A Compact Dual-Band Bandpass Filter with Flexible Band Control and Simple Layout

A compact-size dual-band bandpass filter (BPF) with flexible band control and simple layout has been proposed in this paper. By employing the distributed coupling technique, each of the passbands can be independently designed based on the coupling coefficients and external quality factors. For a demonstration, a microstrip BPF operating at 0.7 GHz and 0.9 GHz with third-order Chebyshev bandpass response was designed and fabricated. Measured results are found in good agreement with the simulated ones.