JPS63148704A - Microstrip antenna - Google Patents

Abstract

PURPOSE:To execute matching of the impedance by providing a capacitance portion between a feeding part of a patch-like radiator and a contact part of the center conductor of a coaxial line. CONSTITUTION:When an interval of a patch-like radiation conductor 1 and a ground conductor is >= about 5mm, a capacitor component is constituted in a feeding part of the conductor 1 by a circular pipe metallic fixture 7 and a dielectric 8, in order to negate a lead inductance component in the center conductor 5 of a coaxial line 4 for executing a feed to the conductor 1 through the inside of a honeycomb 2. In such a way, by forming a simple structure, matching of the impedance can be executed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a microstrip antenna, and particularly to a microstrip antenna suitable for impedance matching when the distance between the patch-shaped radiating conductor and the ground conductor of the antenna is large, such as in a honeycomb structure. Regarding microstrip antennas.

[Conventional technology]

Generally, a microstrip antenna has a structure in which a patch-like radiating conductor and a grounding conductor are installed in parallel, and a dielectric material, a honeycomb core, etc. is sandwiched between them.

Then, a coaxial line with a center conductor inside is connected from the ground conductor side to the patch-shaped radiation conductor on the surface through a dielectric material, etc.
The microstrip antenna is driven by using the connection point as a feeding point.

Note that this type of microstrip antenna is
For example, Japanese Utility Model Application Publication No. 61-29515 can be mentioned.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, when the distance between the patch-like radiating conductor and the ground conductor of the microstrip antenna increases to about 5nwn or more, the center conductor of the coaxial line passing through the dielectric also becomes long, and the center conductor becomes parasitic. There was a drawback that impedance matching could not be achieved due to the inductance.

For this reason, in the prior art, it is difficult to drive directly from a coaxial line, and it is necessary to add an external impedance matching circuit.

An object of the present invention is to provide a microstrip antenna that can achieve impedance matching with a simple structure.

[Means for solving problems]

The above object is achieved by providing a capacitance for canceling the parasitic inductance between the feed section of the patch-shaped radiating conductor of the microstrip antenna and the contact section of the center conductor of the coaxial line.

[Effect]

Usually, impedance matching is achieved by establishing a mutually reciprocal relationship. In the case of the microstrip antenna of the present invention, the parasitic lead inductance in the center of the unbalanced drive circuit is a factor that disturbs impedance matching, so it is necessary to add a capacitor component that co-acts with this lead inductance. If this is possible, impedance matching becomes possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of a microstrip antenna according to an embodiment of the present invention, in which 1 is a patch-like radiation conductor, 2 is a honeycomb, 3 is a grounding conductor, 4 is a coaxial line connected to the drive circuit of the microstrip antenna, and 5 is a center conductor of coaxial line 4,
6 is a short-circuit wire connecting the patch-like radiation conductor 1 and the ground conductor 3;
7 is a circular pipe fitting installed at the power feeding part of the patch-shaped radiation conductor;
Further, 8 is a dielectric material embedded in the circular pipe gold x'(-0 to constitute a capacitor component, to which the center conductor 5 of the coaxial line is connected.

If the distance between the patch-like radiating conductor 1 and the ground conductor 3 is approximately 5 mm or more, the influence of the lead inductance component will be It becomes impossible to ignore. An equivalent circuit of such a conventional microstrip antenna is shown in FIG. 2(a). In the figure, 9 is a lead inductance component due to the center conductor 5, and this lead inductance component 9 makes it impossible to match the impedance of the antenna.

In this embodiment, in order to cancel this lead inductance component 9, a capacitor component is formed in the power feeding portion of the re-patch-like radiating conductor 1 using the circular pipe fitting 7 and the dielectric 8. Here, the circular pipe fitting 7 has the function of fixing the center conductor 5 within the dielectric 8, and also has the function of adjusting the capacitance of the capacitor component by changing the overall length or thickness including the dielectric 8. It is something that has.

Therefore, the equivalent circuit of the power feeding part of the microstrip antenna shown in FIG. 1 is as shown in FIG. It can be seen that it acts to eliminate the light (ωL-1 = 0).

In this embodiment, the circular pipe fitting 7 and the dielectric material 8 are used as means for configuring the capacitor component, but the present invention is not limited to this. Any material that can form a capacitor component with variable capacitance may be used.

〔Effect of the invention〕

According to the present invention, an impedance matching circuit that should be added externally is built into the feeding part of the antenna by changing the structure of a part of the microstrip antenna within a range that does not affect the characteristics of the antenna. Therefore, impedance matching can be performed with a simple structure.

Furthermore, in terms of productivity, antennas with uniform characteristics can be manufactured efficiently, and the structure is simple, so the antenna is excellent in reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a microstrip antenna according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit of a conventional system and a power feeding section of the present invention. 1... Patch-like radiating conductor, 2... Honeycomb. 3...Grounding conductor, 4...Coaxial line, 5...
...Center conductor, 6...Short wire, 7...
Circular pipe fitting, 8... Dielectric, 9... Lead inductance component, 10... Capacitor component. 1 country 2 countries

Claims (1)

[Claims] 1. In a microstrip antenna formed by installing a patch-shaped radiation conductor and a ground conductor in parallel, the antenna has a capacitance component in the power feeding part of the patch-shaped radiation conductor in order to cancel the inductance component parasitic to the antenna drive circuit. microstrip antenna.