International Journal of RF and Microwave Computer-Aided Engineering最新文献

A wideband high-temperature superconducting (HTS) duplexer is designed and is characteristic of more than 50% fraction bandwidth in its two channels. The duplexer is composed of a linear half-wavelength resonator and two channels. Each channel is composed of five dual-mode resonators with the attenuated second harmonic. To improve the isolation of the duplexer, we loaded a quarter-wavelength resonator at the output port of Channel 2; besides, a 5-pole dual-hairpin lowpass filter is cascaded at the output port of Channel 1 to improve its out-of-band rejection. The duplexer was fabricated on a MgO substrate coated with YBCO thin film on its double sides, and the area of the duplexer is 44.42 × 8.00 mm. The measured results showed that the 1 dB bandwidth of the channels is 2.679–4.645 and 5.083–9.014 GHz, respectively; the corresponding fractional bandwidths are 55.7% and 58.1%. The rectangularity of 60/3 dB is 1.51 and 1.11, respectively. The isolation between two channels is larger than 70 dB. The out-of-band rejection in the frequency range lower than 15 GHz is larger than 36 dB. The return loss is 10.6 and 6.0 dB and will be improved by subsequent tuning.

In this letter, a highly efficient and wideband power amplifier (PA) is proposed based on resistive–resistive series of continuous modes (Res-Res SCMS) with a new microstrip low-pass filter (LPF). By employing a conventional real-to-real impedance transformer, the output and input matching networks are realized by incorporating the transistor′s parasitic elements. A new compact microstrip LPF, which exhibits a wide stopband with high suppression and a sharp frequency response, also serves as a real-to-real impedance matching. It shows less than 0.1 dB insertion loss and greater than 20 dB attenuation in the 4.2–10 GHz frequency range. The proposed PA is designed and fabricated using a CGH40010F GaN high electron mobility transistor (HEMT). The measured result shows that over the frequency band of 0.5–2.9 GHz, the large-signal gain is bigger than 9.77 dB, the drain efficiency (DE) is 58.2%–76.5%, and the output power is 39.77–42.99 dBm when the input power is 30 dBm.

This paper presents an innovative coupling design for a bandpass substrate integrated waveguide (SIW) filter, enabling high selectivity and facilitating flexible design. The proposed filter design has two parts: one is a mixed coupling structure, and the second part is a cross-coupling path. Both parts contribute to transmission zero (TZ) near the passband. Cross-coupling creates TZ, while mixed-coupling offers TZ and filter design flexibility. The cross-coupled path is analyzed in three configurations: without a load, with an inductive load, and with a capacitive load. To demonstrate this, three filter designs are simulated and fabricated based on the type of path load. The filter achieves center frequencies near 27 GHz with a fractional bandwidth exceeding 3%. Four to five TZs are introduced to enhance selectivity. Key performance metrics include a return loss exceeding 15 dB within the passband and an insertion loss between 1.65 and 2.1 dB. The measured results align with the simulated results, validating the structure and theory of the cross-coupled load.

RETRACTION: Y. Luo, Y. Gu, H. Zhang, J. Xu, F. Qian, G. Yang and H. Cui, “A wideband mmWave microstrip antenna based on zero-mode and TM-mode resonances,” International Journal of RF and Microwave Computer-Aided Engineering, vol. 32, no. 8 (2022): e.23219, https://doi.org/10.1002/mmce.23219.

The above article, published online on 3^rd May 2022 in Wiley Online Library (http://wileyonlinelibrary.com), has been retracted by agreement between by the journal Editorial Board and John Wiley & Sons Ltd. The retraction has been agreed due to significant overlap with a previous publication by the authors [1].

The overlap occurred due to the paper being under consideration at the two journals simultaneously. The authors requested to withdraw this paper prior to publication on April 27^th, 2022; however, this was not processed, and authors subsequently signed the electronic license agreement on May 1^st, 2022, resulting in publication.

The authors agree to the retraction of the article but do not agree to the wording of the notice.

Orbital angular momentum (OAM) antennas have recently attracted attention for their potential to enhance communication capacity and and robustness against interference. However, most existing designs rely on complex multilayer feed structures. This work presents a compact, single-layer, series-fed dual-mode OAM antenna composed of four patches arranged in a circular array with a 29 mm radius. The series-feeding network can be excited from two ports to simultaneously generate the l = +1 and l = –1 modes. Measurements were performed in an anechoic chamber to obtain far-field realized gain patterns and holographic phase distributions in the 6 GHz band. Two identical antennas were also tested in a transmit–receive configuration in a multipath environment using a two-port vector network analyzer. The maximum realized gains are 3.65 dBi for l = +1 and 4.8 dBi for l = –1 at 6.1 GHz. The proposed single-layer topology enables dual-mode OAM generation and supports multimode multiplexing, enhancing spectral efficiency and suppressing interference without added hardware complexity.

