主题：【原创】决定二战胜负的科技 -- 正宗鲁皮皮

The device described in the WWII patent works as follows: The shell contains a micro-transmitter which uses the shell body as an antenna and emits a continuous wave of roughly 180–220 MHz.

As the shell approaches a reflecting object, an interference pattern is created. This pattern changes with shrinking distance: every half wavelength in distance (a half wavelength at this frequency is about 0.7 meters), the transmitter is in or out of resonance. This causes a small oscillation of the radiated power and consequently the oscillator supply current of about 200–800 Hz, the Doppler frequency.

This signal is sent through a band pass filter,amplified, and triggers the detonation when it exceeds a given amplitude.