Search

This letter proposes a wide-range reconfigurable bandpass filter (WRBPF) based on the cross-shape triple-mode resonator. Varactor diodes and switching diodes are utilized at the ends of the resonator and the positions of external coupling, which combines the two working modes of the low-frequency band and high-frequency band, greatly broaden the tunable range of the center frequency ($f_{0}$). When the 3-dB bandwidth of WRBPF is 180 MHz, $f_{0}$ can be adjusted from 0.78 to 1.93 GHz, and the relative adjustment range is 84.9%. When $f_{0}$ is 1.355 GHz, the absolute bandwidth can be adjusted from 110 to 950 MHz, and the relative bandwidth adjustment range is 8.1%–70.1%. Moreover, the circuit size of WRBPF is only $0.29\,\,\lambda g\,\,\times 0.22\,\,\lambda g$. The experimental results show that WRBPF has not only a simple structure but also an excellent performance. [ABSTRACT FROM AUTHOR]

A channel-continuous triplexer (CCT) with multiple transmission zeros (TZs) is designed and processed by cascading the high-pass filter (HPF) and low-pass filter (LPF) through the matching branches. The CCT is realized based on the substrate integrated suspended line (SISL) technology. The out-of-band suppression (OBS) and roll-off rate (ROR) of CCT are improved by the TZs introduced by cross-coupling lines between the nonadjacent branches in the HPFs and high-low impedance microstrip line T junction in LPFs. The experimental results show that CCT covers 4–7 GHz by three continuous bandwidth-identical passbands with the fractional bandwidths (FBWs) of 22.2%, 18.1%, and 15.3%, respectively. The insertion loss within three passbands is less than 1.7 dB, the out-of-band rejection is more than 50 dB, and the ROR is greater than 200 dB/GHz. [ABSTRACT FROM AUTHOR]

A novel compact high-temperature superconducting low-pass filter (LPF) with an ultrawide stopband, excellent out-of-band rejection, and a low insertion loss is presented. This filter consists of a four-order LPF constructed by four interdigital hairpin stepped-impedance resonators (IHSIRs) and two pairs of radial stubs (RSs) in the input and output ports of the filter. The four-order IHSIR LPF brings transmission zeros for a high selectivity, and the RSs exhibit a characteristic of extending the LPF’s stopband effectively. The proposed LPF with cutoff frequency $f_{c}$ at 3 GHz is implemented on a 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a 30-dB harmonic suppression from $1.08f_{c}$ to $7f_{c}$ , a steep roll-off of 197.1 dB/GHz, and an in-band insertion loss less than 0.13 dB. Moreover, the LPF possesses a miniaturized size of $0.21\lambda _{\text {gc}} \times 0.03\lambda _{\text {gc}}$. [ABSTRACT FROM AUTHOR]

This letter presents a new multimode ring resonator ultrawideband (UWB) bandpass filter by loading a microstrip line on the vertical symmetrical plane of a ring resonator and a pair of stepped-impedance open stubs at the center of this microstrip line. Five modes are allocated within UWB band, and a pair of transmission zeros are introduced to improve the passband selectivity. By adopting the parallel-coupled lines, not only suitable external coupling is achieved, but also the performance of upper stopband is improved. This quintuple-mode high-temperature superconducting UWB filter is designed on a 0.5-mm-thick MgO substrate with double-sided YBCO films. The measured results show that 3-dB bandwidth covers 1.57–6.51 GHz, the return loss is better than 10.70 dB, the out-of-band rejection is greater than 24.75 dB in the lower stopband, and the upper stopband with 20-dB attenuation level is extended to about 9 GHz. [ABSTRACT FROM AUTHOR]