Communications: radio wave antennas – Antennas – Antenna components
Patent
1992-01-21
1994-02-08
Hajec, Donald
Communications: radio wave antennas
Antennas
Antenna components
343916, 343872, 342 8, 342 10, H01Q 1520, H01Q 1518
Patent
active
052852130
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Reflectors providing a substantially uniform response in all directions have been made from three mutually orthogonal plates of metal. The plates may intersect along a centre line. In order to withstand exposure to weather, the metal has to be of substantial thickness and so the reflector is heavy which is inconvenient, particularly for example when the reflector is desired to be hoisted to the masthead of a sailing dinghy.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a reflector comprising reflecting surfaces arranged in mutually inclined planes, the surfaces being formed on blocks of lightweight support material. The surfaces are preferably mutually orthogonal. The support material blocks are secured together with a metallic or dielectric coating on at least one of the facing surfaces, so that the reflecting coatings are not exposed to the weather. Complete protection can be achieved by encapsulating the block assembly and the capsule can provide means for suspending the reflector from a support. The thickness of the coating has only to be sufficient to act as a reflector and not to be self supporting.
In the prior art, reflectors where the metalized surfaces were self supporting and in the form of metal plates, the plates were diamond shaped. Whether the metalized surfaces are self supporting or not, we have discovered that by making the shape of individual metalized surfaces circular or at least closely approximating circular (e.g. polygonal with the number of sides exceeding 4) shape, an improved response is achieved.
According to another aspect of the invention there is provided a reflector comprising a plurality of mutually inclined surfaces, each of which extends on either side of lines in which it intersects another such surface, and has a circular or polygonal (with more than four sides) shape.
Although this reflector is light in weight, the blocks of support material are bulky. We have discovered that it is possible to support the metalized surfaces on elements within an inflatable envelope. The envelope is stored deflated and then expanded for use by air or another gas into a spherical shape then internal metalized elements within the envelope then provide the reflecting surfaces. Thus according to another aspect of the invention, there is provided a reflector comprising a plurality of mutually inclined surfaces, each of which extends on either side of lines in which it intersects another such surface, and the surfaces are elements mounted within an expandable envelope. The elements may be made of wire mesh or textiles and may include stretch fabrics in order to provide reduced resistance to the expansion of the envelope. In each case, the elements will be coated with metal, preferably silver.
The envelope can be inflated with air to a density of less than unity so it will float. Such reflectors can be thrown overboard from a vessel in order to provide a dummy reflector on the surface of the sea. Alternatively, a lighter gas can be used to inflate the envelope so that the reflectors will float in the air, either freely or tethered to a vessel to provide a desired pattern. The tethered reflectors can be return to the vessel when they have served their purpose. The envelopes can be deflated and stored flat for re-use.
Although the elements may be mounted directly to the envelope, it is preferable that they are secured indirectly to the envelope by being secured directly to an intermediate body which is mounted within the envelope.
In one example, the intermediate body is initially formed as a tube with open ends. This allows the elements to be inserted into the tube from one end and secured to its interior wall by any suitable means, such as clamping or stapling as well as by glueing. The ends of the tube are then closed and the tube is mounted within the main envelope. The tube and the envelope are inflated so that the tube changes from a sausage-shape (a cylinder with closed ends) to approximately a spherical shape a
REFERENCES:
patent: 2463517 (1949-03-01), Chromak
patent: 2888675 (1959-05-01), Pratt et al.
patent: 3010104 (1961-11-01), Powell
patent: 3671965 (1972-06-01), Rabenhorst et al.
patent: 4531128 (1985-07-01), Mensa et al.
patent: 4673934 (1987-06-01), Gentry et al.
patent: 4901081 (1990-02-01), Bain, Jr. et al.
Colebrand Limited
Hajec Donald
Le Hoang-anh
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