A Remotely Switched Passive Null-Peak Network for Animal Tracking and Radio Direction Finding

Abstract

A remotely switched null-peak network for combining RF signals from dual antenna arrays used for radio direction finding and animal tracking is described. The design is based on a balanced 50-Ohm coaxial bridge, which provides a difference (null) and summed (peak) output from two parallel antennas to the receiver. Reed relays activated through the receiver cable permit the network to be switched between peak or null modes of operation from the receiver, without the need for long dual cable runs from the antenna. The bridge presents a nominal 50-Ohm impedance at all terminals.