A method of covert protection of important objects

Inventors

1. A method for covertly protecting important objects, which consists of emitting and receiving a radio signal using antennas covertly located near the surface of the earth in a controlled area, whereby, upon recording changes in the received radio signal, a message is generated about the appearance of an intruder, characterized in that, when emitting and receiving the signal, vertical pin antennas are used that are covertly installed near the boundaries along the length of the controlled area, which transmit and receive a narrowband radio signal in the frequency band of meter or decimeter waves, whereby a system of Fresnel zones is formed between the radio signal emitter and the receiver, and the appearance of an intruder in the controlled area is monitored by the occurrence of high-frequency components in the received signal, recorded by analyzing the frequency spectrum of the received signal.
2. The method according to paragraph 1, characterized in that a signal with a frequency of 159-161 MHz is used as a narrowband radio signal in the meter wave range.
3. The method according to paragraph 1, characterized in that signals with frequencies of 433 MHz or 866 MHz are used as a narrowband radio signal in the decimeter wave range.