Communications: radio wave antennas – Antennas – Antenna components
Patent
1982-10-12
1985-03-19
Lieberman, Eli
Communications: radio wave antennas
Antennas
Antenna components
H01Q 1514
Patent
active
045062706
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a reflecting mirror antenna unit, and is intended to provide a reflecting mirror antenna unit in which a radiation pattern due to the current distribution on the reflecting mirror can be varied readily.
With a conventional antenna unit of the type in which a radio wave radiated by a primary radiator thereof is reflected by a reflecting mirror, it is disadvantageous in that, even if the antenna unit is so designed that for instance a side lobe is low, the side lobe is higher than a desired one for instance because of errors involved in manufacturing the mirror surface. Among these side lobes, one formed in a direction near the bore-sighting axis is often due to the variation of the current distribution which is caused by deformation of the mirror surface. It is difficult to decrease this side lobe.
Heretofore, in order to decrease such a side lobe level, an antenna unit as shown in FIG. 1 is employed. In FIG. 1, reference characters 1a and 1b designate primary radiators, 2a and 2b directional couplers, 3 a resistance attenuator, 4 a phase unit and 5 a main reflecting mirror. The antenna unit is intended to eliminate the side lobe which is formed by an antenna system consisting of the main primary radiator 1a and the main reflecting mirror according to a method in which the primary radiator 1b is added and a part of the signals from the main feeding system, being branched to the directional couplers 2a and 2b, is fed to the primary radiator 1b with suitable phase and amplitude. That is, a particular side lobe can be eliminated by providing a beam which is equal in amplitude to and opposite in phase to the side lobe.
However, the method is disadvantageous in that, when it is required to eliminate a number of side lobes, the arrangement is necessarily intricate as much and accordingly is expensive.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to eliminate the above described drawbacks accompanying the prior art antenna unit, and the object is accomplished by the provision of an antenna unit in which the surface of a reflecting mirror is divided into a plurality of parts, and the parts are made different in thickness from one another, for instance, by bonding metal tapes suitable in thickness thereto, so as to change the phase distribution on the reflecting surface, whereby the configuration of the radiation pattern due to the current distribution on the reflecting mirror is readily changed.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings,
FIG. 1 is an explanatory diagram illustrating the arrangement of a conventional reflecting mirror antenna unit and
FIGS. 2a and 2b illustrate one preferred embodiment of the present invention. More specifically, FIG. 2a is a diagram showing the surface of a reflecting mirror, which has been divided into plural parts, and FIG. 2b is a diagram showing the parts of the reflecting mirror surface, which are made different in thickness from each other.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention, in which the level of a side lobe in a particular direction is decreased, will be described with reference to the accompanying drawings.
In the following preferred embodiment, a main reflecting mirror is used to decrease a radiation field E ( .circle.H , .PHI.) in a direction .circle.H , .PHI.. In FIG. 2b, reference numeral 5 designates a main reflecting mirror and reference numerals 6a, 6b and 6c designate metal tapes different in thickness from one another, which are bonded to the surface of the main reflecting mirror 5. When the main reflecting mirror 5 is divided into N parts as shown in FIG. 2a and the radiation field in a direction .circle.H , .PHI. each of these parts is represented by E.sub.n ( .circle.H , .PHI.), then the following expression (1) is obtained. ##EQU1##
Furthermore, e.sub.n can be represented by a phase .phi..sub.n and an amplitude .vertline.e.sub.n .vertline., that is,
In this connection E.sub.0 is defined
REFERENCES:
patent: 3521288 (1970-07-01), Schell
patent: 4090204 (1978-05-01), Farhat
Katagi Takashi
Kobayashi Yuji
Makino Shigeru
Tanaka Hirokazu
Lieberman Eli
Mitsubishi Denki & Kabushiki Kaisha
Wimer Michael C.
LandOfFree
Reflecting mirror antenna unit with diverse curvature does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reflecting mirror antenna unit with diverse curvature, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reflecting mirror antenna unit with diverse curvature will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-755758