Design of narrowband bandpass filter on coplanar waveguide using spiral slots

Abstract

A configuration for a miniaturized band-pass filter on a coplanar waveguide (CPW) is proposed in this communication. Parametric studies conducted for various geometrical parameters suggest that the frequency response of the filter is strongly related to that of the spiral slots. A a series gap on the center conductor of the CPW changes the overall response of the device. For validation of these concepts, a bandpass filter operating at about 3.5GHz has been designed, fabricated and tested. Experimental results show good agreement with electromagnetic simulations. The design takes up an area of approximately 0.1λ0 × 0.1λ0.