Compact microstrip broadband bandpass filter with harmonic suppression based on embedded resonators

A compact microstrip broadband bandpass filter with harmonic suppression is proposed. The bandwidth of the proposed wide-band filter is from 0.96 to 3.41 GHz and the 3-dB fractional bandwidth is 135%. Without increasing additional circuit size, a technique which involves embedded open stubs is used to suppress undesired high frequency harmonics. By cascading the embedded open stubs periodically in the connecting lines, the bandwidth of the stopband response can be enhanced. The frequencies of the open stubs can be arranged at the harmonic position for suppressing the undesired response.