Microwave landing system with protection against jamming
First Claim
1. A microwave landing system comprising two ground stations, transmitting respectively angular messages of azimuth and elevation, each angular message being constituted by a preamble followed by an angular function, each station comprising:
- a sector antenna transmitting said preamble of said angular function;
a scanning beam antenna transmitting said angular function and having a gain higher that the sector antenna gain;
means for superimposing, in phase, the radiation pattern of said sector antenna and the radiation pattern of said scanning beam antenna, the latter pointed in a predetermined direction during the entire transmission of said preamble and the superposition of radiation patterns occurring successively in several chosen directions which in their entirety cover the complete sector radiation pattern, so as to reinforce the gain, in a given sector, of the sector radiation pattern of said sector antenna with regards to the normal gain of said sector pattern.
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Accused Products
Abstract
In a microwave landing system or MLS, the bearing and/or elevation angular messages are in two parts a preamble transmitted by a sector antenna and a specific message transmitted by an electronic scan or scanning beam antenna. As the gain of the sector antenna is below that of the scanning beam antenna, the preamble is much more vulnerable to scanning than the message.
According to the invention, a preamble is transmitted, which is reinforced in a narrow angular sector and movable so as to cover the sector covered by the sector antenna by superimposing the radiation patterns of the sector antenna and the scanning beam antenna in said direction.
13 Citations
8 Claims
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1. A microwave landing system comprising two ground stations, transmitting respectively angular messages of azimuth and elevation, each angular message being constituted by a preamble followed by an angular function, each station comprising:
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a sector antenna transmitting said preamble of said angular function; a scanning beam antenna transmitting said angular function and having a gain higher that the sector antenna gain; means for superimposing, in phase, the radiation pattern of said sector antenna and the radiation pattern of said scanning beam antenna, the latter pointed in a predetermined direction during the entire transmission of said preamble and the superposition of radiation patterns occurring successively in several chosen directions which in their entirety cover the complete sector radiation pattern, so as to reinforce the gain, in a given sector, of the sector radiation pattern of said sector antenna with regards to the normal gain of said sector pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification