Microwave filter

Filter technologies

In general, most RF and microwave filters are most often made up of one or more coupled resonators, and thus any technology that can be used to make resonators can also be used to make filters. The unloaded quality factor of the resonators being used will generally set the selectivity the filter can achieve. The book by Matthaei, Young and Jones provides a good reference to the design and realization of RF and microwave filters. Generalized filter theory operates with resonant frequencies and coupling coefficients of coupled resonators in a microwave filter.