JPH088445B2 - Microstrip antenna structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a microstrip antenna that is effective in improving the gain of a microstrip antenna used for direct satellite broadcast reception and preventing noise.

(Prior Art) Microstrip antennas are being developed as those related to parabolic antennas for direct transmission and reception of satellite broadcasts and communications in the microwave band.

As shown in FIG. 4, the structure is such that a grounding conductor 10 formed on the entire lower surface of a dielectric 11 and a resonance element 12 and a feed line 13 for radio wave radiation are formed on the upper surface of the dielectric 11. . The resonant element 12 is a square patch type, but various shapes such as a polygonal patch type, a circular patch type, a crank type, and a dipole type have been proposed. Often formed on the same plane as a microstrip line.

(Problems to be solved by the invention) In this type of antenna, since the resonance element 12 and the feed line 13 are on the same plane, unnecessary radiation of radio waves occurs on the feed line other than the resonance element, and its loss is neglected. It ’s too big to do.
As a solution to this, a structure as shown in FIG. 3 can be considered. This moves the resonance element 7 and the feed line 4 to another surface, and the feed line 4 has a triplate structure in which the upper and lower sides of the feed line 4 are sandwiched by the ground layers 5 and 6 to prevent unnecessary radiation from the feed line 4 to the free space. Is what you are trying to do.

According to such a structure, not only unnecessary radiation from the power supply line is small, but also the power supply line can be freely arranged. However, since the conductor 8 connecting the feed line 4 and the resonant element 7 and the feed line 4 are discontinuous at the junction, there is unnecessary radiation from that part, and the purpose of improving the antenna gain or reducing noise cannot be achieved. There was such a problem.

The present invention proposes a structure of a microstrip antenna that solves these problems.

(Means for Solving the Problems) According to the present invention, the object is to provide the first and second ground layers.
This can be achieved by providing a shield earth conductor, which is electrically connected to these earth layers and is close to the power supply line, between the five and six.

The present invention will be described below with reference to the drawings illustrating an embodiment. The microstrip antenna according to the present invention is the first
As shown in FIG. 2 and FIG. 2, first and second dielectric substrates 1 and 2, a feed line 4 sandwiched by these dielectric substrates, a lower surface of the first dielectric substrate, and a second dielectric. First and second ground layers 5 and 6 formed over substantially the entire upper surface of the substrate, a third dielectric substrate 3 provided on the upper surface of the second ground layer 6, and the third dielectric layer 3. It includes a resonance element 7 formed on the surface of the body substrate for radio wave radiation and a conductor 8 connecting the resonance element and the feed line 4, and is sandwiched between the first and second ground layers in the vicinity of the feed line 4. It is characterized in that a shield earth conductor 9 which is electrically connected to these earth layers is provided.

As a material of the dielectric substrate, a material having a low relative permittivity (ε _r ) and a dielectric loss tangent (tan δ) is used in order to suppress the loss of the power feeding line. For example, a fluorine resin or a polyolefin resin is preferable. The first, second and third dielectric substrates may be made of different materials.

Since the first and second earth layers, the feed line, the resonance element, and the like need to be conductors, it is common to use a metal foil or a metal plate. Specifically, a copper foil or an aluminum plate is used. Are used.

The shield earth conductor may also be a plating film using a metal foil or a metal plate. Since the purpose of the shield ground conductor 9 is to suppress unnecessary radiation in the portion connecting the power feeding line 4 and the resonant element 7, it is necessary that it is at least on the extension line of the power feeding line in the connecting portion. As shown in FIG. 5, it is best to surround the entire feed line 4 and the connecting conductor 8 with the shield earth layer 9. The distance between the power feed line and the shield ground conductor varies depending on the thickness of the dielectric substrate, the relative permittivity, the frequency, etc., but is preferably 1/1 to 1/16 of the wavelength.

(Example) A two-point feeding circular patch type 256-element microstrip antenna having the structure shown in FIG. 2 and FIG. 5 was prototyped and its gain was measured. A gain improvement of about 20% was obtained.

(Effects of the Invention) As described above, according to the present invention, it is possible to provide a microstrip antenna in which there is no radiation loss at the discontinuity of the feeding system and coupling loss between the antennas due to unnecessary radiation, and the gain is significantly improved. became.

[Brief description of drawings]

1 and 2 are sectional views of a microstrip antenna according to the present invention, FIGS. 3 and 4 are sectional views and perspective views of a conventional microstrip antenna, and FIG. 5 is a microstrip antenna according to the present invention. FIG. Explanation of reference numerals 1, 2, 3 ... Dielectric substrate, 4 ... Feed line 5, 6 ... Ground layer, 7 ... Resonant element 8 ... Connection conductor, 9 ... Shielding ground conductor 10 ... Ground conductor, 11 ... Dielectric 12 ... Resonant element, 13 ... Feed line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Yokota 1500 Ogawa, Shimodate-shi, Ibaraki Hitachi Chemical Co., Ltd. Shimodate factory (72) Inventor Yutaka Yamaguchi 1500 Ogawa, Shimodate-shi, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Research Center (72) Inventor Satoshi Tasaki 1500 Ogawa, Shimodate City, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Research Center (72) Inventor Masahiko Ota 1500 Ogawa, Shimodate City, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Research Center ( 72) Inventor Takao Sugawara 1500 Ogawa, Shimodate, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor Hiroyuki Iyama 1500, Ogawa, Shimodate, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd.

Claims (1)

[Claims] 1. A first dielectric substrate and a second dielectric substrate, a feeding circuit network sandwiched between the first dielectric substrate and the second dielectric substrate, and a first dielectric substrate. First and second ground layers formed over substantially the entire lower surface of the body substrate and the upper surface of the second dielectric substrate; and a third dielectric substrate provided on the upper surface of the second ground layer. A microstrip antenna including a resonance element for propagating radiation formed on a surface of a third dielectric substrate and a conductor connecting the resonance element and a feeding line of the feeding circuit network, wherein A structure of a microstrip antenna, characterized in that a shield earth conductor is provided between the two earth layers and is electrically connected to the earth layers and is close to the feed line.