A microstrip low-pass filter with sharp roll-off and excellent suppression in both the near- and far-stopbands is proposed. The design incorporates a stepped-impedance hairpin-type resonator (SIHTR) along with a pair of asymmetric T-shaped resonators (TSRs). While the SIHTR offers a tunable 3 dB cutoff frequency and roll-off rate (ROR), its near-stopband suppression degrades at higher ROR values. To address this limitation and further extend the stopband bandwidth, two TSRs with distinct resonant frequencies are positioned at the input and output ports. By fixing their resonant frequencies and fine-tuning their stopband characteristics, the overall suppression bandwidth and stopband attenuation are significantly enhanced. The proposed filter features a compact layout, high selectivity, a wide stopband, and excellent out-of-band suppression performance. Measured results demonstrate an insertion loss of less than 1 dB and a return loss of greater than 15.1 dB in the passband from DC to 7.5 GHz. The 3 dB cutoff frequency is 8.23 GHz, and the transition band is 34.58 dB/GHz from -3dB to -40dB. In the stopband, attenuation exceeds 31.5 dB across the frequency range from 9.17 GHz to 40 GHz.

To address the interference of common-mode noise on signal transmission, this paper presents a balanced filter design suitable for L-Band communication systems, featuring high common-mode (CM) rejection, compact size, and low insertion loss. By employing a slow-wave structure metal shielding enclosure combined with cryogenic cooling technology, the proposed design significantly enhances both CM suppression performance and differential-mode (DM) transmission performance. Experimental results demonstrate that the filter achieves 38 dB CM rejection within the operational band of 1.47-1.53 GHz while maintaining good DM frequency stability, with insertion loss ranging from 0.68 dB to 0.87 dB. Furthermore, to overcome measurement inaccuracies caused by additional components in conventional two-port vector network analyzer configurations for balanced filters, this paper develops an improved testing methodology. This method reduces testing errors to below 0.1 dB across the differential passband, demonstrating good measurement accuracy compared to existing methods.

A K-band millimeter dual-band superconducting filter with uneven coupled step-impedance resonators (SIRs) and stub-loaded combining network is proposed in this paper. The novel uneven internally coupled SIR introduces a notch to the classical internally coupled SIR, enhancing the Q-factor for narrow-band filter design. The performance of the uneven coupled SIR is theoretically analyzed, and two single-passband superconducting filters based on the proposed resonator are designed and demonstrated its high Q-factor. A novel stub-loaded combining network is then investigated theoretically to integrate the two single passband filters into a dual-band filter. To validate the design concept, a dual-band superconducting filter is designed on a magnesium oxide (MgO) substrate using the yttrium barium copper oxide superconducting film. The measured results reveal insertion losses of 0.91-1.2 dB of the first passband at 24.21-24.41 GHz with the bandwidth of 0.82% and 0.43-1.3 dB of the second passband at 24.67-25.2 GHz with the bandwidth of 2.12%, respectively. Both passbands exhibit return loss levels exceeding 8 dB, a maximum out-of-band suppression of approximately 65 dB, and a rejection level of about 35 dB between the two passbands.

This paper proposes a linear phase superconducting bandpass filter and its corresponding parameter extraction method based on an enhanced multilayer perceptron (MLP) algorithm. The filter is implemented using internally coupled stepped impedance resonators, for which a new equivalent circuit model is introduced to theoretically analyze the resonance condition. Beginning with a designed coupling matrix, a six-resonator initial circuit layout is constructed by incorporating in-phase cross-coupling to achieve group delay equalization and ensure a linear phase response. A training dataset is generated using randomly perturbed versions of the designed coupling matrix and their corresponding S -parameters. An enhanced MLP algorithm, which is augmented with Fourier-transformed input S -parameters, a self-attention mechanism, and gradient-weighted class activation mapping, is employed to inversely model the nonlinear mapping from S -parameters to the underlying coupling matrix. The physical circuit layout is manually tuned based on the difference between the extracted coupling matrix and the designed one. After five iterative cycles of parameter extraction and layout tuning, the optimized superconducting bandpass filter, is fabricated using yttrium barium copper oxide (YBCO) thin films patterned on both sides of a magnesium oxide (MgO) substrate. Cryogenic measurements at 77 K, where the YBCO films are superconducting, demonstrate that the superconducting filter operates over 4.75–5.0 GHz, achieving an insertion loss of 0.08–0.62 dB, a minimum return loss of 13 dB, and out-of-band rejection exceeding 50 dB. The group delay variation remains within ±1 ns across 80% of the passband, indicating excellent phase linearity.

