JPH04213203A - Plane antenna for broad band reception attenuator - Google Patents

Abstract

PURPOSE:To expand a frequency band in which a reception gain of a certain value or above is obtained in the plane antenna receiving a circularly polarized wave signal. CONSTITUTION:A slot pair 8 in which slits 8a, 8b in two directions are used as one set is arranged in spiral based on a prescribed design frequency. A characteristic curve of the reception gain is the sum of the reception gain characteristic curve for each design frequency by setting plural design frequencies thereby expanding the frequency band in which the reception gain of a certain value or above is obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a slot pair consisting of two directional slits on the surface of a planar antenna in which disk-shaped conductors are arranged facing each other, and circularly polarized signals from a satellite are converted into direct current. This invention relates to a planar antenna technology that converts polarized signals for reception.

0002

2. Description of the Related Art Recently, television broadcasting using satellites has become popular. This kind of satellite broadcasting is 10.9
This is done using circularly polarized waves in a high frequency band of 5 to 12.75 GHz. However, it is not possible to process circularly polarized signals as they are, and after converting circularly polarized signals into linearly polarized signals, the signals are processed by a television tuner and video and audio are output.

One of the conventional antennas for receiving such circularly polarized signals is a planar antenna 1 shown in FIGS. 3 and 4. This planar antenna 1 has two upper and lower disc-shaped conductors 2 and 3 disposed facing each other at a predetermined interval, a cavity 5 for installing a probe 4 in the center, and a cavity 5 for installing a probe 4 in the center. A dielectric material 6 such as foamed plastic is filled between and 3. Then, the probe 4 is connected to a low noise block converter (hereinafter referred to as L) via a coaxial cable 7.
NB), and further connected to a signal processing circuit such as a television tuner (not shown). Further, in the upper disk-shaped conductor 2, a pair of slots 8 including two types of slits 8a and 8b in directions perpendicular to the T-shape are arranged spirally from the center of the antenna. The arrangement of the slot pairs 8 is based on the following formula, so that, for example, when receiving a circularly polarized wave signal of the design frequency f1, the radio waves propagated to the probe 4 through each slot pair 8 are received in the same phase. This is done based on.

0004

[Math 1]

In the conventional planar antenna 1 constructed as described above, a circularly polarized wave signal transmitted from a satellite enters the dielectric 6 through the slits 8a, 8b of each slot pair 8. At that time, each pair of slits 8a and 8b
, it is extracted as a vector sum of each vertical component and horizontal component, and becomes a linearly polarized signal. In addition, the signals from the satellite converted into linearly polarized signals in each slot pair 8 are
Since each slot pair 8 is arranged in a spiral shape based on a predetermined calculation formula as described above, all linearly polarized signals obtained from each slot pair 8 have the same phase. In other words, linearly polarized signals of the same phase are propagated into the dielectric 6. This in-phase linearly polarized signal is focused on the probe 4 and transmitted to the LNB electric circuit board, television tuner, etc. through the coaxial cable 7. Then, predetermined video signal processing and audio signal processing are performed.

[0006] Therefore, such a conventional planar antenna 1
The receiving gain is as shown in FIG. That is, in the conventional planar antenna 1, the design frequency for determining the arrangement position of the slot pair 8 is, for example, f1 or f.
It is single like 2nd grade. Therefore, each design frequency f1
Alternatively, the reception gain of the planar antenna 1 obtained when the slot pairs 8 are arranged based on f2 becomes either one of the characteristic curves indicated by the symbol A or B in the figure. In these characteristic curves A or B, the frequency bands in which a receiving gain to the extent that television broadcasting can be enjoyed without any trouble are obtained are the frequency bands shown in a to b in the case of characteristic curve A, and the frequency bands shown in characteristic curve B. In this case, the frequency bands shown are c to d.

[0007]

[Problems to be Solved by the Invention] As described above, the conventional planar antenna 1 has only a single design frequency.
There is a drawback that the frequency band in which a receiving gain to the extent that television broadcasting can be enjoyed without any trouble is obtained is extremely narrow, such as a to b or c to d. That is, in reality, there was a drawback that the number of receivable channels was correspondingly reduced.

