteristic, it was necessary to remove part of the electrode pattern.

The present invention solves such problems and provides a microstrip antenna capable of circularly polarized wave reception with a simple structure and manufacturing method.

[0009]

The present invention solves the above-mentioned problems by partially forming a dielectric film on the substrate and the surface of the radiation electrode to enable degenerate separation.

That is, in a microstrip antenna in which a rectangular radiation electrode is provided on the front surface of a dielectric substrate and a ground electrode is provided on the entire back surface, from the end faces of the dielectric substrate facing the center of the substrate to the radiation electrode. It is characterized in that it has a dielectric film which extends and whose side on the center side of the substrate is parallel to the side of the radiation electrode.

[0011]

[Function] The dielectric film separates the mode degeneracy, the return loss characteristics can be adjusted, and circularly polarized waves can be received.

It is also possible to adjust the return loss characteristic of the circularly polarized microstrip antenna, that is, to adjust the band to be widened or narrowed.

[0013]

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

FIG. 1 is a plan view showing an embodiment of the present invention. A radiation electrode in which a thick film paste of copper is printed and baked on the surface of a dielectric substrate 10 having a dielectric constant of about 20 and plated with gold.
11 is formed. Dielectric films 12 are formed on opposite sides of the dielectric substrate 10, respectively. The dielectric film 12 is formed so as to extend from the end face portion of the substrate to above the radiation electrode 11, and the side on the center side is formed to be parallel to the side of the radiation electrode.

A Mg-Ca-Ti-based ceramic fired substrate having a dielectric constant of 21 was molded into a 25 mm square and a thickness of 6 mm, and a 20 mm square radiation electrode was formed on the surface. A 25 mm square ground electrode was formed on the entire back surface. As a result, a 1.6 GHz band single point back-feed microstrip antenna was formed.

A dielectric film having a width of 5 mm was formed inward from the side facing the surface of the dielectric substrate. A dielectric paste having a dielectric constant of 10 was used by mixing this dielectric ceramic and resin. That is, the dielectric paste was formed on the radiation electrode by 2.5 mm.

The microstrip antenna having the above structure has a return loss characteristic before application of the dielectric paste as shown in FIG.
What was only the peak of 1.6 GHz like (a) of
After applying the dielectric paste, 1.59 as shown in Fig. 2 (b).
A peak appeared at GHz and showed an attenuation characteristic of 15 dB or more up to 1.6 GHz.

As described above, the addition of the dielectric film separates the degeneracy, and a microstrip antenna for circular polarized wave having satisfactory return loss characteristics can be obtained. With such a structure, degenerate separation is possible even with a microstrip antenna having a square electrode, and a linearly polarized microstrip antenna can be used for circularly polarized waves.

In the GPS, the band is used only about 2 MHz, and even in the design of the return loss characteristic, a very small degenerate separation is sufficient. According to the present invention, the degree of degeneracy separation can be controlled by the coating amount.

The present invention can be used not only for the case of using the linearly polarized wave for the circularly polarized wave but also for the adjustment of the return loss characteristic for the circularly polarized wave. FIG. 3A shows a circularly polarized wave in which a rectangular radiation electrode 31 is formed on the dielectric substrate 30, but a dielectric film 32 is formed on the short side. In this case, the valley in the return loss characteristic can be widened.

Further, as shown in FIG. 3B, if the dielectric film 42 is formed on the long side of the radiation electrode 41, the valley of the return loss characteristic can be narrowed.

[0022]

According to the present invention, by degenerate separation, the microstrip antenna for linearly polarized waves can be used for circularly polarized waves, and the return loss characteristics can be arbitrarily set by the method of forming the dielectric film. can do.

Further, it is possible to match variations in the characteristics of the circularly polarized microstrip antenna with the dielectric film, and it is possible to easily obtain a microstrip antenna having desired characteristics.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the return loss characteristic.

FIG. 3 is a plan view of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of the return loss characteristic of the antenna.

FIG. 5 is a plan view of a conventional example.

[Explanation of symbols]

 10, 30, 40, 50: Dielectric substrate 11, 31, 41, 51: Radiating electrode 12, 32, 42: Dielectric film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyoshi Takano 828 Hinohara, Tamagawa, Hamahara, Hiki-gun, Saitama Prefecture Toko Co., Ltd. Tamagawa factory

Claims (4)

[Claims] 1. A microstrip antenna having a rectangular radiation electrode on the front surface of a dielectric substrate and a ground electrode on the entire back surface of the dielectric substrate, from the opposing end faces of the dielectric substrate to the center of the substrate, respectively, up to the radiation electrode. A microstrip antenna characterized by comprising a dielectric film which extends and whose side on the center side of the substrate is parallel to the side of the radiation electrode. 2. The microstrip antenna according to claim 1, wherein the radiation electrode has a square shape, and has a dielectric film extending from the opposite two sides onto the radiation electrode. 3. The microstrip antenna according to claim 1, wherein the radiation electrode has a rectangular shape, and the radiation electrode has a dielectric film extending from the end face of the dielectric substrate on the short side thereof onto the radiation electrode. 4. The microstrip antenna according to claim 1, wherein the radiation electrode has a rectangular shape, and the radiation electrode has a dielectric film extending from the end surface of the dielectric substrate on the long side thereof onto the radiation electrode.