We described in French patent No. 79 02918 of Feb. 5, 1979, (i.e., U.S. Pat. No. 4,344,077) a method which makes it possible to eliminate the jamming activities of jammers that transmit towards a radar antenna which aim direction is shifted in relation to the straight line that connects the antenna to the jammer. This method rested on the fact that by using an appropriate make-up filter and conveniently placed in front of the antenna, we could modify the amplitude of the antenna radiation pattern secondary lobes especially by generating "dips" that we could shift in angular fashion according to the aim direction of the antenna. By making the orientation of the pattern dips coincide with the transmitting direction of the jammer (in relation to the antenna), we could thus eliminate the jamming effect.
The same patent describes a method that makes it possible consequently to sense the position of a jammer by assessing the point at which jamming no longer represents any significant problem. Such a search by "negative effect" is fairly delicate and not very accurate, especially in view of the residual noise level of the antenna.
In the patent application No. 81 18674 (U.S. Pat. No. 4,518,966) of Oct. 5, 1981, we described a filter that allows the generalization of inhibitive activity against jammers for any hyperfrequency antenna with any polarization direction, whereas in the above mentioned patent No. 79 02918, attenuation was only possible to the extent that the hyperfrequency antenna would transmit a linearly polarized wave. In the most recent patent application, there was no description for a specific method to search and assess the position of a jammer, being referred for this search to the "negative effect" procedure that was envisioned in the previous application.
USPTO Backgrounds
USPTO Backgrounds