Ke Wu

Montreal Polytechnic · Department of Electrical Engineering

This letter presents a dual-band substrate integrated waveguide (SIW) filter based on the dual modes of TE $_{101}$ and TE $_{102}$ in multilayer structures. Its middle metal layers feature mixed-coupling structures, where the slots implement independent magnetic coupling for the TE $_{101}$ and TE $_{102}$ bands, and the holes implement additi...

In this article, a novel design for ultrawideband transition is presented to connect double ridge waveguide and stripline technology. The introduced structure contains a Teflon seal that holds an inner conductor connecting the double ridge with the middle strip of the stripline configuration. This pin is shaped to ensure the mechanical stability of...

Integrating microwave (MW) and terahertz (THz) operations and technologies is a promising solution in support of future multifunction and multistandard wireless systems such as joint sensing and communication platforms. However, the coexistence of MW and THz in a single receiver is a challenge to accommodate such a dual-band scheme of large frequen...

In this work, a monoblock hardware receiver solution for dual-polarization multichannel wireless systems is proposed and demonstrated for the first time. The receiver benefits from the use of a square waveguide scheme enabling dual-polarization features. Two orthogonalized polarizations, namely, horizontally and vertically polarized waves, can simu...

Beyond 5G and 6G technologies mark a pivotal evolution in the telecommunications landscape. They are not only anticipated to deliver unprecedented speed and capacity but also to serve as critical enablers for a host of emerging technologies and applications, including joint communications and sensing, autonomous driving, augmented reality (AR), vir...

In this work, we enable an 8-way radial combiner with a coaxial interface that revolutionizes high-power handling. Our innovative approach eliminates the need for small gaps near the feeder line, significantly boosting power capabilities, as confirmed through Spark3D software, capable of exceeding 450 KW. Exceptional performance is observed with am...

Conventional horns inevitably suffer from the phase error issue and associated design constraint of contour (e.g., the optimum criteria are typically employed) because of the embedded plane-to-cylindrical (or spherical) wavefront conversion process. These design dilemmas can be well addressed by using the leaky-wave enabled horn (i.e., the leaky ho...

Ultra-fast and energy-efficient connections are the keys to future wireless communication technologies. However, even in full duplex communication systems, the accessible spectrum is portioned because up-links and down-links are set to occupy non-overlapping frequency channels. Here we report an unprecedented in-band full-duplex transceiver archite...

The wirelessly driven Internet of Things (IoT) is expected to revolutionize sensor applications by replacing conventional wired systems with ad hoc wireless sensor networks. IoT-based sensor networks allow the addition and expansion of new sensor nodes without the additional costs and hassles related to the use of new wires, including expensive and...

A deep integration of active-integrated antennas (AIAs) with high transmitter efficiency, high polarization purity and low interference has presented a difficult-to-ignore challenge for designers. This fundamental problem in AIA design emerges from the lack of an impedance-matching flexibility between antenna aperture and active element for high dc...

We propose and investigate a methodology based on convolved electric and magnetic currents for the generation of multi-band responses over a space-shared radiating surface. First, a single wideband antenna operation principle based on interleaved dipole and slot modes is studied and analyzed using full-wave simulations followed by a qualitative tim...

This article presents a highly efficient method for substrate-integrated-waveguide (SIW) filters to achieve very wide stopbands. By employing the proposed trisection slots in addition to the bisection slots as the inter-coupling structures, all spurious modes below TE505 of a SIW filter working in the fundamental mode TE 101 (fo) can be eliminated...

Antenna and array technologies have been in constant evolution for more than 100 years for various purposes in wireless connectivity among distant devices and/or systems by radiating electromagnetic waves, usually operating in a far-field manner. With the proliferation of the Internet of Things (IoT) that started more than two decades ago, wireless...

Integrability and modularity of multiple functions present key features for future AI-driven wireless systems. In this letter, a cooperatively operating architecture of two highly integrated building blocks is proposed and studied as a multifunction receiving array system. One module is a hybrid array for two joint operations, namely simultaneously...

Mutual-coupling effects are of utmost importance in the development of high-frequency circuits and systems. However, it is a common practice to ignore those couplings when establishing equivalent circuit models. Neglecting these couplings leads to inaccurate circuit modelling. Therefore, it becomes imperative to account for mutual couplings in the...

In this article, a quadrature harmonic self-oscillating mixer (QHSOM) is proposed, studied, and demonstrated for future large array multifunction receivers. Its implementation is based on single-stage direct-conversion harmonic receiver topology. The proposed receiver unit is composed of a pair of harmonic self-oscillating mixers (HSOMs), which are...