This paper proposes a 4 × 4 beamforming network (BFN) using a novel configuration. The proposed architecture utilizes a two-layer multi-aperture and multislot coupler (MA/MSC). Power coupling between ports within each layer is achieved through designed apertures. Additionally, power distribution between the upper and lower layers is facilitated by the embedded slots between the two layers. To validate the performance of the proposed design, a four-beam antenna is fabricated by connecting a 4 × 2 SIW slot antenna to the BFN. The satisfactory performance of the proposed BFN is validated through antenna measurements. Compared with conventional designs, the proposed BFN offers several advantages: fewer components, elimination of crossovers, and compact size (approximately 20 mm × 38 mm). These features make it highly suitable for fifth-generation (5G) wireless communication applications due to its size and simplicity.

Multiple-input multiple-output (MIMO) technology has garnered widespread attention due to its remarkable ability to significantly augment system channel capacity. With the objective of boosting the channel capacity for the fifth-generation (5G) mobile communication, we propose a 5G terminal MIMO antenna with a compact structure and high isolation operating in 3.4–3.6 GHz. In order to achieve greater channel capacity while ensuring maximum isolation among MIMO elements, 14 miniaturized units utilizing self-decoupling technology are positioned under the chassis model. This results in a significant decrease in mutual coupling, reaching a level of −13.5 dB, while simultaneously increasing the channel capacity to a level of 55.5–59 bps/Hz. Additionally, the feasibility of the proposed mobile terminal MIMO antenna is demonstrated through simulations involving human hand models, thereby confirming its practical application.

The design and analysis of nanoelectromechanical systems (NEMSs) provide significant challenges due to the dominance of surface forces, quantum-scale effects, and complex material properties, where classical electrostatics and continuum mechanics become inadequate. Numerical modeling has therefore emerged as a powerful approach to predict device behavior prior to fabrication by ensuring reliability and stability. In this paper, a novel 3-bit distributed NEMS transmission line (DNTL) phase shifter is proposed and modeled using the quasilinear reproducing kernel particle method (QL-RKPM). Unlike conventional finite element or finite difference methods, the QL-RKPM provides enhanced accuracy and convergence in capturing the electromechanical behavior of nanoscale membranes by incorporating singular moment matrices and emphasizing linear approximations suitable for large deformations. The proposed DNTL phase shifter is designed with 33 periodically loaded NEMS membranes integrated over a coplanar waveguide (CPW) transmission line, enabling discrete phase control at three states (45°, 90°, and 180°). Each membrane is modeled with 101 particles within its structural boundary to accurately extract the up (C_u) and down (C_d) capacitance values using QL-RKPM. The extracted capacitances, 7.06 fF and 20 pF, respectively, are incorporated into a capacitor–inductor–resistor (CLR) equivalent circuit model and simulated in the Advanced Design System (ADS) to evaluate the RF performance. The phase shifter achieves a low phase error of ±2° with an average insertion loss of −0.6 dB and a return loss of −26 dB at 22 GHz by demonstrating excellent signal integrity and efficiency. The novelty of this work lies in the integration of QL-RKPM-based nanoscale electromechanical modeling with RF circuit–level performance evaluation, which allows precise prediction of capacitance variations and phase states without resorting to expensive or iterative fabrication. Furthermore, the proposed design provides multibit discrete phase shifting capability with compact size, low insertion loss, and improved reliability, making it a promising candidate for high-frequency phased arrays used in 5G wireless systems.

A novel frequency selective surface (FSS) element consisting of multilayer Jerusalem cross and double ring is proposed in this paper, which could independently achieve transmission/reflection polarization conversion at higher/lower frequency bands. Based on this fascinating characteristic, a dual-band transmissive–reflective circular polarizer is designed, fabricated, and measured by employing a set of these FSS unit cells. The designed circular polarizer consists of 19 × 19 elements and is capable of flexibly transforming linearly polarized (LP) incident wave into circularly polarized (CP) transmitted/reflected counterpart at higher/lower frequencies. Both simulated and measured results are basically consistent, which prove our proposed circular polarizer has the advantages of planar integration, easy manufacture, and dual-band operation. The fabricated polarizer prototype shows 3-dB axial ratio bandwidths of 10.7% (11.5–12.8 GHz) and 11.7% (8.8–9.9 GHz) for the transmitted and reflected wave at normal incidence, respectively. The proposed approach provides a new way to develop multifunctional devices for generating transmissive and reflective CP signals at different bands, which is promising for applications in modern satellite communication systems.

This paper presents a highly efficient and high-gain single-port dual-band antenna designed for WLAN applications. The antenna offers −10 dB impedance bandwidths of 450 MHz (2.3–2.75 GHz) and 2300 MHz (3.95–6.25 GHz), covering the WLAN 2.4 and 5 GHz bands. It consists of a radiating patch and an artificial magnetic conductor (AMC) reflector with overall dimensions of 50 × 80 × 28.2 mm. Both the radiating element and the AMC unit are attached to an FR-4 substrate with a relative dielectric constant ε_r of 4.4 and loss tangent tanδ of 0.02. By incorporating the reflector, the antenna achieves directional radiation and high gain. The proposed antenna prototype was tested, demonstrating total efficiencies exceeding 83% in both frequency bands. Additionally, at the operating frequency of 2.4 GHz, the simulated and measured half-power beamwidths are approximately 100° and 86°, respectively. At the frequency point of 5.5 GHz, the simulated and measured half-power beamwidths are approximately 56° and 50°, respectively.