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ABSTRACT This article presents a novel dual-band in-/anti-phase filtering power divider. The signals of the two output ports are symmetrically extracted from the resonator. Naturally, they are in-phase for even-mode passband but anti-phase for the odd-mode passband. The intrinsic reason is that a negative group delay (NGD) frequency band is presented between the two passbands, which opens a window for the change of the 180º phase differences. For demonstration, a dual-band filtering power divider is designed and measured based on the stub-loaded resonators (SLRs). Good agreements are observed between the measured and simulated results, showcasing small magnitude and phase differences in both passbands. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2626-2629, 2016 [ABSTRACT FROM AUTHOR]

A novel microstrip tri-band bandpass filter (BPF) based on stub-loaded triple-mode resonator is proposed. The open- and short-circuited stubs are asymmetrically loaded to a uniform impedance open-loop resonator, constructing a triple-mode resonator. Benefiting from the proposed asymmetrical loading scheme, the designed tri-band BPF not only possesses the controllable bandwidths of the three passbands, but also shows very wide stopband. Finally, a tri-band microstrip BPF with good performance is designed at 1.5, 2.57, and 3.83 GHz. Three transmission zeros near the passbands are obtained to improve the selectivity of the tri-band BPF. Meanwhile, the other transmission zeros produced in the stopband enhance the harmonic suppression level. The rejection level from 4.3 to 13.7 GHz is better than 20 dB. The measured results are in good agreement with the simulated data. [ABSTRACT FROM PUBLISHER]

In this paper, a novel end-loaded resonator is investigated and applied to design tunable bandpass fillter (BPF) and bandstop fillter (BSF). The novelty of the resonator lies in that two varactors are added to the two ends of the resonator, and then its resonant frequency can be bi-directionally tuned. As a result, the theoretical frequency tuning range can be significantly extended to approximately double that of the conventional tunable resonator. For demonstration, the proposed resonator is applied to design tunable BPF and BSF. As expected, the tuning ranges are 52.4% and 53.5% for the BSF and BPF, respectively. Good agreements can be observed between the simulated and measured results. [ABSTRACT FROM AUTHOR]

In this paper, a differential oscillator using parallel-strip line (PSL) with an inserted ground plane is proposed. Its two identical sub-oscillators on the opposite sides of a dielectric substrate, sharing a common PSL resonator and common ground plane in the middle of the substrate, generate anti-phase fundamental signals and in-phase second harmonics. At the common PSL output, the second harmonics are inherently cancelled out while the fundamental signals are well combined. The combination circuits, as required by the conventional differential circuits, are no longer needed. To further enhance the suppression of the second harmonics, the inset length of the ground plane into the PSL resonator is optimized to make the second harmonics be suppressed inside each sub-oscillator. [ABSTRACT FROM AUTHOR]

Presented is a novel multilayer dual‐mode dual‐band bandpass filter (BPF) using two identical microstrip cross‐slotted patch resonators placed back‐to‐back. The lengths of the slots on the patch resonator are designed to be different, which can be used to control the two degenerate modes individually so as to build two passbands of the proposed BPF. Two separated coupling paths for the two modes can be realised by the etched slits on the common ground plane of the two microstrip resonators. As a result, the coupling coefficients between the two resonators in each passband can be controlled independently. Furthermore, a new source‐load coupling scheme is incorporated in this design to enhance the stopband rejection and then improve the band‐to‐band isolation significantly. [ABSTRACT FROM AUTHOR]

A novel double-sided parallel-strip line (DSPSL) push-pull oscillator using two identical sub-oscillators on the opposite sides of a dielectric substrate is proposed. The two sub-oscillators, sharing a common DSPSL resonator and common ground in the middle of the substrate, generate out-of-phase fundamental signals and in-phase second harmonics. At the common DSPSL output, the second harmonics are cancelled out while the fundamental signals are well combined. By this design, an additional combiner at the output, as required by the conventional push-pull circuits, is not needed, which greatly reduces the circuit size and simplifies the design procedures of the proposed push-pull oscillator. [ABSTRACT FROM PUBLISHER]

A dual-band bandpass filter with high selectivity is presented. Using only a single set of asymmetric stepped-impedance resonators, this filter can create five transmission zeros near the passband edges and between the two passbands to improve the selectivity. Based on the proposed idea, a microstrip dual-band bandpass filter is implemented. [ABSTRACT FROM AUTHOR]