Compact microstrip bandpass filter with sharp transition bands

The design of a two-pole compact microstrip bandpass filter is presented. The filter consists of only one miniaturized center-stubbed half-wavelength resonator and tapped-line input/output ports, and exhibits transmission zeros at both sides of the passband. Therefore, it is very compact, and provides sharp transition bands. The measurement results of filters designed at 4.4GHz are given to validate the theory.