JPH0758539A - Microstrip antenna - Google Patents

Abstract

PURPOSE:To make the microstrip antenna for a portable equipment small and to attain broad band by loading a parasitic element and lumped constant components. CONSTITUTION:A parasitic element 15 is coupled with a non-radiation end 14a of a feeding element 14 and other parasitic elements 16, 17 are coupled with radiation ends 14b, 14c, 15b, 15c of the feeding element 14 and the parasitic element 15. Lumped constant components 18 are loaded between the feeding element 14 and the parasitic element 16, or between the feeding element 14 and the parasitic element 15 or between the parasitic elements 15, 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and wide band microstrip antenna for portable devices.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view showing an example of a conventional wideband microstrip antenna. In FIG. 4, 1
Is a ground plane of the antenna, 2 is a dielectric substrate, 3 is a feeding element, 4 is a feeding point, and 5 is a parasitic element. in this way,
In the conventional microstrip antenna, the band width of the microstrip antenna is increased by using the parasitic element 5.

FIG. 5 is a sectional view showing another example of a conventional wideband microstrip antenna. In FIG. 5, 6
Is a ground plane of the antenna, 7 is a dielectric substrate, 8 is a feeding element, 9 is a feeding point, and 10 is a parasitic element. Also in this example, the parasitic element 10 is used to widen the band of the microstrip antenna.

[0004]

However, in the conventional example shown in FIG. 4, since a large number of parasitic elements 5 are loaded, there is a problem that the antenna becomes large. Also,
Since the number of the parasitic elements 5 is large, there is a problem that the radiation pattern of the antenna changes depending on the frequency. (Reference: Girish Kumar and Kuldip C. Gupta: “N
onradiating Edges and Four Edges Gap- Coupl
ed Multiple Resonator Broad- Band Microstri
p Antennas "IEEE Trans. Antennas Propaga
t., vol. Ap-33, pp 173-178, Feb. 198
5. )

On the other hand, in the conventional example shown in FIG. 5, since the parasitic element 10 and the feeder element 8 are on different dielectric substrates 7,
There was a problem that the antenna became thick. There is also a problem in that the cost of the antenna also increases.

The present invention solves the above-mentioned conventional problems, and provides an excellent microstrip antenna which can realize a wide band and can be miniaturized with almost no deterioration in antenna characteristics. The purpose is to

[0007]

In order to achieve the above object, the present invention is one in which a parasitic element is coupled to one non-radiating end and both radiating ends of a feeding element of a microstrip antenna. Also, a lumped constant component is loaded between the feeding element and the parasitic element or between a plurality of parasitic elements.

[0008]

With the above structure, the present invention makes it possible to cause multiple resonance in the antenna by using a parasitic element having substantially the same size as the feeding element at one non-radiating end of the feeding element. Further, by loading a lumped constant component between the parasitic element at the radiating end and the feeder element, the band can be widened even if the number of the parasitic elements is small. Further, by loading the parasitic elements on the radiating ends on both sides of the feeding element and the parasitic element, it is possible to prevent the antenna gain from decreasing. Furthermore, since the parasitic element and the feeding element are formed in the same layer and the number of elements can be reduced, the antenna can be downsized, and the radiation pattern has an advantage that it does not depend on frequency.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing a microstrip antenna according to an embodiment of the present invention. In FIG. 1, 11 is a ground plane, 12 is a dielectric substrate, 13 is a feeding point, 14 is a feeding element, 15 is the same size as the feeding element 14, and one non-radiating end 14 a of the feeding element 14 has its own non-radiating end 14 a. Parasitic elements with radiation ends 15a arranged in parallel and coupled, 16 and 17 are the feeding element 14 and the parasitic element 15
Of the same size, which are coupled in parallel with the respective radiation ends 14b, 14c and 15b, 15c. These feeding element 14 and parasitic element 15,
16 and 17 are formed on the dielectric substrate 12 in the same layer. 1
Reference numeral 8 is a lumped constant component loaded between the feeding element 14 and the parasitic element 16 on the side of the one radiation end 14b.

Next, the operation of the above embodiment will be described.
When the parasitic element 15 having the same size as that of the feeding element 14 is loaded on one of the non-radiating ends 14a of the feeding element 14, the antenna becomes
As shown in FIG. Further, the radiation ends 14b, c and 15b, c of the feeding element 14 and the parasitic element 15 respectively.
When parasitic elements 16 and 17 of the same size are loaded on
The gain of the antenna is improved. Further, when the lumped constant component 18 is loaded between the feeding element 14 and the parasitic element 16, the input VSWR characteristic is improved within the band of two resonances as shown in FIG.

As described above, according to the above-described embodiment, by loading the lumped constant component 18 between the feeding element 14 and the parasitic element 16, the band can be widened, and the feeding element 14 can be used.
By loading the parasitic elements 16 and 17 on the respective radiation ends of the antenna, it is possible to prevent the antenna gain from decreasing.
Further, since the parasitic elements 15, 16 and 17 are in the same layer as the feeding element 14 and the number of elements is as small as 3, the antenna can be downsized, and the radiation pattern does not depend on the resonance frequency.

In the above embodiment, the lumped constant component 18
Is loaded between the parasitic element 16 and the feeding element 14, but the parasitic element 15 and the parasitic element 16 are connected or the parasitic element 15
It may be loaded between the power feeding element 14 and the power feeding element 14.

[0013]

As described above, according to the present invention, a parasitic element is coupled to one non-radiating end of a feeding element on the same layer, and further, the radiating ends on both sides of the feeding element and the parasitic element are respectively connected. Since the parasitic elements are coupled on the same layer, it is possible to realize a microstrip antenna that is small and has substantially no deterioration in antenna characteristics.

Further, according to the present invention, since the lumped constant parts are loaded between the parasitic elements and the feeder elements or between the parasitic elements, a wide band can be achieved even with a small number of parasitic elements.
Further, since there are few parasitic elements, there is an advantage that the radiation pattern does not depend on the resonance frequency.

[Brief description of drawings]

FIG. 1 is a perspective view of a microstrip antenna according to an embodiment of the present invention.

FIG. 2 is an input VSWR characteristic diagram of the same antenna when a lumped constant component is not loaded.

FIG. 3 is an input VSWR characteristic diagram when a lumped constant component is loaded in the antenna.

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

FIG. 5 is a sectional view showing another example of a conventional wideband microstrip antenna.

[Explanation of symbols]

 11 ground plane 12 dielectric substrate 13 feeding point 14 feeding element 14a, 15a non-radiating end 14b, 14c, 15b, 15c radiating end 15 parasitic element 16, 17 parasitic element 18 lumped constant component

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Sato Inventor Kenichi Sato 2-chome, 2-5-Akiradori, Izumi-ku, Sendai-shi, Miyagi Matsushita Communication Sendai Research Institute (72) Inventor, Kazuhide Yamada Izumi-ku, Sendai-shi, Miyagi 2-5-Chome, Mitsudori Matsushita Communication Sendai Research Institute

Claims (3)

[Claims] 1. A parasitic element is formed by coupling one non-radiating end of a feeding element formed on a dielectric substrate on a ground surface, and the radiation ends on both sides of the feeding element and the parasitic element. A microstrip antenna formed by coupling parasitic elements to each. 2. The microstrip antenna according to claim 1, wherein a lumped constant component is loaded between the feed element and the parasitic element. 3. The microstrip antenna according to claim 1, wherein a lumped constant component is loaded between the parasitic element and the parasitic element.