Low-Noise Microwave Active Filters in Planar Realizations

Design and results of active filters based on low-loss suspended stripline filter resonators and MeSFET gain blocks realized in microstrip are presented. The coupling between filter resonators and microstrip gain blocks is performed electromagnetically acting, at the same time, as matching structures for input and output of the transistor. In this way, very low noise active filter circuits with a single gain stage and two stages at 10 GHz as well as a single stage 35 GHz active filter were realized.