| 摘要 |
<p>The present invention relates to the field of passive VHF-UHF radars. It relates more particularly to the construction of omnidirectional VHF-UHF antennas, with wide passband, that can operate in an array without adversely affecting their radiation patterns. The invention consists of a dual-band antenna structure operating on two sub-bands of wide frequencies, and consisting of radiating elements forming a sub-antenna with minimum diffraction operating in the high sub-band, UHF, and a sub-antenna with minimum diffraction operating in the low sub-band, VHF, each element being brought into service or taken out of service separately as a function of the sub-band utilized. The output of the antenna is linked to the input of an amplifier with low wide band noise, placed as close as possible and exhibiting a high-impedance input and an output equal to the impedance of the transmission line through which it is linked to the receiver, the sub-antenna dedicated to the low sub-band comprising low-pass filters arranged so as to prevent the operation of this element when the element dedicated to the high sub-band is in service.</p> |
