Microwave and Optical Technology Letters最新文献

{"title":"High-Efficiency Broadband Rectifier Based on Dual Transmission Line","authors":"Sheng Wang,&nbsp;Wenbo Liu,&nbsp;Tao Wang,&nbsp;Jishen Li,&nbsp;Jiazhen Li","doi":"10.1002/mop.70794","DOIUrl":"https://doi.org/10.1002/mop.70794","url":null,"abstract":"<div>\u0000 \u0000 <p>In this paper, an efficient broadband rectifier based on dual transmission line (DTL) structure is proposed. The DTL compensates for the diode's imaginary part while effectively suppressing its impedance variation, and only one transmission line is used in the front end to achieve efficient impedance matching in the broadband. Measured results demonstrate that the rectifier achieves a power conversion efficiency over 60% from 1.5 to 2.5 GHz, peaking at 75.6% at 8 dBm. Furthermore, the design maintains efficiency above 40% from 0.03 to 2.6 GHz at 8 dBm, corresponding to a fractional bandwidth of 195.4%. The overall size is merely 21.5 × 16.6 mm². The results show that the design achieves miniaturization of the circuit while maintaining high efficiency.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149147020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultra-High Isolation Decoupling and Matching Network for mmWave Antennas in Near-Range FMCW Radars","authors":"Zhi Yue Xu,&nbsp;Xinyi Tang,&nbsp;Zhi Ning Chen","doi":"10.1002/mop.70795","DOIUrl":"https://doi.org/10.1002/mop.70795","url":null,"abstract":"<p>A decoupling and matching network (DMN) based on substrate integrated coaxial line technique is proposed to suppress the mutual coupling between a pair of transmitting and receiving antennas operating at 35 GHz. The distorted radiation patterns, typically observed in closely spaced antennas, were improved by introducing carefully designed coupled transformers between antenna feedlines and DMN. The resultant two antennas in the transmitter and receiver produced overlapped patterns to meet radar detection requirements. In this work, a pair of 35 GHz patch antennas with an edge-to-edge gap of mere 0.2 mm was prototyped. The measured 30 dB isolation bandwidth reaches 160 MHz, allowing detection of a target with a weak radar cross section of −14 dBsm at a range of 2 m. The achieved pattern beam shifts by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mn>1</mn>\u0000 \u0000 <msup>\u0000 <mn>8</mn>\u0000 \u0000 <mo>∘</mo>\u0000 </msup>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $1{8}^{circ }$</annotation>\u0000 </semantics></math> from the boresight, with a beamwidth overlap of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mn>8</mn>\u0000 \u0000 <msup>\u0000 <mn>7</mn>\u0000 \u0000 <mo>∘</mo>\u0000 </msup>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $8{7}^{circ }$</annotation>\u0000 </semantics></math>.</p>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mop.70795","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149147003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytically Co-Designed Absorption-Diffusion Coding Metasurface for RCS Reduction","authors":"Thomas Uguen,&nbsp;Raphaël Gillard,&nbsp;Renaud Loison,&nbsp;Jeanne Pagés-Mounic,&nbsp;Gildas Kubické,&nbsp;Philippe Pouliguen","doi":"10.1002/mop.70798","DOIUrl":"https://doi.org/10.1002/mop.70798","url":null,"abstract":"<p>This work proposes a novel and simple design method for an absorption-diffusion metasurface, combining a coding diffusion-type metasurface with an absorbing layer. The diffusion and absorption properties are obtained through an analytical co-design methodology derived from a straightforward Smith chart-based construction. The metasurface itself is entirely metallic and employs a broadband unit cell. Simulations demonstrate a 10 dB bistatic RCS reduction over a 39.1% relative bandwidth for a prototype operating at 22 GHz in the presence of an absorbing layer. The proposed approach provides a new design methodology that explicitly couples the design of an absorbing layer with a diffuse metasurface. Furthermore, this co-design technique can be applied to any existing diffusion metasurface.</p>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mop.70798","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarization-Insensitive Multivariate Hybrid Metasurfaces for Wideband RCS Reduction","authors":"Munna Aziz,&nbsp;Akhila Gouda,&nbsp;Patinavalasa Megh Sainadh,&nbsp;Saptarshi Ghosh","doi":"10.1002/mop.70793","DOIUrl":"https://doi.org/10.1002/mop.70793","url":null,"abstract":"<div>\u0000 \u0000 <p>In this article, polarization-insensitive hybrid metasurfaces are presented for broadband radar cross section (RCS) reduction using a multi-parameter optimization technique. The unit cell consists of a 45°-rotated square-loop metallic patch printed on a dielectric substrate backed by a ground plane. Three geometrical variants of the unit cell are designed by varying the pattern dimensions and substrate height, such that the reflection phase differences among the elements produce wideband destructive interference leading to RCS reduction. Two metasurface arrangements are investigated: one using a checkerboard configuration and the other using a Genetic algorithm (GA)-optimized layout, which result in 10 dB RCS reduction bandwidths of 5.5–11.8 GHz (72.83% fractional bandwidth) and 5.8–13.2 GHz (77.89%), respectively. The novelty of the proposed work lies in the comprehensive numerical analysis and hybrid fabrication technique that integrates FR4 and 3-D printed PLA substrates with tailored heights, enabling multivariate phase control for wideband low-RCS response. Both metasurfaces exhibit polarization-insensitive performance and maintain stable RCS reduction up to 30° oblique incidence. The fabricated geometries are validated through experimental measurements, showing strong agreement with full-wave simulations.