JPS605615Y2 - parabolic antenna device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a parabolic antenna device, and provides a device that can be easily and correctly installed in a desired direction.

Parabolic antennas are used to transmit and receive microwaves.

In particular, in recent years, geostationary broadcasting satellites have been developed, and a system for directly receiving television broadcast waves from the satellite in each home is about to be put into practical use, and a parabolic antenna is essential to this system.

Conventionally, in order to correctly point a parabolic antenna in the direction of the satellite, the parabolic antenna was carefully scanned horizontally and vertically, the received electric field strength was measured with a satellite broadcasting receiver, and the installation angle was determined by finding the maximum point. There are ways to adjust.

However, the half-width of the antenna beam of a parabolic antenna is extremely narrow, from 2 degrees for general household use to 1 degree for high-sensitivity antennas used for joint reception, and has very high gain, making it difficult to orient the antenna correctly to the satellite. The task of directing oneself is extremely difficult.

Particularly in the initial stage of antenna installation, the direction of the antenna is not facing the satellite and the received input power is extremely small, so it is difficult to determine the direction of the antenna using the field strength measuring means.

The present invention improves these drawbacks, and one embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is a reflector of a parabolic antenna,
It has an opening surface 11.

A waveguide 3 is movably provided passing through the center of the reflecting mirror 1, and a primary radiator 2 is provided at the tip of the waveguide 3, and a frequency converter 10 is provided at the rear end via a flange 5. It is being

4 is a reinforcing plate attached to the back surface of the reflecting mirror 1, and a waveguide fixture 7 is fixed to the back surface of the reinforcing plate 4; It also penetrates.

A screw 6 for fixing the movement of the waveguide 3 is screwed into the waveguide fixture 7.

Reference numeral 8 indicates a position regulating protrusion provided on the surface of the waveguide 3 between the flange 5 of the waveguide 3 and the waveguide fixture 7; This is a position regulating protrusion provided on the surface.

Push the waveguide 3 forward and attach the waist projection 8 to the waveguide fixture 7
When the primary radiator 2 is brought into contact with the reflector 1, the primary radiator 2 is located exactly at the focal point of the reflector 1, resulting in the maximum gain state, while the waveguide 3 is pushed backward and the protrusion 9 is brought into contact with the reflector 1. In this state, the gain is reduced.

FIG. 2 shows the gain characteristics of the parabolic antenna shown in FIG. 1.

Curve 12 is the state where the gain is maximum, and curve 13 is the state where the gain is reduced.

The maximum gain Gm~ is obtained from the following equation.

Note that S is the aperture area of the parabolic antenna, λ is the wavelength, and η is the efficiency, and a well-designed parabolic antenna has η = 0.
．． It is about 7.

Also, the half width is θ.

−=70 persons/ν (degrees), and D indicates the aperture diameter of the parabolic antenna.

To properly orient the parabolic antenna of the present invention toward the satellite, first push the waveguide 3 backward to create a low gain state, create a thick beam, and scan the parabolic antenna horizontally and vertically. This makes it easy to find peaks when measuring electric field strength.

After roughly finding the peak position in this way, by pushing the waveguide 3 forward, positioning the -order radiator 2 at the focal point, and scanning again only near the peak found above, the direction of the satellite can be determined. You can find it correctly and easily.

The minimum input power that can be measured by measuring the output appearing at the field strength measurement terminal of the satellite broadcasting receiver is equal to the noise level of the receiver, and once the transmission power level is determined, the minimum receiving antenna gain Gmi+ is determined.

That is, the region θ1 connecting the intersection of the curve 12 and the minimum receiving antenna gain Gm1n shown in FIG. 2 is the range in which the direction of the antenna can be adjusted by measuring the voltage from the field strength measuring terminal.

Practical parabolic antennas for receiving television broadcasts from satellites use the minimum necessary size, and the difference between Gmax and Gm1n is about 10 to 15 dB.
θ□ is 4° to 6°.

The reason why the gain is low and is in the state of curve 13 is that the radiated electromagnetic waves are disturbed and the phase and electric field distribution at the aperture surface 11 are no longer uniform.

At this time, the width of the intersection where curve 13 and Gm1n intersect is θ2
, which is wider than θ.

As described above, according to the present invention, when correctly orienting the parabolic antenna in a desired direction, it is possible to first make a coarse adjustment to determine the center of the antenna, and then make fine adjustments to accurately determine the direction. Compared to the past, work efficiency is greatly improved.

In addition, even if the antenna setting direction changes significantly due to a typhoon or earthquake, it can be easily readjusted.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a parabolic antenna device according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram of the device. 1... Parabolic reflector, 2... -order radiator, 3... Equal wave tube, 8, 9... Protrusion.

Claims (1)

[Scope of utility model registration request] A parabolic reflecting mirror, a waveguide provided at the center of the parabolic reflecting mirror so as to be movable in the direction of the central axis of the parabolic reflecting mirror, a radiator provided at the tip of the waveguide 5, A parabolic antenna device comprising a fixing means that can be fixed at a gain position and a low gain position.