Communications: radio wave antennas – Antennas – Switching between antennas and lines
Reexamination Certificate
1999-08-09
2001-02-27
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Switching between antennas and lines
C343S745000
Reexamination Certificate
active
06195065
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to antennas whose dimensions may be modified so as to modify their radioelectric characteristics with the objective, generally, of making them work, by choice, in one out of several frequency bands; these antennas are mainly used at frequencies below 1 GHz.
2. Discussion of the Background
Antennas are known which comprise at least one radiating element having variable electrical length, which is constructed from an array of n, with n an integer greater than 1, conducting sections separated by switching modules designed to electrically link together all or some of the sections. Onwards of that of its two ends where it is fed, the array constitutes a radiating element which is made, by choice, of 1, 2, . . . n sections. This is the way in which, in particular, variable geometry unipole antennas are constructed.
In certain cases the switching modules consist simply of fixing means, generally a screw and a nut carried respectively by the opposite ends of the sections to be joined electrically. When joining is to be controlled remotely for reasons of ease and/or speed of implementation, it is a known practice to use a switching module of the electrical relay type and linking means made of two electrical wires for controlling the relay; the presence of these wires which are radioelectrically insulated from the conducting sections in a more or less effective manner, limits the performance of the antenna and this limitation is all the greater when the antenna caters for high powers or high voltages, as is the case with antennas operating with decameter waves.
It should also be noted that it is known practice, through U.S. Pat. No. 4,728,805, to construct antennas from a three-dimensional matrix whose rows are made of conducting segments with, at the intersections of the rows, photoconducting elements which provide connections between segments when they are illuminated. On account of the photoconductors available on the market, this technique can only be used with low-power antennas and, moreover, these photoconductors must be permanently illuminated in order to be maintained in the on state.
SUMMARY OF THE INVENTION
The objective of the present invention is to avoid the aforementioned drawbacks in antennas whose geometry can be adjusted remotely.
This is achieved by virtue of a remote control which implements linking means which do not disturb the radioelectric operation of the antenna and which are associated with switching means which may be chosen so as to cater for high powers or high voltages.
According to the present invention this is implemented by antennas such as defined on the one hand in the first aspect and on the other hand in claim
2
.
The antenna according to claim
1
comprises switching sections comprising an electromechanical relay with two stable states which is controlled by two photovoltaic devices which are themselves respectively controlled by two fibre optic cables. In relation to this antenna should be noted the U.S. Pat. No. 5,293,172 which describes an antenna in which antenna sections are linked together with switching modules comprising an electronic relay with two states, which is controlled by a photovoltaic device which is itself controlled by a fibre optic cable; this antenna has, in particular, two drawbacks:—the relay does not make it possible to pass high powers—to maintain one of the two states the photovoltaic device must be permanently illuminated.
The antenna according to the second aspect comprises antenna sections linked together by switching modules comprising a conducting piece which is made to slide along the antenna by an insulating rod, thus making it possible to couple two sections of the antenna; in this antenna which is located above an earth plane, the insulating rod traverses the earth plane and thus it is possible to manoeuvre the rod from beneath the earth plane, thereby avoiding disturbance to the operation of the antenna. In relation to this antenna should be noted patent application EP-A-0 428 229 which describes an antenna made of antenna sections with, for linking together two consecutive sections of the antenna, a bistable electromechanical relay “incorporated” into the gap between the two relevant sections; this relay comprises contacts having two positions, a rod for moving the contacts and two devices for driving the rod which are controlled from signals tapped off from the antenna with the aid of wires; this antenna comprises, for linking two sections, certain elements which are comparable to those of the second aspect but on the one hand it does not comprise the “conducting piece which slides” and which permits large powers and high voltages and on the other hand all its constituent elements are incorporated into the gap between the relevant sections and therefore affect the operation of the antenna in contradistinction to what occurs in the antenna according to the second aspect where the second end of the insulating rod is located under an earth plane so that the means for driving the insulating rod can be arranged under this earth plane.
The present invention will be better understood and other characteristics will become apparent with the aid of the following description and of the figures relating thereto which represent:
REFERENCES:
patent: 3129386 (1964-04-01), Daly
patent: 4564843 (1986-01-01), Cooper
patent: 4751513 (1988-06-01), Daryoush et al.
patent: 4763126 (1988-08-01), Jawetz
patent: 4924238 (1990-05-01), Ploussios
patent: 5093668 (1992-03-01), Sreenivas
patent: 5293172 (1994-03-01), Lamberty et al.
patent: 5367310 (1994-11-01), Warnagiris
patent: 5656931 (1997-08-01), Lau et al.
patent: 10 49 556 (1971-04-01), None
patent: 0 428 229 A1 (1991-05-01), None
Hung Frederic Ngo Bui
Kretschmer Sylvain
Rebernak William
"Thomson-CSF"
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Phan Tho
Wong Don
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