JPH02274002A - Plane antenna - Google Patents

Abstract

PURPOSE:To widen an interval on the ground surface and to constitute an antenna of a feeding circuit of a low loss by bringing the feeding circuit to multistage constitution in the direction of a radiating circuit. CONSTITUTION:On the ground surface 2, many radiation elements 1 are arranged, and on a feeding circuit 3 for feeding to the radiation elements 1, a main feeding circuit 3a for covering the greater of a plane antenna, and sub- feeding circuits 3b, 3c... of plural stages for coupling use for coupling this main feeding circuit 3a and the radiation element 1 are provided. In such a way, the feeding circuit 3 is brought to multistage constitution in the direction of a radiating circuit. Therefore, an interval between the upper and the lower ground surfaces 2, 4 can be widened, the constitution which can be operated as a line of a lower loss and the feeding circuit 3 of the antenna is obtained, the plane antenna of a lower loss of the feeding circuit (high sensitivity) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flat antenna used for, for example, satellite broadcast reception.

[Prior Art] For example, a power supply circuit is configured with a so-called triplate strip line in which ground planes are provided on both sides of the strip line, a radiating element is provided on one side of the ground plane, and power is supplied to each radiating element by the feed circuit. Figures 4 and 5 show planar antennas. A large number of circular radiating elements 1 are formed on the upper ground plane 2 to constitute a radiating circuit. A power supply circuit 3 is connected between the upper ground plane 2 and the lower ground plane 4.
is provided.

By the way, one of the most important performances of planar antennas is
Sensitivity, which is one of the main features, is increased by reducing the loss of the feeder circuit disposed in the planar antenna, and reducing this loss is very important.

In FIGS. 4, 5, the radiating element 1 and the feeding circuit 3 are placed close to each other (for example, 1 to 2 m+n) and are coupled without contact to operate as an antenna. I couldn't freely (widen) the spacing.

As described above, in the current configuration, there is a rough restriction on the distance between the ground plane 2 and the feeder circuit 3, and the planar antenna is configured only with the feeder circuit 3, which does not sufficiently reduce circuit loss.

Furthermore, from the perspective of power supply circuit loss, microwave waveguides are known to be the line with the least loss. This is the 6th
It is shown in FIG. The waveguide 5 is configured in an H-shape, and the waveguide 5 and the power supply circuit 3 are connected via a coaxial waveguide converter 6. In this case, it is possible to configure a power supply circuit with low loss, but it is often impractical in terms of cost, weight, and fine adjustment of matching to obtain an optimal power supply circuit.

[Problems to be Solved by the Invention] As mentioned above, the loss of the feeder circuit used in the planar antenna is limited by its configuration, making it impossible to configure the antenna with a line with lower loss. ing.

The present invention has been provided in view of the above-mentioned points, and has a configuration in which a line with lower loss can be configured and can also operate as a feeder circuit for an antenna, resulting in a feeder circuit with lower loss (higher sensitivity). The purpose is to provide a planar antenna.

[Means for Solving the Problems] The present invention is characterized in that the feeder circuit has a multi-stage configuration in the direction of the radiation circuit.

[Function] According to the present invention, the feeding circuit is configured in multiple stages in the direction of the radiation circuit, thereby making it possible to widen the interval between the upper and lower ground planes.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Among the feeder circuits used for planar antennas, there are the aforementioned triplate strip line (TSL), microstrip line (MSL) having a ground plane only on one side, and the like. These line losses include radiation loss, dielectric loss, and conductor loss.

For boat fishing, MSL has larger radiation loss than TSL, so the total line loss is not less than TSL.

Therefore, in order to minimize dielectric loss and conductor loss in TSL, the space between the two ground planes should consist of an air layer (foam with a foaming ratio of 10 times or more can be considered equivalent to air). Furthermore, considering conductor loss, it is necessary to construct the device with a wide ground plane spacing.

For example, using an example of the calculation result of TSL loss, the current product has a strip line width of about 21 mm, a distance between the upper and lower ground planes of about 4 mm (the center conductor is located at the center between the ground planes),
If it is formed of an air layer, the loss will be approximately 1.8 dB/m. However, the same strip line width is about 21
However, if the distance between the ground planes is set to about 81, it will be about 1.0d.
B/m, and if the interval is set to approximately 12+nvl, approximately 0
, 7 d 87 m, and the waveguide loss (0.3 dB
/m).

Therefore, in the present invention, for example, the distance between the ground planes is 1
2! A strip line with low loss consisting of +1111 is used for the planar antenna.

