Level interrupt free HF transmission between vehicle and line - using two antennae fed via high and low pass filters respectively giving opposite phase shifts

摘要

The radio communications system uses several, e.g. two aerials located one behind the other in the direction of travel of the vehicle. These aerials are inductively coupled to a two-wire line laid along the road and having its wires crossing over at intervals. The signals being sent are passed via e.g. two parallel transmit channels to the two aerials. The first channel contains a low pass filter, and amplifier and a bandpass filter. The second channel contains a high pass filter, an amplifier and a bandpass filter. The phase shifts in the bandpass filters and amplifiers are the same for both channels.