A miniaturised millimetre-wave bandpass filter chip based on the integrated passive device (IPD) process for 5 G new radio is proposed in this paper. Two techniques are utilised to minimise the circuit footprint. Firstly, the innovative edge self-coupled split ring resonator (ES-SRR) is proposed, which incorporates a self-coupled effect by narrowing the gap between the vertical microstrip line and the two split stubs. The theoretical model of the ES-SRR is examined to identify its resonating characteristics. Secondly, the magnetic dominant mixed-coupling structure is implemented in the planar filter by meticulously adjusting the resonator line widths. This configuration generates two transmission zeros at each side of the passband. To demonstrate their effectiveness, a sixth-order bandpass filter, operating within the frequency range of 24.25-29.5 GHz, is simulated and fabricated using 100-mu m-thick GaAs IPD technology. Experimental results reveal an insertion loss of 2.95 dB and a minimum return loss of 17 dB, achieving a fractional bandwidth of 21%. Notably, the filter exhibits two transmission zeros at 21 GHz and 33 GHz with rejection levels of 55 dB and 60 dB, respectively.

This paper introduces a low-complexity vector magnetic field solution based on a diamond NV ensemble. Firstly, the bias magnetic field of the diamond NV colour centre equifrequency difference optical detection magnetic resonance (ODMR) spectrum is adjusted, and the conversion matrix is derived by utilising the projection of the external magnetic field on the NV axis of the diamond, which exhibits an equal probability distribution, and the preset magnetic field to be measured. The vector magnetic field information solution model is then constructed. Subsequently, the pulse timing system is employed to regulate the antenna, enabling the generation of microwave pulse signals with uniform timing and frequency difference. Finally, the accuracy of the vector magnetic information solution is verified by the established model and the entire detection system. The final vector magnetic field detection exhibits the amplitude difference of coil calculation results is less than 3.6%, and the angle difference of coil calculation results is less than 1.8◦. In comparison to alternative methodologies, the amplitude and angle discrepancies in coil calculation outcomes are simultaneously minimized.

This paper proposes an air-filled substrate integrated waveguide (AFSIW) bandpass filter with a miniaturized non-resonant node (NRN). The NRN structure is introduced between the three resonators, and its size is smaller than the resonator size, which can realize the NRN structure's miniaturization and reduce the model's size. The NRN size of this filter is 41% of the NRN size of the existing AFSIW filter. This filter also introduces a transmission zero (TZ) above the passband. The measured results show that the filter's center frequency is 20.73 GHz, and the bandwidth is 0.86 GHz. The insertion loss in the passband is 0.95 dB, and the return loss is better than 23 dB. Due to the TZ in the upper stopband, the AFSIW filter obtained good selectivity.

The researches on dispersion profiles are prominent for nonlinear optics, optical communication and spectroscopy. A highly birefringent, low-loss fiber is designed in this article by introducing a double elliptical air hole in the x-direction. Furthermore, the influence of birefringence and dispersion with the structure parameters and wavelength have been demonstrated. To realize the application in nonlinear optics, we have filled the fiber core with SC2 and the effective mode area and nonlinear coefficient have been calculated to verify the performance in nonlinear applications. We consider that the proposed bias-preserving fiber is highly forward-looking in the design of high birefringence fiber and dispersion-compensating fiber when applicated in nonlinear fiber optics and optical communications.

Mechanical-electromagnetic integrated design has great potential in the development of electromagnetic shielding equipment for military use. In this study, Al2O3/SiO 2 ceramics with triply periodic minimal surfaces (TPMSs) were fabricated using digital light processing (DLP) technology. The preparation of SiO 2 and Al2O3 powders is vital for DLP because minimal aggregates or sedimentation in the ceramic paste is required. Debinding and sintering programs were developed to prevent defects in the designed microstructure. The interfacial characterization demonstrated that the surfaces of the sintered ceramics were compact and smooth. The compression strength of the TPMS ceramic with a volume fraction of 50% was 24 MPa, which is relatively good among additively manufactured cellular ceramics. The TPMS structures also exhibited significant electromagnetic interference (EMI) shielding effectiveness in the X-band (2 to 18 GHz), and the shielding performance was adequate to meet the demands of electromagnetic shielding materials. Additive manufacturing of Al2O3/SiO2 ceramic with TPMS architectures was successfully achieved by considering the mechanical-electromagnetic integration.

