JPS60103A - Beam width variable antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a variable beam width antenna, and more particularly to a variable beam width antenna used in a wireless communication line where duct fading occurs.

(b) Conventional technology and problems Multiplex radio equipment using microwaves is widely used, but fading can occur when the propagation distance is long, when propagating over sea, and depending on the atmosphere through which the low radio waves pass. There is.

The main types of fading are duct-induced fading, which occurs when the propagation path of radio waves is bent due to changes in the refractive index distribution of the atmosphere, and duct fading, which occurs when two waves are split due to the phase state of the direct wave and reflected wave received at the same time. There are some that are caused by canceling each other out or adding to each other.

Measures against duct fading include a space-diaperity method, a frequency-diaperity method, and a method of increasing transmission power. However, the space diversity method requires two systems of antennas and receivers, and the frequency diversity method requires two systems of 48 transmitters and receivers. Furthermore, in the case of an increase in transmission power, a high output power amplifier is required.

That is, an antenna and a transmitter/receiver are additionally required, and these devices and conventional devices must be operated in parallel or in a switched manner, resulting in a complicated configuration and an increase in price.

(c) Purpose of the Invention The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide a variable beam width antenna that reduces the effects caused by the occurrence of duct fading.

(d) Structure of the Invention The object of the above invention is to provide an antenna that is composed of a main reflector, a sub-reflector, a primary radiator, etc., and that the reception level received by the antenna is determined continuously for a certain period of time. a means for detecting that the value is below a value, a means for controlling a sub-reflector drive section installed on a disk fixed by a plurality of sub-reflector supports using the output from the detecting means; This is accomplished by providing a variable beam width antenna characterized by comprising means for moving the sub-reflector in parallel by the sub-reflector drive section.

(e) Examples of the invention FIG. 1 is a diagram for explaining one embodiment of the present invention.

In the figure, 1 is the main reflecting mirror surface, 2I'i primary radiator, 3 sub-reflector mounting columns, 31 is a disk, 32 is a reinforcing member, 33 is a column, 4 is a sub-reflector, 41 is a sub-reflector column , 42 is a sub-reflector plane, 43 is a sub-reflector column, 5 motors, 6 is a crank mechanism, 7 is a feeder, RX is a receiver, P/N is a reception level detector, and OUT is an output terminal. .

These parts are connected as follows.

For example, one end of three sub-reflector mounting struts 3 having the same length are attached at three locations on the main reflecting mirror surface having the shape of a paraboloid of revolution (at the same circumference around the axis of rotation of this paraboloid of revolution). The other end is fixed to the end of a common disk 31, respectively, at the points located above and dividing this inner periphery into three equal parts. And this day board 3
Hollow pillars 33 are fixed with rivets or the like at the center of this disk and at points dividing the circumference of this concentric circle into three equal parts according to the plane of the main reflecting mirror 1. This support 33 is fixed to the support 3 of the sub-reflector driving section by a reinforcing member 32 for reinforcement.

In addition, the hyperboloid of revolution part of the sub-reflector 4, which is shaped by cutting out the hyperboloid of revolution with a plane perpendicular to the rotation axis, faces the main reflector surface 1 and is perpendicular to the sub-reflector plane 42, which is a perpendicular plane. Three sub-reflector columns 41 are fixed. The sub-reflecting mirror columns 41 are movably fitted in the hollow portions of the corresponding columns 33, respectively. Further, a sub-reflector support column 43 fixed perpendicularly to the center of the sub-reflector plane 42 is connected to the rotating shaft of the motor 5 via, for example, a crank mechanism 6 that converts rotational motion into linear motion.

Next, the bottom surface of the conical opening, which is fixed in the center hole of the main reflecting mirror surface and has the pointed end removed on a plane parallel to the bottom surface, is aligned with the sub-reflecting mirror 4. The ζ-cut portion is connected to the input terminal of the receiving section RX via a feeder, and the first output terminal of this receiving section RX is connected to the external output terminal O.
UT and the second output terminal are respectively connected to the input terminal of the motor 5 via a reception level detector P/N.

