IEEE Transactions on Microwave Theory and Techniques最新文献

{"title":"An Extremely Long-Time Stable PML Inspired by Riemann Solver for Electromagnetic Problems","authors":"Zhenzuo Si;Guo Li;Haoqiang Feng;Hongsheng Chen;Qiwei Zhan","doi":"10.1109/TMTT.2026.3728613","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3728613","url":null,"abstract":"As a partial differential equation (PDE)-based time-domain algorithm, the discontinuous Galerkin time-domain (DGTD) method has to deal with a perfectly matched layer (PML) to mimic the infinitely large boundary condition. However, time-domain PML is notorious for its late-time instability, which often appears in an accidental and abrupt manner. This can be attributed to two underlying aspects: first, unlike in the physical region, the mathematical property of the governing equation is not guaranteed in the PML; second, the late-time instability indicates a treacherous manner in the numerical discretization system, since it often appears in a case-dependent way. To resolve these two issues in a consecutive procedure: 1) a Riemann-inspired PML formulation is derived that preserves the exact Riemann solver—the core of DGTD—and recasts the PML effects into a local source term; and 2) based on this structure, a locally implicit deferred correction (DeC) strategy is introduced into the computational electromagnetics (CEM) community for the first time, with only the PML-induced source terms treated implicitly. As a result, our DGTD solver becomes amenable to a variety of extremely long-time stable simulations for complex structures, including a point-source radiation case verified with analytical solution, a 10 000-period resonant cavity case where the benchmark commercial software fails at 700 periods, another two cases—almond and camera box with deep-cavity—verified with experimental radar cross section (RCS) measurement, and finally a large-scale aircraft case with over 100 billion unknowns.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"8723-8740"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wide Temperature Range Stable OEO Enabled by Infinite Tuning Range Microwave Phase Shifter With an Allan Deviation of 6 × 10−15 at 10 s","authors":"Ziye Wang;Peng Zhang;Ping Zeng;Chun Yang;Weijie Xu;Weiqian Zhao;Yuan Wang","doi":"10.1109/TMTT.2026.3727203","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3727203","url":null,"abstract":"This article presents a highly stable injection-locked digital-phase-locked-loop optoelectronic oscillator (IL-DPLL OEO) employing an infinite-tuning-range microwave phase shifter for phase stabilization. The proposed phase shifter compensates delay variations inside the resonance loop, enabling stable operation over a wide temperature range without any thermal control. An FPGA-based digital feedback loop integrating phase detection and control is implemented to stabilize the oscillation phase. Experimental results demonstrate that, after locking to an external reference (REF), the generated microwave signal at 10 GHz achieves an Allan deviation of <inline-formula> <tex-math>$4.1 times 10^{-14}$ </tex-math></inline-formula> at 1 s and <inline-formula> <tex-math>$6.06 times 10^{-15}$ </tex-math></inline-formula> at 10 s. Stable operation is verified over a <inline-formula> <tex-math>$20~^{circ }$ </tex-math></inline-formula>C temperature variation without loss of lock. The results confirm the effectiveness of the proposed stabilization scheme for high-stability optoelectronic oscillators (OEOs) operating under wide temperature variations.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"9123-9132"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of Near-Field Self-Injection-Locked Radar for Wrist-Pulse Sensing: Small-Signal Analysis and Validation","authors":"Haotian Shi;Yuhan Fan;Bo Wang;Yongxin Guo","doi":"10.1109/TMTT.2026.3724860","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3724860","url":null,"abstract":"Near-field wrist-pulse sensing using self-injection-locked (SIL) radar enables accurate detection of small physiological motion and is, therefore, attractive for vital-sign detection. However, existing near-field SIL wrist sensors are still designed largely empirically. Antenna optimization often relies on qualitative field inspection or conventional port metrics, and system-level analyses commonly stop at confirming that dielectric