Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
2001-12-06
2003-05-27
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343S912000, C342S008000
Reexamination Certificate
active
06570545
ABSTRACT:
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable.
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention relates generally to radar reflectors, and more particularly to a lightweight radar reflector comprising a plurality of conterminous corner reflectors, wherein the radar reflector is adjustably supported and positioned within an inflatable structure when the inflatable structure is inflated with air, gas or lighter-than-air gas.
In the past, corner radar reflectors, which typically consist of three planar surfaces suitable for reflecting radio frequency waves and connected together at right angles to each other, have been utilized for a number of military and commercial purposes. When radio frequency waves, emitted towards the radar reflector within a range of angles relative to the reflector center, strike the reflector they reflect directly back toward the source of emission. Consequently, a radar transceiver receiving such reflected radio frequency waves will indicate that the radar cross-section of the detected radar reflector is much bigger than the reflector actually is. Because of this feature, namely the ability to indicate a large radar cross-section relative to actual size, corner-type radar reflectors find particular applicability in military and industrial uses as floating and aerial radar decoys and beacons.
Disposing a collapsible radar reflector within an inflatable structure is particularly efficacious because the combined apparatus may be folded or otherwise compacted for storage using a minimum of storage space. Past radar reflectors have been constructed of lightweight materials to improve ease of handling and storage, and to enable the apparatus to float in the atmosphere when inflated with lighter-than-gas. In operation, such radar reflector apparatus are typically inflated with air, gas or a combination thereof so that as the inflatable structure inflates it imparts force to the radar reflector disposed therein in a manner to position the radar reflector to reflect radar waves when the inflatable structure is fully inflated. The inflatable structure may then, depending upon relative weight of the gas it is inflated with, be employed as an aerial or surface radar decoy or beacon. In the past, such decoys or beacons have typically been deployed as aerial radar beacons floating above terrain, or floating on the surface of the sea as ship radar decoys.
Past apparatus having an inflatable structure with a radar reflector disposed therein have, however, suffered from several disadvantages. For instance, when in use the effect of wind and other environmental forces upon the outer surface of the inflatable structure often imparts torsional and other forces to the radar reflector disposed within such that the shape of the radar reflector is thereby distorted. The ability of the radar reflector to optimally reflect radar waves is substantially degraded. Therefore, past apparatus lack the ability to effectively isolate the radar reflector supported within the inflatable structure from the effect of environmental forces imparted to the outer surface of the inflatable structure.
Another disadvantage of past inflatable structures with a radar reflector disposed therein has been that the radar reflector is affixed to the inflatable structure by a process that requires puncturing the surfaces of the inflatable structure. Such a process of affixation is detrimental to the structural integrity of the inflatable structure, and encourages leakage when the inflatable structure is inflated with air or gas. When the air or gas leaks out, the inflatable structure deflates and the radar reflector's positioning to reflect radar waves is degraded. Therefore, past systems that include processes of affixing the radar reflector to the inflatable structure that require puncturing the surfaces of the inflatable structure are inherently disadvantageous.
Still another disadvantage of past inflatable structures with a radar reflector disposed therein has been that there is no method for a user to easily adjust the position of the radar reflector within the inflatable structure when the structure is inflated. As discussed previously, past radar reflector apparatus have been manufactured so that the apparatus may be folded or otherwise compacted for storage or transportation using a minimum of storage space. The radar reflector of past apparatus is typically permanently attached to the inner surface of the inflatable structure during manufacture. Due to the rigors of prolonged storage, the inflatable structure may not inflate to its intended symmetrical shape when it is inflated. Instead, the inflatable structure may inflate asymmetrically. Consequently, the radar reflector, which depends on such symmetrical inflation to optimally position it within the inflatable structure is not properly positioned within the non-uniform, inflated structure. Past radar reflector apparatus typically lack a convenient method for the user to manually adjust the position of the radar reflector within the inflatable structure after the structure has been inflated.
Yet another disadvantage of past inflatable structures with a radar reflector apparatus disposed therein has been that the shape of the inflatable structure is not conducive to securely positioning the radar reflector within the inflatable structure. Past apparatus typically use a spherical-shaped inflatable structure. While such a structure lends itself to uniform inflation, it does not provide any substantially planar surfaces upon which to affix the radar reflector within the structure. Consequently, the radar reflector is prone to being dislodged out of an optimal position to reflect radar waves when the apparatus is in use.
Information relevant to attempts to address these problems can be found in U.S. Pat. No. 2,463,517 (Chromak), U.S. Pat. No. 2,534,716 (Hudspeth et al.), U.S. Pat. No. 2,888,675 (Pratt et al.), U.S. Pat. No. 3,276,017 (Mullin), U.S. Pat. No. 4,673,934 (Gentry et al.) and U.S. Pat. No. 5,457,472 (Bjordal et al.). However, each one of these references suffers from one or more of the following disadvantages:
U.S. Pat. No. 2,463,517 (Chromak) does not disclose a means for a user to conveniently adjust the position of the radar reflector within the inflatable structure when the structure is inflated. Chromak also does not teach an inflatable structure having a plurality of planar surfaces.
U.S. Pat. No. 2,534,716 (Hudspeth et al.) does not disclose a means for a user to conveniently adjust the position of the radar reflector within the inflatable structure when the structure is inflated. Hudspeth also does not teach a means to effectively isolate the radar reflector supported within the inflatable structure from the effect of environmental forces imparted to the outer surface of the inflatable structure.
U.S. Pat. No. 2,888,675 (Pratt et al.) does not teach an inflatable structure having a plurality of planar surfaces. Further, Pratt does not disclose a means for a user to conveniently adjust the position of the radar reflector within the inflatable structure when the structure is inflated. Pratt also does not teach a means to effectively isolate the radar reflector supported within the inflatable structure from effect of environmental forces imparted to the outer surface of the inflatable structure.
U.S. Pat. No. 3,276,017 (Mullin) does not disclose a means for overcoming asymmetric inflation of the inflatable structure. In addition, Mullin does not teach a means for adjusting of the positioning of the corner reflector support members without disassembling the entire apparatus. Further, because the support members of Mullin are permanently attached to the inner surface of the inflatable structure, there is a risk that the corner reflector could tear the inflatable structure, thus degrading the utility of the apparatus as a radar reflector.
U.S. Pat. No. 4,673,934 (Gentry et al.) does not teach an inflatable structure having a plurality of planar surfaces. Further, Gentry
Snow Jeffrey M.
Tennant Charles W.
Le Hoang-anh
Lopes, Esq. Crane L.
The United States of America as represented by the Secretary of
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