| 摘要 |
A self contained electronic theft detection apparatus comprising a housing from which a rigid tubular transmitter antenna loop (32) extends; and a wire loop receiver antenna extends the transmitter antenna loop. The transmitter antenna (32) is provided with a capacitor (C54) with which it resonates at the frequency of responder elements to be detected and the transmitter antenna is supplied with sharp voltage pulses from a pulse forming circuit (66) and a power amplifier (68) which cause the antenna to resonate in a rapidly decaying manner. |
