Method and device for protection against a jammer in a radio station comprising several change-over antennas and their use for the making of radiogoniometers

A protection device against a jammer in a radio station comprising several antennas which can be switched over to one or more reception channels, comprising, in each reception channel an attenuator having at least one diode to oppose passage of the signal in the reception channel, said attenuator having an attenuation ratio varying as a function of the time t according to a relation of the form 1-cos.sup.2 (.pi.t/2t.sub.1) where 2t, is a predetermined time interval, the opening of said attenuator being controlled by a generator of pulses with exponential fronts.

A protection device against a jammer in a radio station having several antennas which can be switched over to one or more reception channels, comprising at least one shunting circuit with two channels to execute delays or phase hopping in the reception channels according to a first relationship of the form 1- cos.sup.2 (.pi.-t/2t.sub.1) to perform the change-over in a first direction and according to a second relationship of the form cos.sup.2 (.pi.-t/2t.sub.1) to perform the change-over in a opposite direction, the shunting circuit being controlled by signals with exponential fronts.

A sequential radiogoniometer comprising:

• an array of antennas for generating high-frequency signals;
• a processing unit coupled to said antennas;
• means for conversion and shunting of the signals from the antennas, in series with a set of reception channels, said processing unit for controlling the change over of the array of antennas and the conversion and shunting circuits, to ensure the computation of the angle of arrival, of the electromagnetic waves at the arrays of antennas, with respect to a determined geographical direction of the space in which the array of antennas is located, said conversion and shunting circuit being formed by a set of delay lines coupled to the transmission channels through a hybrid coupler in quadrature and a change-over switch, wherein the change-over switch comprises a single or double shunting circuit with diodes to couple the outputs of the hybrid coupler in quadrature alternatively with the inputs of all the reception channels and to reduce spectral aliasing to the minimum, the change-over of the shunting circuit to the outputs of the coupler being done according to a first relationship of the form 1-cos.sup.2 (.pi.t/2t.sub.1) and a second relationship of the form cos.sup.2 (.pi.-t/2t.sub.1) the shunting circuit being controlled by signals with exponential fronts.