| 摘要 |
<p>The transponder has a receiving antenna (1) to receive a signal transmitted by a Doppler radar, and a transmitting antenna (2) to retransmit the signal. The signal received by the receiving antenna is amplitude-modulated before retransmitting by the transmitting antenna to produce a variation of the radar cross-section of a target i.e. aircraft, where the variation triggers a frequency shift between the signal transmitted and the signal received by the radar comparable to a Doppler echo. A low noise amplifier (21) is connected between the receiving antenna and the transmitting antenna. An independent claim is also included for a target location system.</p> |
