Communications: radio wave antennas – Antennas – With housing or protective covering
Reexamination Certificate
2000-09-14
2001-11-06
Le, Hoangahn (Department: 2821)
Communications: radio wave antennas
Antennas
With housing or protective covering
C343S705000, C343S708000
Reexamination Certificate
active
06313810
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an atmospheric discharge protection arrangement in an antenna, specially an airborne radar antenna, e.g. arranged on an aircraft.
BACKGROUND OF THE INVENTION
The main requirement for a lightning protection of an airborne radar or other antennas is to provide full protection so that the flight safety of the aircraft is not jeopardized by mechanical damage or loosened parts, which can damage the engine and/or steering parts of the aircraft. At the same time, the protection of the expensive electronics inside or connected to the antenna must be guaranteed.
Moreover, for proper function of the radar, it must be provided with “windows” which are transparent for the radiation (microwave radiation), meaning that the entire housing of the radar cannot be made of conductive material or plastic material reinforced with conductive metal, for preventing damages caused by the strike of the lightning.
DESCRIPTION OF THE RELATED ART
Several types of lightning protections for aircrafts rafts and airborne antennas are known.
WO 98/58398, for example, describes a lightning protection element that may be incorporated into the antenna receiver and signal distribution system of an aircraft. The lightning protection element rejects harmful energy associated with lightning strikes while passing electronic signals without significant interference with those signals. The lightning protecti on element comprises an optical fibre element. The optical fibre rejects damaging energy associated with lighting strikes while passing communications signals transmitted on said signal distribution system.
Through U.S. Pat. No. 5,542,624 a lightning strike protection for an aircraft or part of an aircraft is known, which is provided by mounting metal (aluminium) rods adjacent but spaced from the inner surface of the aircraft wall. The rods are provided with ball joints from which extensions through the wall stand proud of the aircraft outer surface and within the material of static dischargers. The rods are coupled to bus bar which run the length of the aircraft and in turn are coupled to lightning strike dischargers, again in the form of metal rods carried on but spaced from the wall of an aircraft and having extensions which pass through the aircraft wall. The application of the lightning strike protection system to radomes, antennas, pitot tubes carbon fibre reinforced plastics structures is discussed, in the former two cases metal rods being provided to extend in the null field of a device within the radome or the antenna. The mounting of the conductive rods spaced from the wall of the aircraft means that they may safely take surges of electromotive force caused by lightning strikes without damaging the fabric of the aircraft wall.
U.S. Pat. No. 5,353,038 discloses a surface conforming sense antenna integrated with the surface skin of an aircraft by removing a rectangular looped strip of a metallized exterior composite surface skin. The remaining interior metallized portion isolated from the exterior metallized section forms an antenna sense element. The inner metallized portion is connected to an ADF radio receiver to function as a sense antenna in conjunction with a loop antenna. The gap between the metallized inner portion of the exterior metallized section allows lightning energy to be discharged thereacross. The modification does not impose a weight penalty or a wind drag penalty and does not degrade lightning protection for the composite aircraft.
SUMMARY OF THE INVENTION
One of the objects of the present invention is to provide a simple and yet an efficient lightning protection arrangement which protects an antenna, specially an airborne radar antenna both internally and externally.
Another object of the invention is to provide a protection arrangement, which besides mechanical protection of the antenna also provides an efficient protection of the electronics and electrical parts connected to the antenna.
For these reasons the initially mentioned antenna comprises a housing, consisting of at least a first side, a second side, a third side and a fourth side, at least one of said third and fourth sides being at least transparent for electromagnetic waves. The protection arrangement is an internal protection arrangement comprising said first side electrically coupled to said second side through at least one antenna element. The first and second sides consist of a conductive material. The second side is further connected to the hull of said aircraft.
The arrangement further comprises an external protection in form of conductive wires arranged at least on said third or fourth side. In one embodiment, said second side is a part of said hull.
To prevent flashovers said antenna element is at least one antenna plate. Moreover, the first and second sides are electrically coupled together with a low-resistance through said antenna element along the entire length of the antenna.
Preferably, said first and second sides are covered or made by a conductive material.
Moreover, as part of the external protection the conductive wire is arranged to conduct the atmospheric discharge towards at least one of said first and second sides.
Moreover, the antenna can comprise a fifth and a sixth conductive side.
According to a method of the invention, to internally protect an antenna arrangement against atmospheric discharges, the antenna being provided in communication with a hull of an aircraft, said antenna comprising a housing, consisting of at least a first side, a second side, a third side and a fourth side. At least one of said third and fourth sides are at least transparent for electromagnetic waves, said first and second sides consisting of a conductive material. The method comprises the steps of electrically coupling said first side to said second side through at least one antenna element, and connecting said second side to the hull of said aircraft. The method comprises the further step of arranging said third and fourth sides with conductive wires, which wires conduct a discharge current towards said first or second side.
REFERENCES:
patent: 5159521 (1992-10-01), Guangrun et al.
patent: 5353038 (1994-10-01), Osborne et al.
patent: 5405107 (1995-04-01), Bruno
patent: 5542624 (1996-08-01), Smith
patent: 5575438 (1996-11-01), McGonigle et al.
patent: 5862032 (1999-01-01), Cann
patent: 6094171 (2000-07-01), Riddle et al.
patent: 98/58398 (1998-12-01), None
Andersson Carl-Gunnar
Bengtsson Ingemar
Josefsson Bo
Burns Doane , Swecker, Mathis LLP
Le Hoangahn
Telefonaktiebolaget L M Ericsson (publ)
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