Elliptic-function lowpass filter with sharp cutoff frequency using slit-loaded tapered compact microstrip resonator cell

A novel slit-loaded tapered compact microstrip resonator cell to design a class of elliptic function compact lowpass filter with sharp skirt characteristics is proposed. Several cells are connected in series form to obtain an excellent lowpass filter. The bandwidth is enhanced and the size is reduced compared to conventional tapered resonators. The results of filter simulation with an EM-simulator and measurement show accurate attenuation at cutoff frequency. The proposed filters have compact and simple structures, small sizes, high selectivity, wide stopband, low insertion loss, etc; all these features are the requirements of wireless communication circuits. Measurement results show good agreement with the simulation.