Here, if the distance between the ground planes is simply increased to 1211, the distance between the radiating element and the feeding circuit will be about 61111111, which weakens the coupling and degrades the performance (sensitivity) as an antenna. Therefore, in order to make this coupling capability similar to that of the prior art, a multi-stage feeder circuit is provided only near the radiating element. The structure of this invention is shown in FIGS. 1 to 3.

A large number of radiating elements 1 are arranged on the ground plane 2, and a feeding circuit 3 for feeding these radiating elements 1 includes a main feeding circuit 3a that covers most of the planar antenna, and a main feeding circuit 3Et. A plurality of stages of coupling sub-feeding circuits 3b, 3c, . Main power supply circuit 3 above
A is provided approximately at the center of the upper and lower ground planes 2.4.

The number of stages of the sub power supply circuit 3b... is 2.
In this embodiment, two stages of sub-power feeding circuits 3b and 3c are provided. On the ground plane 2 on the opposite side of the radiating element 1, a feeding point with the main feeding circuit 3a is provided. The ground plane 2 uses a metal plate, metal foil, etc., and is used for the main power supply circuit 3a, sub power supply circuits 3b, 3
The ground plane 2 forming the radiating element 1 and the ground plane 2 is made of a thin film covered with metal foil, which is processed into a desired shape by etching or the like. Further, in order to maintain the distance between the ground plane 2.4 and each power supply circuit 3a, a foam or the like that can be regarded as an air layer is used as a spacer.

Here, if the distance between the radiating element and the feeder circuit is about 21 as in the conventional case, sufficient coupling is possible, but in the present invention, the distance between the main feeder circuit 3a and the ground plane 2 is 6+III+1. As described above, two stages of sub power supply circuits 3b and 3c are provided.

By arranging the feeder circuit 3 in this way, the intervals between the radiating element 1 and the sub-feeder circuit 3c, between the sub-feeder circuit 3c and the sub-feeder circuit 3b, and between the sub-feeder circuit 3b and the main feeder circuit 3a are each 21, and the coupling is reduced. I can do it enough. However, this coupling is unlikely to occur in two orthogonal feeder circuits, so if non-contact coupling occurs in each of them, as shown in Figure 3, they should be parallel and overlap (when viewed from above). ) has a length of approximately 1/4 wavelength. That is, as shown in FIG. 1(b) and FIG. 2, the end of the main power supply circuit 3a is formed in a T-shape, the sub-power supply circuit 3b is formed in an L-shape, and the sub-power supply circuit 3c is formed in a 1-shape. There is. Note that the arrows in FIG. 1 indicate radio waves from satellite broadcasting.

In this way, by widening the interval between the ground planes 2.4 of the triplate structure and providing the feeding circuit 3 configured in multiple stages for coupling only in the vicinity of the radiating element 1,
A planar antenna with high sensitivity can be obtained by suppressing the feed circuit loss when looking at the entire antenna. Suppressing this feeding circuit loss not only increases the antenna sensitivity, that is, the antenna gain, but also lowers the noise generated inside the antenna, that is, the antenna noise temperature, which is the index that determines the antenna performance, the so-called antenna performance index. G/
This will greatly improve T.

[Effects of the Invention] As described above, the present invention is characterized in that the feeding circuit is configured in multiple stages in the direction of the radiation circuit. This makes it possible to widen the distance between the ground planes, and therefore, even when the distance between the upper and lower ground planes becomes wider, the feeding circuit and the radiating element can be sufficiently coupled and operate as an antenna. Since the degree of freedom in the spacing between the ground planes is increased and the spacing between the ground planes is widened, it is possible to construct an antenna for a feeding circuit with low loss, and it is possible to obtain a highly sensitive planar antenna.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1(a) and 1(b) are diagrams showing the configuration of a power supply circuit according to an embodiment of the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is a perspective view of the same. FIG. 4 is a plan view of the conventional example, FIG. 5 is a sectional view of the same, FIG. 6 is a rear view of another conventional example, and FIG. 7 is a sectional view of the same. 1 is a radiating element, 2 is a ground plane, and 3 is a feeding circuit 54 which is a ground plane. → Fig. 2 1...Radiating element agent Patent attorney Ishi 1) Chief 7 Fig. 3 Fig. 4

Claims (1)

[Claims] (1) In a planar antenna consisting of a triplate structure consisting of a radiation circuit, a feeding circuit, and a ground plane, in which the feeding circuit and the radiation circuit are coupled without contact, the feeding circuit is configured in multiple stages in the direction of the radiation circuit. A flat antenna characterized by the following.