The operations of each part connected in this way are as follows.

First, in the case of normal reception, antenna 2 shown in Figure 1
The positions of the two mirror surfaces are as follows: When the focal point of the main reflecting mirror 1 is 02 and the equivalent focal point determined by the radiation characteristics of the primary radiator is O7, the two focal points OI and 02 of the sub-reflecting mirror 1-1 are the concomitant focal point. It is a hyperboloid of rotation. In this case, the main reflector 1
The radio waves radiated from are radiated to the outside in a parallel state. On the other hand, the radio wave (2) received in the child-rearing state is reflected by the main reflection @1 and the sub-reflection mirror '4, and is focused at point 02. Then, the collected radio waves are applied to the receiver RX through the feeder 7, where they are amplified by 9 frequency conversion, demodulated, and the extracted demodulated waves are taken out from the terminal 1, but the signal frequency band to be transmitted is For example, noise components and pilot signals contained in the upper frequency band are added to the reception level detector P/N. Here, the level of the miscellaneous component and pilot signal is detected and determined.The reception level is determined by comparing it with the level of the noise component and pilot signal corresponding to the reception level (for example, a level below the standard reception level). If the received level is also higher than the received level, the output of the received level detector P/N is 0 and the motor 5 does not operate.

Therefore, it does not receive radio waves outside the radio wave (■), and the antenna captures the radio waves with its narrowest beam width.

Next, when duct fading occurs and the input level of the receiving section falls below the standard receiving level, the noise component extracted from the receiving section RX corresponding to the receiving input level will not have a high level, but the pilot signal The signal-to-noise ratio of is small. When such noise components and pilot signals are added to the reception level detector P/N, this detector determines from the signal-to-noise ratio of the noise components and pilot signals that the current reception level is below the predetermined reception level. I understand that. When the reception level detector P/N detects that the current reception level has been below the predetermined reception level for a period of time 1 or more, the output corresponding to the difference from the predetermined reception level is It is sent to the motor 5 from the detector P/N.

The motor 5 is rotated by this output, and the crank mechanism 6 converts this rotational motion into a linear motion, and the sub-reflector column 43 moves to push the sub-reflector 4 toward the main reflector surface 1. At this time, the three sub-reflecting mirror columns 41 provided on the sub-reflecting mirror plane use the hollow portions of the pillars 33 as guides, so that the sub-reflecting mirror surface 4 moves smoothly and in parallel to the main reflecting mirror surface. It's coming soon.

This expands the beam width of the antenna and makes it possible to capture stain waves. When the reception level reaches a predetermined reception level or higher, the motor 5 stops at that point and the movement of the sub-reflector 4 is stopped.

If the reception level falls below the dead value again while receiving in such an antenna state, the position of the sub-reflector 4 is returned to the state in which it receives radio waves, and from this position the sub-reflector 4 is redirected from this position as described above. Move the reflecting mirror 4 (f) As described in detail, according to the present invention, by moving the sub-reflecting mirror, the beam width of the antenna is expanded and the radio wave propagation path is changed due to p1 duct-related fading. This made it possible to capture radio waves escaping from the antenna.

Therefore, compared to conventional duct-based fading countermeasures that require a separate series of trap receivers, antennas, etc., one series of extra equipment is not required, making the equipment configuration easier and the price significantly reduced. A simple change can have a big effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the present invention. In the figure, 1 is the main reflecting mirror surface, 2 is the primary radiator, 3-digit vernier #,
I mirror mounting column, 4 is the sub-reflector, 5 is the motor, 6 is the crank mechanism section, 71-1: feeder, RX is the receiving section, P/N
is the reception level detector, and OUT is the terminal in No. 1. show. Figure 1 U7

Claims (1)

[Claims] means for detecting, in an antenna comprising a main reflector, a sub-reflector, a primary radiator, etc., that the reception level received by the antenna remains below a predetermined value for a certain period of time; , a means for controlling a sub-reflector drive i installed on a disk fixed to a plurality of sub-reflector supports using the output from the detection means; and means for moving the sub-reflector in parallel.