Compact Cross-Coupled Bandpass Filter With Second and Third Harmonic Suppression

摘要

A compact cross-coupled bandpass filter with second and third harmonic suppression is proposed. Quarter-wavelength resonators and 0° feed structure are introduced to suppress second and third spurious responses. The measured return loss and insertion loss of the proposed filter with four quarter-wavelength resonators are better than 17.2 dB and less than 1.85 dB in the range of 3.42 GHz to 3.6 GHz, respectively, and the upper stopband is up to 3.7f0 with an insertion loss larger than 20.1 dB.