Self-adaptive amplitude equalizer for digital microwave beams

Operational principles of a self-adaptive equalizer for the automatic correction of amplitude/frequency distortions created by the multipath propagation of a digital microwave beam are presented. The amplitude/frequency and phase/frequency distortions encountered due to multipath propagation, particularly in high-bit-rate microwave channels, are reviewed, and advantages of IF self-adaptive amplitude equalization in such situations are pointed out. The principles of self-adaptive amplitude correction at intermediate frequencies are then examined, with attention given to the servoloop and corrective filter circuits, and the integration of such a corrector within a microwave receiver is discussed. Results of a laboratory simulation of the operation of an equalizer in the presence of simulated multipath propagation are presented which demonstrate a dramatic improvement in signal reception in space diversity reception systems.