very broadband active antenna for passive radar.

The invention relates to the field of VHF-UHF passive radars. It relates more particularly achieving VHF-UHF omnidirectional antennas, bandwidth, network operable without altering their diagrams rayonnement.L'invention consists of a dual band antenna structure, operating on two sub wide frequency bands, comprising radiating elements forming a diffraction minimum slot antenna operating in the high sub-band, UHF, and a minimum diffractive sub-antenna operating in the lower subband, VHF, each member being on or off separately operated depending on the subband. The output of the antenna is connected to the input of a low noise amplifier broadband placed closer and having a high impedance input and an output equal to the impedance of the transmission line through which it is connected to the receiver, the sub-antenna dedicated to the low subband having low-pass filters arranged to prevent operation of the element when the element dedicated to high subband is in use.