A Compact Quint-Band Bandpass Filter with High Selectivity Using Uniform Impedance Resonators (UIRs)

This paper proposes the design of quint-band bandpass filter with high out-of-band selectivity. The filter is created by using multimode stub loaded uniform impedance resonators (UIRs) which are embedded in order to obtain the multipath transmission of signal. In terms of the four propagation paths composed by UIRs, four passbands are produced and the fifth passband is generated based on the feeding structure which serves as a couple of cross-shaped resonators. Besides, the extremely symmetrical structure is analyzed along with source-load coupling and electric/magnetic coupling are generated for introducing transmission zeros (TZs). Four different transmission paths can produce phase differences. Due to the aforementioned mechanism, thirteen TZs are produced and the selectivity out of the quint-band gets improved greatly. Additionally, the miniaturization of filer is realized and low insertion losses, high stopband suppression as well as excellent multi-band selectivity are also obtained. Here, the simulated graph of S21 are also exhibited.