Miniaturized Dual-Band Bandpass Filter using Short Stub-Loaded Dual-Mode Resonators

A novel miniaturized dual-band bandpass filter using two sets of short stub-loaded dual-mode resonators (SSLDMRs) is presented in this paper. It has been implemented with two parallel transmission paths for two specific passbands, which is convenient to design single-band independently. Each of them using the proposed SSLDMR results in respective passband. Meanwhile, it is easy to control the bandwidth of each passband by changing even-mode resonant frequency of the corresponding SSLDMR. Moreover, one set of SSLDMRs is embedded inside of the other one for the size compactness, which can further miniaturize the dimensions of the overall structure. To improve the selectivity and achieve a high out-of-band rejection, the source-load coupling is utilized to create four transmission zeros on either side of both passbands. The simulated and measured results are presented and show good agreement.