Waveguide Switchable Bandstop and Bandpass Filters Using RF MEMS Switches

Waveguide switchable bandstop and bandpass filter designs are demonstrated in this paper. The designs are based on the design of rectangular waveguide that has switching planar bandstop resonators inserted on the sidewall. These switchable bandstop resonators consist of two identical metal patches separated by switching elements. The switching elements can be of RF MEMS or semiconductor transistor type. These resonators allow electrically switching of the waveguide while providing close to ideal on-state insertion loss and narrow stop band during off-state. These switches permit the switchable bandstop and bandpass filters design. The concept is demonstrated for a switchable five-pole bandstop filter and a switchable three-pole bandpass filter, both at the centre frequency of 14.25 GHz and for 500 MHz bandwidth.