Wanchun Tang

This paper proposes a novel wideband bidirectional absorptive common‐mode filter based on the modified coupled‐C slot resonators. Each coupled‐C slot resonator is constructed by etching two asynchronously tuned C‐shaped slots with opposite direction. On this basis, single or two lumped resistors are added on the middle symmetric plane of coupled‐C slot resonator to achieve unidirectional or bidirectional common‐mode absorption. Furthermore, the corrugated slot stubs are introduced in coupled‐C slot resonator to improve the common mode absorption performance. Subsequently, a bidirectional absorptive common‐mode filter is proposed with wide absorption band and high absorption ratio by successively cascading unidirectional, bidirectional and unidirectional coupled‐C slot resonators. As a demonstration, a prototype of the proposed common‐mode filter has been fabricated and measured. The measured results show that the proposed common‐mode filter could maintain good transmission of differential signals below 6.2 GHz. In addition, common‐mode transmission and reflection coefficients could be kept less than −10 dB from 2.6 to 6.6 GHz simultaneously with 87% fractional bandwidth, demonstrating the good common‐mode absorption performance.

In this study, a novel expression for the time‐domain (TD) reflection coefficients of ultra‐wideband (UWB) pulses on the surface of Debye medium surface is proposed, which includes both vertical and horizontal polarization cases. Compared to previous research, this new analytical expression eliminates convolution operation and Bessel function, significantly improving computational efficiency while maintaining comparable accuracy and avoiding singularity under certain conditions. Through detailed theoretical derivation and numerical simulation, the effectiveness of the new expression has been verified. Numerical results indicate that the new expression not only simplifies the calculation process, but also greatly reduces the computation time and enhances the stability, providing a new theoretical tool for analyzing the propagation characteristics of UWB pulses on Debye medium.

This letter proposes a wideband high selective on-chip bandpass filter (BPF) implemented on GaAs substrate integrated passive device (IPD) technology. Introducing lumped elements outside the resonator and coupling them with the resonator can introduce three transmission zeros (TZs). These three TZs are elaborately generated to enhance frequency selectivity and improve stopband rejection level. Moreover, it leverages high-quality-factor lumped elements, significantly bolstering the circuit’s resonance capacity. When wideband performance is necessary, using the Chebyshev principle for design allows achieving the desired bandwidth. To validate this design approach, a BPF centered at 3.8 GHz was simulated, fabricated and measured using GaAs IPD technology, showing promising applications in integrated circuit designs.

The authors express gratitude to Prof. Park for providing an alternative simplification of the isolation resistance expression in his comments, referred to as the corrected version, as well as presenting different simplified versions for impedance expressions $Z_{A6}$ and $Z_{A7}$ . However, the claimed corrected version of the isolation resistance is just another simplification of the isolation resistance expression we provided earlier, and they are mathematically equivalent within the context of the original text.

In this article, a new design of dual-wideband filtering power divider (FPD) based on genetic algorithm (GA) is proposed. In the three-port design, a set of data structures are constructed to describe the corresponding connection methods between the basic units and their electrical parameters. Then, to obtain the optimal data structure to meet the FPD specification, the GA is used to find the optimal design topology and electrical parameters, including isolation resistors. To validate the design concept, a prototype centering at 2.1 and 6.6 GHz with 3-dB fractional bandwidths of 75.2% and 22.9% is designed, fabricated, and tested. Both simulation and experimental results are provided with good agreement.

The authors of [1] , regret that due to typing and mathematical errors in the proof, a few corrections need to be made to the letter. Despite these errors, the main contributions as well as the conclusions are correct.

In this letter, a high-selective dual-band filtering antenna for millimeter-wave application is first proposed based on half-mode gap waveguide (HMGW) quadruple-mode resonator (QMR). Four resonant modes are simultaneously excited within a single cavity following the transversal hybrid electromagnetic coupling topology, thus forming dual-passband filtering characteristics. Three radiation nulls are generated on both sides of two passbands due to the created bypass coupling and can be controlled independently. A stacked radiating cavity with shared-aperture provides uniform polarizations for dual frequency application. For experimental validation, 3-D Multi-Jet-Printing (MJP) technology was used to fabricate prototypes integrally, significantly reducing the assembly loss. The final measured results agreed well with the simulated ones.

This article proposes a new design approach for filtering crossovers featuring wide-stopband and dual-band characteristics based on mixed substrate integrated waveguide (SIW) cavities. The degenerate orthogonal modes in multimode full-mode SIW (FMSIW) square cavities are fully exploited as the cross-unit of dual channels for cross-transmission and good isolation. By developing proper coupling topology between multiple quarter-mode SIW (QMSIW) cavities and the FMSIW cavity, a compact wide-stopband filtering crossover is presented with more than $-$ 20 dB stopband rejection up to 2.11 $f_{0}$ . In order to construct a dual-band filtering crossover topology which has not been reported before, half-mode SIW (HMSIW) cavities are explored to cooperate with the FMSIW cavity, thus leading to a satisfactory dual-passband crossover response for the first time. To validate the design concept, a wide-stopband and a dual-band filtering crossovers are designed, fabricated, and measured. Results exhibit excellent filtering performance and good channel-to-channel isolations over an ultrawide frequency band.

In this article, a new approach for designing 3-D printed single-and dual-band filtering rat-race couplers based on hemispherical cavities is presented, for the first time. By constructing two types of multiplexing multimode topologies in dual-cavity configurations, both single-and dual-band filtering rat-race couplers are developed. In these designs, a pair of TM $_{201}$ degenerate modes form the passband for single-band operation, while dual-band operation is realized by exciting an additional pair of TE $_{101}$ degenerate modes. Due to the natural $E$ -field distributions of these modes, the desired 0 $^{\circ}$ and 180 $^{\circ}$ phase differences and isolations can be realized between output ports without additional matching circuits. By elaborately placing the internal coupling slots and input–output ports, desired filtering responses and phase requirements can be flexibly attained for both single-and dual-band filtering rat-race coupler designs. For demonstration, two prototypes are well implemented as monoblock circuits using 3-D-printing technology. Compared with the up-to-date designs, the proposed works exhibit the merits of compact size, high $Q$ -factor, lightweight, good single-and dual-band filtering responses with controllable bandwidths and center frequencies, nice phase difference characteristics as well as flexible extendable topologies.