Differential attenuation and phase shift measuring system - uses separate antenna circuits for each polarisation plane, having divider circuit feeding local oscillator and shift measuring circuit

摘要

The differential attenuation and the phase shift between two RF waves with orthogonal polarisation are measured to determine propagation characteristics for telecommunications or radionavigation systems. A single transmitter and receiver are used to avoid measurement errors. A transmitter (12) emits a wave polarised at 45 degrees from an antenna (10). The wave components are received by a vertical (22V) and horizontal (22H) polarised antennas. The signals are routed, via dividers (24) and circulator (34), to an attenuation measuring circuit (30) containing a receiver and channel recorders to determine the difference in signal strengths. Part of each input signal passes via circulators (43) to frequency mixers (44) which are connected to the local oscillator (36) in the measuring circuit. The mixer outputs are applied to a phase measuring circuit (46).