perturbations induce frequency/phase modulation. As a result, a practical and measurement-oriented link from antenna near-field characteristics to the final demodulated baseband output level remains insufficient for design guidance and sensitivity budgeting. This work develops a design-oriented small-signal framework for near-field SIL wrist-pulse sensing. The framework combines the antenna-side perturbation term, injection-locked oscillator response, slope-detection conversion, detector conversion, and baseband gain into a calibrated sensitivity-decomposition chain. In addition, a target-region-oriented near-field electric-field figure of merit (NEFOM), combining effective field coverage and phase coherence, is introduced as a design-stage tool for comparing sensing antennas in near-field wrist-sensing scenarios. The proposed framework is evaluated using a benchmark antenna set and further validated on a fixed SIL radar platform using two 5.8-GHz complementary split-ring resonator (CSRR) sensing antennas with similar matching conditions but different near-field metric levels. The measured results are consistent with the derived small-signal framework.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"9133-9146"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 71-to-76 GHz Eight-Element Isolated LO Frequency Distribution Phased-Array Transceiver With Digital RF Direct-Modulation Transmitter and Reflectionless Sliding-IF Receiver","authors":"Wen Chen;Bingzheng Yang;Changxuan Han;Jie Zhou;Hongxin Tang;Xun Luo","doi":"10.1109/TMTT.2026.3726242","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3726242","url":null,"abstract":"In this article, a 71–76 GHz eight-element isolated LO frequency distribution phased-array transceiver (TRX) using the direct-modulation transmitter (TX) and reflectionless sliding-IF receiver (RX) is proposed. Due to the different modulation and demodulation principles adopted in the TX and RX paths, respectively, the LO generates different frequencies for TX and RX to achieve the proposed TX/RX isolation without extra isolation elements or switching operations. Besides, for the TX path, the <inline-formula> <tex-math>$2 times 8$ </tex-math></inline-formula>-bit quadrature direct-modulator is used to generate the high-data-rate modulation signals. Meanwhile, for the RX path, to suppress the intermodulation (IM) and high-order mixing products, the signal absorption network (SAN) is adopted in a reflectionless RX architecture to reject the out-of-band (OOB) signal reflected back to the mixer. The proposed eight-element phased-array TRX is implemented in a conventional 40-nm CMOS technology. The fabricated phased-array TRX features 16.7–17.3 dBm TX output power and 6.3–6.7 dB RX noise figure within 71–76 GHz. Meanwhile, it shows typical 45.9 dBc isolation for TX and 52.1 dBc rejection for RX. The proposed eight-element TRX array steers a ±30° beam range and supports modulation signals for 4.8 Gb/s 16-QAM and 3 Gb/s 64-QAM.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"8888-8902"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 21-dB-Gain Cascaded Two-Stage Fully Integrated Distributed Amplifier With 1.2 THz Gain-Bandwidth Product and >15-dBm Peak PSAT in 70-nm GaAs pHEMT","authors":"Xu Jiang;Chih-Ju Wu;Jung-Tao Chung;Cheng-Kuo Lin;Austin Ying-Kuang Chen;Chung-Tse Michael Wu","doi":"10.1109/TMTT.2026.3730700","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3730700","url":null,"abstract":"This article presents a cascaded two-stage fully integrated distributed amplifier (DA) implemented in a 70-nm GaAs pHEMT process (PP07) with a peak <inline-formula> <tex-math>${f} {_{text {T}}}$ </tex-math></inline-formula>/<inline-formula> <tex-math>${f} {_{max }}$ </tex-math></inline-formula> of 160/360 GHz. The cascaded DA consists of two identical unit DAs (DA1), each comprising seven sections of cascode gain cells with series peaking and an integrated broadband RF choke (RFC), thereby eliminating the need for an external bias tee. In addition, an AC-coupled two-stage cascaded architecture is employed to enhance both gain and gain-bandwidth product (GBW) while improving the large-signal performance (<italic>OP</i><inline-formula> <tex-math>${}_{text {1dB}}$ </tex-math></inline-formula> and OIP3) of the output stage through bias reconfiguration. The two-stage DA (DA2) achieves a measured broadband gain (<inline-formula> <tex-math>${S} {_{{21}}}$ </tex-math></inline-formula>) of 21 dB over 3.5–108 GHz, resulting in a GBW of >1.17 THz with noise figure (NF) <9> <tex-math>$tau $ </tex-math></inline-formula>) is 49 ps with a corresponding group delay variation (<inline-formula> <tex-math>$Delta tau $ </tex-math></inline-formula>) of ±28.2 ps. At 40/75 GHz, the DA delivers a <inline-formula> <tex-math>${P} {_{text {SAT}}}$ </tex-math></inline-formula> of 15.3/13.2 dBm and an OIP3 of 17.9/14 dBm with a two-tone spacing of 400 MHz. The overall chip area including pads is 1.69 mm². To the best of the authors’ knowledge, this work achieves the highest reported GBW among GaAs pHEMT DAs while maintaining competitive linearity, NF, and figure of merit (FoM) compared with other silicon-based and III–V counterparts reported to date.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"8951-8961"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 170-GHz Radial Power Combining Doubler Based on Circularly Polarized TE11 and TE21 Modes","authors":"Yiming Zhang;Yong Zhang;Huali Zhu;Haomiao Wei;Fei Xiao;Bo Yan","doi":"10.1109/TMTT.2026.3730057","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3730057","url":null,"abstract":"A radial power combining frequency doubler architecture based on circularly polarized TE₁₁ and TE₂₁ modes is presented in this article. In the proposed architecture, the input divider operates with the circularly polarized TE₁₁ mode and generates <inline-formula> <tex-math>$N$ </tex-math></inline-formula> fundamental signals with a progressive phase shift of <inline-formula> <tex-math>$2pi $ </tex-math></inline-formula>/<inline-formula> <tex-math>$N$ </tex-math></inline-formula>. After frequency doubling, the phase progression of the generated second-harmonic signals is doubled to <inline-formula> <tex-math>$4pi $ </tex-math></inline-formula>/<inline-formula> <tex-math>$N$ </tex-math></inline-formula>, which matches the phase condition required by a circularly polarized TE₂₁-mode radial combiner. Therefore, the desired second-harmonic signals can be coherently combined by the TE₂₁-mode radial combiner. Furthermore, the operating principle of the circularly polarized TE₂₁-mode septum polarizer is analyzed, and the minimum number of combining paths required for the proposed architecture is derived from the modal excitation condition. It is shown that at least five paths are required to uniquely excite the desired single-handed circularly polarized TE₂₁ mode. To verify the proposed topology, a 170-GHz five-way radial power combining frequency doubler was designed, fabricated, and measured. The measured results show an output power of 100–203 mW over 163–178 GHz. An average power combining efficiency (PCE) of 69% is achieved at an input power of 750 mW.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"8820-8831"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphology-Guided Dual-Hypermutation Immune Algorithm for Multichip PDN Decoupling in Space-Constrained High-Density SiP","authors":"Bo Wen;Kaijie Xu;Aifeng Ren;Yinghui Quan;Guoyao Xiao","doi":"10.1109/TMTT.2026.3731590","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3731590","url":null,"abstract":"To address the coupled challenges of wideband impedance control, ultralow power-noise tolerance, and strict spatial limitations in power distribution networks (PDNs) for high-density system-in-package (SiP) designs, this study develops a morphology-guided dual-hypermutation immune algorithm (DHIA). The developed method incorporates a physics-aware violation-mapping mechanism based on impedance morphology, together with morphology-guided directed hypermutation, probability-modulated stochastic hypermutation, and concentration-controlled competitive selection. This hybrid evolutionary framework tackles two critical issues that often hinder conventional optimization approaches under multidimensional constraints and high-dimensional decision spaces: the low overall value of feasible solutions and the poor optimization efficiency caused by severe constraint coupling. Compared with five representative baseline methods, DHIA achieves the lowest final fitness under weak-reward weighting while retaining the minimum capacitor count and reducing the occupied area of high-value layout real estate by approximately 9.9% to 14.1%. Under strong-reward weighting, DHIA further reduces the occupancy of this region by approximately 9 percentage points while avoiding excessive reward-driven component accumulation. Ablation, repeatability, and parameter sensitivity analyses further demonstrate the effectiveness and stability of the proposed evolutionary mechanisms. Finally, the calculated impedance results are validated through electromagnetic comparison in the SiP scenario and further verified against simulation and measurement using a scaled PCB prototype, supporting the engineering applicability of the proposed framework.