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual-Band Non-Contacting Surface-Wave Launcher for WLAN/Wi-Fi 802.11 Signal Excitation Over Single-Conductor Transmission Line","authors":"Ashish Chittora","doi":"10.1002/mop.70792","DOIUrl":"https://doi.org/10.1002/mop.70792","url":null,"abstract":"<div>\u0000 \u0000 <p>A novel design of dual-band surface-wave (SW) launcher for excitation and reception of the WLAN/Wi-Fi 802.11 signal over single-conductor transmission line (SCL), is presented in this paper. The dual-band operation, at lower (2.4 GHz) and upper (5 GHz) frequency bands, is observed in S-parameter simulation results. The SW-launcher is fabricated and validated through measurements in an anechoic chamber as well as in a cluttered environment. The measured S₁₁-parameter is below −10 dB in both Wi-Fi bands. The measured S₂₁-parameter peak is at −9.4 and −20.9 dB in the lower and upper bands, respectively, for 1 m launcher separation. The simulated S-parameters are in good agreement with the measured results in the lower band. However, a shift is observed in the upper band, due to the fabrication inaccuracies, which can be minimized by employing advanced fabrication methods. The launcher performance is evaluated in data communication experiments with the ADALM Pluto SDR device and MATLAB. A color image of 197 MB size is encoded, OFDM modulated, and transmitted using the SW-launcher over the SCL and received at another end. Experiments are performed in LOS and NLOS conditions, varying the frequency band and launcher distance. Minimum average error vector magnitude (EVM) is measured to be −30.18 and −22.10 dB in lower and upper bands, respectively. The launcher has a promising application in short and long-distance power line communication using existing infrastructure.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Design of Ultra-Wideband 2-Bit Switchable Circuit for Programmable Reflectarray","authors":"Yi Xing Li,&nbsp;Yong Han Liu,&nbsp;Shi Yu Wang,&nbsp;Xian Kun Zeng,&nbsp;Yun Bo Li","doi":"10.1002/mop.70785","DOIUrl":"https://doi.org/10.1002/mop.70785","url":null,"abstract":"<div>\u0000 \u0000 <p>A novel method for achieving the ultra-wideband 2-bit phase control by switchable circuit for programmable reflectarray is proposed. The microstrip line based active circuit is composed of three PIN diodes for dynamically selected four different reflective loads of open, short, capacitive and inductive characteristics respectively, and the theoretical calculation about the reflective phase of proposed circuit model can verify the basic method is correct. For considering the design of the ultra-wideband reflectarray, the tightly coupling dipole (TCD) element is introduced for the ultra-wideband electromagnetic wave receiving or radiating. And the co-simulation of the period unit cell, launched by TCD structure and the measurement data from fabricated switchable circuit has shown the good results of 2-bit phase control from 1.8 to 4.2 GHz with the relative bandwidth of 2.33:1.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149028992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Filtenna With Enhanced Gain and High Sideband Suppression in Sub-6 GHz Band","authors":"Maneesha Dwivedi,&nbsp;Neelam Srivastava","doi":"10.1002/mop.70789","DOIUrl":"https://doi.org/10.1002/mop.70789","url":null,"abstract":"<div>\u0000 \u0000 <p>A high-gain filtenna with excellent sideband suppression (SBS) characteristics is presented in this work. The proposed design integrates a bandpass filter, based on a stepped impedance stub resonator, into a pentagon-shaped patch antenna operating at 3.7 GHz (3.56–3.85 GHz). By etching a pair of hexagonal rings and a square-shaped slot in the ground plane, the surface current distribution changes. This generates radiation nulls in the lower and upper frequency bands. As a result, impedance matching and overall filtenna performance improve. The fabricated prototype demonstrates a wide impedance bandwidth for |S₁₁| ≤ −10 dB, a peak gain of 8.2 dBi, and sideband suppression levels exceeding 18.1 dB and 23.2 dB in the lower and upper bands, respectively. With a compact size of 0.495<i>λ</i> × 0.33<i>λ</i> × 0.0176<i>λ</i> at lowest frequency of operation, the proposed filtenna offers a promising solution for 5G and base station applications in the sub-6 GHz frequency band.