[0008]

[Means for Solving the Problems] The present invention improves and eliminates the above-mentioned conventional problems, and provides a reception gain of a predetermined level or higher by mixing slot pairs with different design frequencies. The present invention aims to provide a planar antenna that can expand the frequency band used. Therefore, the means adopted by the present invention to solve the above problems is to provide a slot having a set of slits in two directions on the surface of a planar antenna made of two disc-shaped conductors arranged oppositely, one above the other. In a planar antenna, the pairs are arranged in a spiral according to a calculation formula based on a predetermined design frequency, and the circularly polarized signal from the satellite is extracted as a DC polarized signal using a probe placed in the cavity at the center of the antenna. , a planar antenna for wideband reception characterized in that a plurality of the design frequencies are provided and slot pairs having different design frequencies are mixed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained below based on the embodiments shown in the drawings with reference to the drawings. Note that the same reference numerals as in the conventional case represent the same members. In Figure 1 (
A) is a plan view showing a planar antenna 9 according to a first embodiment of the present invention. As shown by the circle mark in the same figure, this planar antenna 9 has a slot pair 8 consisting of slits 8a and 8b in two directions in an area up to a predetermined distance from the center of the antenna surface at a design frequency. This is calculated using Formula 2 based on f1.

0010

[Math 2]

Further, as shown by the x mark in FIG. 1A, the arrangement of the slot pairs 8 in a region further outward from the region is performed using the predetermined calculation formula based on the design frequency f2. There is. That is, in the planar antenna 9 of this first embodiment, the antenna surface is divided into regions in the radial direction,
A design frequency for arranging slot pairs 8 is set for each section so that slot pairs 8 based on different design frequencies coexist. Other basic configurations are the same as the conventional planar antenna 1 shown in FIGS. 3 and 4. In this way, by mixing slot pairs 8 based on different design frequencies in the same planar antenna 9, the receiving gain characteristic curve obtained with this planar antenna 9 is as shown by the broken line C in FIG. The result is a mixture of the reception gain for the frequency f1 and the reception gain for the design frequency f2. Therefore, in this reception gain characteristic curve C, the frequency band in which a practically usable reception gain to which one can enjoy television broadcasting is obtained is in the range e to f. This range is a to b or c to d when a single conventional design frequency is provided.
It is clear that the range is significantly expanded compared to the range of , and the so-called receivable frequency band is expanded.

FIG. 1B shows a second embodiment of the present invention. In this embodiment, slot pairs 8 based on the design frequency f1 and slot pairs 8 based on the design frequency f2 are arranged alternately, as shown by the O marks and the X marks in the figure. The reception gain characteristic curve obtained in this second embodiment is also C shown by the broken line in FIG. 2, and the same effect as in the first embodiment can be obtained.

By the way, the present invention is not limited to the above-described embodiments, but can be modified as appropriate. For example, although a case has been described in which two types of design frequencies are set, more than two types of design frequencies may be set.

[0014]

[Effects of the Invention] As explained above, in the present invention,
Slot pairs arranged based on different design frequencies are mixed on the same antenna surface, expanding the frequency band of the reception gain characteristic curve compared to when slot pairs are arranged based on a single design frequency. Is possible. In other words, it is possible to increase the number of channels that can be received.

[Brief explanation of the drawing]

FIGS. 1A and 1B are schematic diagrams showing examples of arrangement of slot pairs of planar antennas according to first and second embodiments of the present invention, respectively.

FIG. 2 is a characteristic curve diagram of reception gain of the planar antenna of the present invention.

FIG. 3 is a plan view of a conventional planar antenna.

FIG. 4 is a partial vertical cross-sectional view of a conventional planar antenna.

FIG. 5 is a characteristic curve diagram of reception gain of a conventional planar antenna.

[Explanation of symbols]

8...Slot pair 8a, 8b...slit 9...Planar antenna

Claims (3)

[Claims] Claim 1: On the surface of a planar antenna consisting of two disk-shaped conductors placed opposite each other, a pair of slots each having a pair of slits in two directions are formed in a spiral shape using a calculation formula based on a predetermined design frequency. In a planar antenna in which a circularly polarized wave signal from a satellite is extracted as a DC polarized wave signal using a probe placed in a cavity at the center of the antenna, a plurality of the design frequencies are provided, and slot pairs with different design frequencies are provided. A flat antenna for wideband reception characterized by a mixed antenna. 2. The planar antenna for wideband reception according to claim 1, wherein the slot pairs are divided into sections according to a plurality of design frequencies. 3. The planar antenna for wideband reception according to claim 1, wherein the slot pairs are arranged alternately for each of a plurality of design frequencies.