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"8659-8679"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct Synthesis of Miniature Broadband Filters Using Hybrid BAW-Assisted Bridge-T Topologies for 5G Applications","authors":"Santi Cano;Eloi Guerrero;Alfred Giménez;Lluis Acosta;Carlos Caballero;Yazid Yusuf;Jordi Verdú;Pedro de Paco","doi":"10.1109/TMTT.2026.3726143","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3726143","url":null,"abstract":"The ladder network is widely considered to be the most effective topology for acoustic wave (AW) filters in wireless communication. It is composed of either surface AW (SAW) or bulk AW (BAW) resonators, which allow for device miniaturization, low insertion loss, and high selectivity. However, with the introduction of increasingly wider bands in new wireless communication standards, AW ladder filters face topological limitations, as they require an electromechanical coupling factor (<inline-formula> <tex-math>$k_{t}^{2}$ </tex-math></inline-formula>) of approximately twice their fractional bandwidth (FBW). Although the <inline-formula> <tex-math>$k_{t}^{2}$ </tex-math></inline-formula> can be increased beyond 15% using material systems such as scandium-doped aluminum nitride (ScAlN) or LNOI/LTOI, this typically comes at the cost of reduced quality factor. In contrast, bridge-T (BT) topologies decouple the relationship between the <inline-formula> <tex-math>$k_{t}^{2}$ </tex-math></inline-formula> and the FBW through the introduction of balanced parallel-connected branches, enabling solutions that require significantly lower <inline-formula> <tex-math>$k_{t}^{2}$ </tex-math></inline-formula>. This work presents the complete design methodology for four BT topologies that demonstrate excellent performance in broadband applications, including a lowpass filter (LPF), a highpass filter (HPF), an LPF–HPF cascade, and two bandpass filters (BPFs). Since wideband filters cannot be synthesized using narrowband techniques, a direct bandpass (DB) approach based on the coupling matrix (CM) is employed to achieve full control over the entire design procedure. For validation purposes, the four BAW-assisted filters are fabricated using Sc-doped AlN solidly mounted BAW resonators, achieving extremely wideband responses with FBWs of 33% and insertion loss below 1.5 dB across the entire passband. The total device area, including the die mounted on the laminate, is <inline-formula> <tex-math>$3times 2$ </tex-math></inline-formula> mm².","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"9071-9088"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11672893","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Reconfigurable Bandpass Microwave Photonic Filter With Ultrahigh Spectral Selectivity Based on Cascaded High-Q Silicon Microdisk Resonators","authors":"Yuwen Xu;Kunlong Li;Xuan Wu;Haoshi Hao;Bin Wang;Weifeng Zhang","doi":"10.1109/TMTT.2026.3730865","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3730865","url":null,"abstract":"As a cornerstone of radio frequency (RF) signal processing, microwave photonic filters (MPFs) with flexible reconfigurability and high spectral selectivity play a pivotal role in high-resolution radar and 6G wireless communication networks, where precise spectral grooming is of paramount importance. In this work, we propose a reconfigurable bandpass MPF with ultrahigh selectivity based on cascaded high-<inline-formula> <tex-math>$Q$ </tex-math></inline-formula> silicon microdisk resonators (MDRs). The MDR unit leverages an add-drop configuration integrated with a slab waveguide surrounding both the disk and bus waveguides. This design is strategically engineered to enhance optical confinement and minimize propagation loss, thereby enabling a high <inline-formula> <tex-math>$Q$ </tex-math></inline-formula>-factor. Metallic