A novel miniaturized evanescent-mode substrate integrated waveguide (SIW) bandpass filter with D-shaped slotlines for spurious harmonic suppression is proposed in this letter. Closed-form equations for the proposed evanescent-mode SIW cavity are summarized and two D-shaped slotlines are etched together as a pair by the face-to-face style to obtain the designed lowpass feature, which could be utilized to improve the out-of-band spurious harmonic rejection level. To validate the feasibility of this method, a miniaturized evanescent-mode SIW filter with D-shaped slotlines is designed and measured. The measured results show that this filter operates at 1.05 GHz with 2.4 dB insertion loss and 3.8% bandwidth. The out-of-band spurious rejection is lower than 16 dB up to 11 times of the higher cutoff frequency of the passband. All test results are in good agreement with the simulation results.

This paper considers the performance of non-orthogonal multiple-access (NOMA) with full-duplex (FD) relaying system in the presence of two practical undesirable defects, namely channel estimation error (CEE) and in-phase/quadrature-phase imbalance (IQI). Specifically, in the proposed NOMA with FD relaying system, the exact expressions of outage probability (OP) for the considered two users have been derived firstly. Then, the corresponding optimal power allocation coefficients for minimizing the OP of the dual users are obtained. Finally, the approximate expression of the ergodic sum rate (ESR) for the system is presented. Simulation results demonstrate that: (1) NOMA with FD relaying system can achieve superior outage performance in comparison with NOMA with Half-duplex (HD) relaying system at low Signal-to-noise ratio (SNR), but the circumstance is exactly the opposite at high SNR; (2) IQI and CEE would result in performance degradation, and must be seriously considered while designing NOMA with FD relaying systems.

In this paper, we propose a novel spectrum-efficiency (SE) optimization scheme for amplify-and-forward (AF) cooperative relaying systems based on non-orthogonal multiple-access (NOMA). In this network, a weighted-sum-minimum mean-squared-error (WSMMSE) method is utilized to transform the original non-convex optimization problem into a tractable optimization problem. Then, the relay beamforming-matrix (BM) and the power-allocation (PA) coefficients are alternately optimized by use of the iterative beamforming method and the Lagrange-multiplier (LM) method subject to the quality-of-service requirements. Monte Carlo simulation results verify that our proposed new scheme can attain better performance than the optimal PA-NOMA technique and the conventional orthogonal multiple-access (OMA) technique.

A novel dualband high-temperature superconducting (HTS) bandpass filter is proposed with group delay equalization for 5G emergency communication receivers with N41 and N79 bands in this paper. The dual-folded stub-loaded stepped impedance resonator (DSLSIR) is applied to realize dualband performance. The proposed DSLSIR has miniaturized circuit size and more design freedom to independently adjust the two designed center frequencies, comparing with other reported DSLSIRs. Two cross-coupling transmission lines are added at the top and bottom parts of the cascaded sixth-order filter with DSLSIRs to flatten the group delay of the passband at both bands. A dualband bandpass HTS filter etched on the YBCO superconducting material is fabricated to verify the proposed design method. The measurement is actualized at the temperature of 77 K to make YBCO microstrip lines perform superconducting features. The results show that the first center frequency is 2.595 GHz with 6.2% bandwidth for N41 band and 0.3 dB insertion loss while the second center frequency is 4.85 GHz with 2% bandwidth for N79 band and 0.4 dB insertion loss. Meanwhile, the group delays at the N41 and N79 bands keep 2 ns fluctuations in the 60% passband. The agreement between the measured and simulated results indicates that the proposed dualband bandpass HTS filter with low insertion loss, sharp roll-off skirt and flat group delay is a promising candidate for emergency communication receiver.

A low‐loss bandpass filter with a nonresonant node (NRN) based air‐filled substrate integrated waveguide (SIW) is proposed in this study. It is based on a second‐order inductive diaphragm‐coupled filter with an additional NRN to introduce a transmission zero (TZ) in the upper stopband. Measured results show that the filter has a center frequency of 32.27 GHz with the bandwidth of 0.9 GHz. The insertion loss in the passband is 1.2 dB, and the return loss is better than 24 dB. Due to the presence of TZ in the upper sideband, the AFSIW filter has a sharper transition performance and achieves good selectivity.

