Communications: radio wave antennas – Antennas – With housing or protective covering
Reexamination Certificate
2001-09-14
2003-10-28
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With housing or protective covering
Reexamination Certificate
active
06639567
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to radomes.
BACKGROUND OF THE INVENTION
Radomes are the housings which shelter an antenna assembly on the ground, on a ship, or on an airplane and the like against the elements. Radomes can be made of many different materials and are generally spherical in shape, shaped like a light bulb, or cylindrical in shape.
Radomes of these shapes, however, fail to meet the radar cross section (RCS) requirements imposed by government agencies. That is, although prior art radomes may adequately shelter the antenna assembly, because of their geometric shape, they have a high RCS and thus can be detected by enemy radar easily. Unfortunately, radar absorbing materials can not generally be used in conjunction with radomes because these materials would cause the blockage of the antenna assembly inside the radome.
The U.S. Government itself proposed a radome with an outwardly diverging wall. But, although this radome geometry seemed to have a lower RCS, its footprint was unacceptably large due to the outwardly diverging wall and thus could not be used in many applications (e.g., on board a ship) where space is a premium. In addition, this radome geometry does not lend itself to retrofit of existing antenna assembly installations.
Accordingly, there is a need for a radome with a low RCS designed such that it does not degrade the radar transmitting performance of the antenna assembly housed by the radome and which also has a footprint similar to existing radomes.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a low radar cross section (RCS) radome.
It is a further object of this invention to provide radome which is proven through testing to meet the United States Government's RCS requirements.
It is a further object of this invention to provide a low RCS radome which does not cause blockage of the antenna assembly inside the radome.
It is a further object of this invention to provide a low RCS radome which does not degrade the transmitting performance of the antenna assembly.
It is a further object of this invention to provide a low RCS radome which has an acceptable footprint.
It is a further object of this invention to provide a low RCS radome which can be retrofitted for use in conjunction with existing antenna assembly installations.
The invention results from the realization that a low radar cross section radome proven in testing to meet the United States Government's requirements and which does not block signals from reaching the antenna assembly inside the radome, which has an acceptable footprint, and which can be retrofitted for use in conjunction with existing antenna assembly installations is effected by designing the radome to have a curved top portion, an outwardly diverging wall extending from the curved top portion, and an inwardly diverging wall extending from the outwardly diverging wall down to the base portion of the radome.
This invention features a low radar cross section radome comprising a lower inwardly diverging cone portion; an intermediate outwardly diverging cone portion on the lower inwardly diverging cone portion; and a curved top portion on the intermediate outwardly diverging cone portion.
In the preferred embodiment, the divergence angle of the lower cone portion is between 12° and 15° and the divergence angle of the intermediate cone portion is between 25° and 35°. Typically, the divergence angle of the intermediate cone portion is 10° greater than the divergence angle of the lower cone portion. Also in the preferred embodiment, the outer surface of the radome is smooth and continuous and the curved top portion is spherical in shape.
The low radar cross section radome of this invention has a lower inwardly diverging wall; an intermediate outwardly diverging wall extending upwards from the lower inwardly diverging wall; and a curved top portion on the intermediate outwardly diverging wall. In the preferred embodiment, the divergence angle of the lower inwardly diverging wall is between 12° and 15° and the divergence angle of the intermediate outwardly diverging wall is 10° greater than the divergence angle of the lower inwardly diverging wall.
A low radar cross section radome in accordance with this invention features a lower inwardly diverging portion; an intermediate outwardly diverging portion extending upwards from the lower inwardly diverging portion; and a top portion on the intermediate outwardly diverging portion.
REFERENCES:
patent: 4872019 (1989-10-01), Chow et al.
patent: 5757327 (1998-05-01), Yajima et al.
patent: 5828339 (1998-10-01), Patel
patent: 6191753 (2001-02-01), Ellis et al.
Chang Yueh-Chi
Rossman Court E.
Iandiorio & Teska
Le Hoang-anh
Raytheon Company
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