microheaters are patterned atop the MDRs to facilitate thermo-optic tuning of the resonance wavelength. Through precise optical-to-electrical mapping, the high-<inline-formula> <tex-math>$Q$ </tex-math></inline-formula> spectral characteristics of the MDRs are faithfully replicated in the RF domain, enabling microwave filtering with exceptional selectivity. For experimental validation, a cascaded high-<inline-formula> <tex-math>$Q$ </tex-math></inline-formula> silicon MDR chip is designed and fabricated. With the use of the fabricated chip, a high-performance bandpass MPF is implemented, exhibiting a narrow 3-dB bandwidth (BW) of 172.9 MHz, a wide frequency tuning range spanning 2.77–20.52 GHz, a high rejection ratio (RR) of 60.2 dB, and a sharp roll-off rate (ROR) of 75.5 dB/GHz. Moreover, the proposed MPF facilitates flexible BW tunability, manifesting as flat-top passband responses with adjustable 3-dB BWs ranging from 210.3 to 540.7 MHz, consistently sustaining high RRs exceeding 49.3 dB. Featuring a compelling combination of narrow passband, ultrahigh RR, wide frequency tuning range, sharp ROR, and flexible BW reconfigurability, the proposed bandpass MPF paves the way for high-fidelity spectral manipulation in modern RF signal processing systems.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"9157-9169"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Unsupervised Neural Network Equalizer for Real-Time Photonics-Assisted Millimeter-Wave ISAC Systems With Error Propagation Suppression","authors":"Jie Zhang;Wen Zhou;Qihang Wang;Sheng Hu;Sicong Xu;Chengzhen Bian;Jingtao Ge;Jingwen Lin;Siqi Wang;Zhihang Ou;Tengsheng Zhang;Tong Wang;Xin Lu;Xiaoyang Zeng;Jianjun Yu","doi":"10.1109/TMTT.2026.3724412","DOIUrl":"https://doi.org/10.1109/TMTT.2026.3724412","url":null,"abstract":"Integrated sensing and communication (ISAC) has emerged as a key paradigm for future wireless systems, where orthogonal frequency-division multiplexing (OFDM)/discrete multitone (DMT) is widely adopted in communication-oriented architectures. In the bidirectional (BiDi) ISAC system, the communication link is affected by nonlinear distortion and frequency-selective fading, while the sensing link adopts the two-way time-of-flight (TW-ToF) technique, whose ranging accuracy highly depends on stable signal reception and timestamp extraction. To enhance performance with minimal architectural modification, the compensation and equalization techniques at the receiver side have attracted considerable attention owing to their strong generality and ease of deployment. However, conventional decision-directed (DD)-least mean squares (LMS) equalizers are prone to error propagation, conventional blind equalization schemes often suffer from convergence and stability limitations, and supervised neural network-based equalizers usually introduce high computational complexity and implementation overhead. To address these issues, this article proposes a low-complexity blind deep neural network (DNN) equalization method applicable to both the communication and sensing links. The proposed equalizer is developed based on the DD criterion and incorporates a novel piecewise linear activation function, thereby enabling stable blind equalization. Compared with the conventional DD-LMS, the proposed method effectively suppresses error propagation. Furthermore, a real-time (RT) photonics-assisted millimeter-wave BiDi ISAC system based on field-programmable gate array (FPGA) is implemented and experimentally validated. Over a 236-m free-space transmission link, a DMT-16QAM communication data rate of 12.07 Gb/s is experimentally achieved, with a calculated theoretical range resolution of 0.508 cm. By cascading the proposed blind neural network equalizer with the conventional digital signal processing (DSP) chain, the bit error rate (BER) of the communication link can be reduced by up to 0.012, and the BER of the DMT-quadrature phaseshift keying (QPSK) signal in the sensing link remains error-free. This work explores high-performance RT ISAC receiver technologies and provides a valuable reference for the collaborative design of future high-capacity and low-latency ISAC systems.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 10","pages":"9170-9183"},"PeriodicalIF":5.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149222535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}