Annular resonant structures and their uses as microwave filters

Recent trends in the development of microwave integrated circuits have tended to evolve systems with microstrip or triplate interconnexions between the active sections. It is thus desirable that any components incorporated into such microwave systems should be fully compatible with this general circuit form. A new configuration is described for the realization of a microwave band-pass filter. This configuration is particularly suitable for construction in `printed-circuit¿ form and is thus compatible with microstrip and triplate systems. Major advantages accrue from the attenuation characteristic of the filter which does not possess recurrent pass-bands at harmonics (or other overtones) of the design pass-band¿as do simple transmission-line structures. The filter is thus eminently suitable for use in frequency multipliers, parametric amplifiers and other systems in which the harmonic performance of the circuits is of paramount importance.