Dual-Band Bandpass Filter Based on Suspended Coplanar Waveguide-Microstrip Hybrid

In this paper, a new transmission line structure of suspended coplanar waveguide-microstrip (SCPW-MS) hybrid with broadside coupling which is composed of a coplanar waveguide (CPW) on the upper layer and a microstrip on the lower layer of the main circuit is proposed, and an insertion loss of no more than 0.4 dB in frequency band of DC to 7 GHz has been demonstrated. Then a new type of dielectric resonator loaded dual-band bandpass filter with working frequency of 1.06/3.4 GHz, fractional bandwidths of 28.3%/17.6%, and insertion loss of no more than 1.3 dB has been developed with the hybrid broadside coupled transmission line. The dual-band bandpass filter is mainly realized by a new dual-mode resonator, and each passband is composed of dual-resonant modes. The bandwidth of the second passband is widened by introducing a dielectric resonator (DR) and a stepped impedance resonator (SIR). Advantages of easy hybrid integration, low loss and self-packaging have been demonstrated for both of the presentations.