A sixteenth-mode substrate integrated waveguide (SIW) bandpass filter with slot line array is proposed in this paper. As the slow wave performance of the slot line array, the circuit size of the proposed bandpass filter is further reduced about 23% comparing with the traditional sixteen-mode one. The simulated and measured results illustrate that the operating frequency is from 1.92 GHz to 2.10 GHz with 9% bandwidth. The return loss at the central frequency is lower than 20 dB while the minimal insertion loss is 0.55 dB.

A novel substrate integrated plasmonic waveguide (SIPW) filter with T-shaped slot line spoof surface plasmon polaritons (SSPPs) is proposed in this paper. By etching the SSPPs array between the two rows of the metal vias of the substrate integrated waveguide (SIW) structure, the SIPW bandpass filter can independently adjust the low cutoff frequency by changing the SIW geometric parameters and the high cutoff frequency by changing the SSPP geometric parameters, respectively. Comparing with the traditional SIPW filter with signal layer or double layers linear slot line SSPPs, the proposed SIPW filter with T-shaped SSPPs has smaller circuit size thanks to the better electromagnetic field confinement ability of the T-shaped SSPPs. The dispersion properties of the SIW unit and the T-shaped SSPPs are discussed and the parameters effect on filter's performance are numerically investigated. A bandpass SIPW filter with T-shaped SSPPs is designed and fabricated with the proposed design method. The measurement results show that its passband is at 5.6-7.3 GHz with the return loss higher than 10 dB and the maximal insertion loss 1.8 dB. Also, its out-of-band spurious rejection is higher than 40 dB at the bandwidth 8.1-14.8 GHz. The agreements between the simulated results and measured results demonstrate the effectiveness of the proposed SIPW filter with T-shaped SSPPs.

A K-band bandstop filter based on the spoof surface plasmon polaritons (SPP) and the capacitively loaded split-ring resonator (RSS) is proposed in this paper. The capacitively loaded RSS consists of two parts: the traditional rectangle RSS and a T-type stub placed at the center of the arm microstrip line of the rectangle RSS. Thanks to the capacitively loaded RSS, the operating frequency of the resonator is reduced, which is helpful for miniaturizing the circuit size. The dispersion feature of the capacitively loaded RSS is studied by simulation and the geometrical parameters effects on the filter’s final performance are discussed. A K-band bandstop filter with spoof SPP and capacitively loaded RSS is designed, fabricated and measured to verify the proposed design methodology. The measured results show that the bandstop filter works at 21.05 GHz-22.95 GHz with more than 40 dB insertion loss.

Partitioning large arrays into subarrays can reduce system cost. In this paper, we use identical subarrays to partition a large rectangular aperture. The periodical structure in a large array is broken down by changing the orientations of the subarrays. In each subarray, the element positions are optimized by particle swarm optimization (PSO) to obtain low sidelobe levels. In order to reduce the coupling among the elements, the minimum element distance measured in Euclidean space is restricted in the procedure of optimization. And a modified PSO is proposed to solve the optimization problem with this constraint. Better results can be obtained than the element distance constraint measured in Chebyshev space. This simple but efficient subarray design method is demonstrated through several numerical simulations.

A dualband rejection filter and a triband rejection filter are proposed in this letter, both of which are implemented by cascading spoof surface plasmon polaritons (SSPPs) of the same structure but with diverse rejection bands. Compared with traditional ones, the proposed filters provide more compact structures, wider rejection bands, and better independent tunability. In the proposed filters, the rejection bandwidth, the center frequency of the rejection band and the filter's cutoff frequency can be adjusted independently. And the different rejection bands in the same filter also can be independently controlled. Agreements between the dispersion of SSPP units and the S-21 of filters are also presented. Measurement results demonstrate that both filters load multiple rejection bands on the 27.7 GHz wide low-pass band and all the rejection bands locate in Ku and K bands. The average rejection bandwidth and the average rejection depth of the two filters are 1.49 GHz and 42.1 dB, respectively.

A effective method to enhance the holding voltage of LVTSCR for electrostatic discharge (ESD) protection applications has been proposed and verified in a 55 nm epitaxial CMOS process. The proposed method improves the holding voltage by removing the STI in NW and adjusting the NMOS gate length. In addition, it can provide an good robustness for ESD protection. Measured results show that the holding voltage can be improved 66% approximately.