Microwave Interference Techniques for Frequency Measurement and Filters

This paper reviews the application of microwave signal-interference techniques to interferometers for frequency measurement and filters. The microwave interference takes place when the input-signal components pass through two different electrical paths to be then recombined and produce an interference pattern. Path lengths define the interference-based power-transmission maximum and minimum, which are calculated to obtain the desired device frequency response. Reconfigurable interferometers, wide-band, and dual-band filters designed using interference principles are described in this overview paper.