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149028969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of RF PA Using Reconfigurable Spoof Surface Plasmon Polaritons","authors":"Maojia Geng,&nbsp;Hongbo Zhang,&nbsp;Jialin Cai","doi":"10.1002/mop.70782","DOIUrl":"https://doi.org/10.1002/mop.70782","url":null,"abstract":"<div>\u0000 \u0000 <p>A reconfigurable spoof surface plasmon (SSPP) structure is employed in the design of a radio frequency (RF) reconfigurable power amplifier (PA) in this work. Analyses of fundamental SSPP units are conducted systematically. This design makes use of SSPP structures for both input and output matching networks. A PIN-switch-based reconfigurable SSPP stub is used in the output matching network for reconfigurability. Gradient algorithms are used in the ADS tool to further optimize the performance of the PA. The measurements indicate that the SSPP-based reconfigurable PA achieves an output power (Pout) of 40.3 dBm at 2.42 GHz with 60.6% power-added efficiency (PAE), and 40.5 dBm at 3.44 GHz with 59.7% PAE, with a compact layout area of 124.6 × 54.5 mm. As compared with recently reported works, the proposed PA maintains competitive output power and efficiency while achieving size reduction.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 9","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149047986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A VCO Using a Gain-Enhancement Circuit With a Small-VCO-Gain Variation","authors":"Jian-Yu Hsieh,&nbsp;Guan-Zhi Chen,&nbsp;Ling-Lan Hung,&nbsp;Cheng-Chieh Wu","doi":"10.1002/mop.70781","DOIUrl":"https://doi.org/10.1002/mop.70781","url":null,"abstract":"<div>\u0000 \u0000 <p>A 1-V VCO with a wide-frequency-tuning-range (TR_F) varactor and a gain enhancement circuit by using TSMC 0.18-μm CMOS process has been proposed. The proposed varactor can extend the TR_F and the linear tuning range of the control voltage with a small-VCO-gain (<i>K</i>_VCO) variation. The proposed varactor consists of a small fixed capacitance of 0.18 pF and a large tunable capacitance of 0.98 pF while the control voltage ranges from 0 to 0.6 V. Although the tunable capacitance can be enlarged for extending the TR_F and the PN will be degraded. The proposed varactor can achieve a wide frequency tuning with a single control voltage without extra switched capacitor arrays, transformers, inductors and complex circuits. The TF_F and PN are tradeoff. Hence, a gain enhancement circuit is proposed. The proposed gain enhancement circuit reuses the second harmonic signal for enlarging the fundamental oscillation signal power. The bulks are also used for the signal amplification with the gates in the staked transistor. The oscillation frequency ranges from 1.89 to 2.318 GHz under power consumption (<i>P</i>_D) of 3 mW. The measured TR_F is 20.3%. The measured PN at 1 MHz offset frequency from the carrier signal is −119.7 dBc/Hz with 1/<i>f</i>³ corner frequency of 101 kHz at 2.318 GHz. The measured <i>K</i>_VCO variation is ±7.6%. The wideband figure of merit (FOM_T) at 1 MHz offset frequency from the carrier signal is −188 dBc/Hz.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 9","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liquid-Crystal RIS-Assisted Visible Light Communication for Physical Layer Security: Electro-Optic Channel Modeling and RSMA-Based Secrecy Optimization","authors":"Siyu Li,&nbsp;Can Zhang,&nbsp;Zhijie Zhang,&nbsp;Renxian Li","doi":"10.1002/mop.70778","DOIUrl":"https://doi.org/10.1002/mop.70778","url":null,"abstract":"<div>\u0000 \u0000 <p>This paper proposes an optical simultaneously transmitting and reflecting reconfigurable intelligent surface (OSTAR-RIS) combining a mirror-array reflective panel with a voltage-controlled liquid-crystal (LC) refractive panel, whose electro-optic behavior is modeled via Fresnel interface reflectivity and the molecular-tilt-dependent LC refractive index for physical layer security in partitioned visible light communication (VLC) spaces. Building on this channel model, a dual-room scenario is designed in which Bob receives LoS and mirror-reflected signals in Room 1, while a potential eavesdropper in Room 2 may access only a severely attenuated NLoS component through the electro-optically controlled LC-RIS link. To our knowledge, this is among the first works to exploit OSTAR-RIS's heterogeneous reflection–refraction structure for cross-room VLC physical layer security, and one of the first to jointly optimize RIS orientation, LC refractive index, and RSMA power allocation within a single sum secrecy rate maximization formulation. For the restricted single-eavesdropper case considered here, the resulting structural channel asymmetry between legitimate and eavesdropping links provides the physical basis for positive secrecy without active jamming. A Dual-Sampling Proximal Policy Optimization (DS-PPO) algorithm is employed to solve the resulting non-convex joint optimization over RIS geometry, LC refractive index, and RSMA power allocation. Simulation results show DS-PPO achieves a 250.8 Mbps mean sum secrecy rate—92.7% of the finite-iteration Simulated Annealing (SA) reference—while cutting computation time by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mn>46</mn>\u0000 \u0000 <mo>×</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $46times $</annotation>\u0000 </semantics></math> (8 min vs. 6.18 h), demonstrating superior efficiency for real-time deployment. This electro-optic architecture bridges optical RIS beamforming and reconfigurable antenna control for future RF/VLC hybrid indoor networks.</p>\u0000 </div>","PeriodicalId":18562,"journal":{"name":"Microwave and Optical Technology Letters","volume":"68 9","pages":""},"PeriodicalIF":1.1,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}