Temperature variation poses a significant challenge for battery-free sensors and Internet of Things (IoT) systems, mainly due to the absence of built-in temperature compensation modules. This work presents a strategy to identify Schottky diodes for low-power RF-to-dc Dickson charge pump (DCP) rectifiers to enhance temperature stability. Theoretical...

This article proposes an approach of designing a wide-power-range RF power harvester integrated with a dc – dc boost converter, in order to facilitate wireless charging driven by wireless power transfer (WPT). The approach addresses the operational constraints posed by a dc – dc boost converter with maximum power control functionality, achieving hi...

This article presents a class of high-density waveguide dual-polarized receivers operating at terahertz (THz) frequencies, fully integrated on a single complimentary metal–oxide–semiconductor (CMOS) die. Unlike conventional TEM-mode dual-polarized receivers, which require doubled chip size for polarization diversity, our proposed nonTEM-mode substr...

Leakage electromagnetic energy widely exists in the vicinity of high-voltage power lines. This work proposes a comprehensive electric field energy harvester, which can drive a commercial consumer-oriented Zigbee-based Wireless Sensor Platform (WSP). Electric field energy harvesting is selected as its energy density is about 60 uJ/m3 under 525-kV po...

With the development of multistandard, multiband wireless/microwave circuits and systems, a wide stopband could be essential for a substrate integrated waveguide (SIW) filter to eliminate interference. However, the performance of the current wide-stopband SIW filters is not good enough, particularly the stopband extension. Here, based on a multilay...

Unlike popular multiband antenna array radiation based on either electric or magnetic surface currents, the use of mutually interleaved and tightly coupled electric and magnetic currents results in an aperture-reuse space-efficient multiband radiating surface for highly integrated antenna-frontend architecture and spatial power combining design sce...

Semiconductor monolithic mode-locked lasers (MLLs) are potential solutions for generating high-speed optical pulses in future mobile fronthaul networks in the millimeter-wave (mmW) bands. Our previous studies have investigated using buried heterostructure (BH) quantum dash (QDash) multi-wavelength lasers for photonic mmW applications. Here we prese...

This article presents and derives an analytical model for accurately analyzing lossy dielectric waveguides in the THz regime. By considering the dielectric loss of waveguides and applying the impedance boundary condition (IBC), the proposed method can accurately simulate the waveguiding behavior. By applying the Fourier series expansion along with...

A compact double periodic leaky-wave antenna is designed in this paper, which has been developed to suppress the open-stopband (OSB). This antenna is loaded with shorting vias and folded slots on a substrate integrated waveguide (SIW) periodically. The proposed antenna can scan from backward to forward continuously with a high radiation gain at bro...

In this paper, a rectenna with quasi-full spatial coverage is developed for RF power harvesting applications in 5G context. The rectenna is designed based on a compact dielectric resonator antenna (DRA) that is composed of two laterally radiating elements with opposite half-space radiation. To demonstrate the rectenna’s performance, the proposed DR...

In this paper, an ANN model development technique is described for efficient and fast high frequency structure design and optimization. Unlike the well-documented space mapping and aggressive space mapping technology, we map equivalent circuit model parameters to field model geometric parameters through a neural modeling. First, a complete EM struc...

Electromagnetics (EM)-based optimization techniques have always been a major interest in the microwave research community due to their vital role in the design and development of microwave circuits and systems. Achieving the desired specifications in terms of S-parameters over different frequency bands is one of the critical steps in the microwave...

In millimeter-wave (mmW) and terahertz (THz) applications, the transmission behavior along circuit structures and components, such as radiation and leakage losses, is critical for their overall performances. It is imperative to develop low-loss interconnect and transmission techniques that should be used for the construction of building circuit blo...

This article investigates flexibly using mixed coupling in substrate integrated waveguide (SIW) filters to efficiently improve selectivity. To this end, a mixed coupling structure is proposed, which can be used as a universal coupling module to efficiently produce transmission zeros (TZs) in an inline/conventional SIW filter without degrading the s...

In this work, four low-loss compact waveguide phase shifters with self-compensating characteristics are proposed, studied, and demonstrated over the entire G-band (140-220 GHz) for the first time. The full-band phase shifting is achieved by combining opposite properties of the reference line and the main line. In addition, the proposed phase shifte...

In this work, a theoretical and experimental investigation of substrate-integrated non-radiative dielectric (SINRD) waveguide is conducted in terahertz (THz) band. Parametric effects on operation bandwidth and transmission performance are studied. An alumina-based SINRD waveguide with a thickness of 0.254 mm is first demonstrated in WR3-band. The p...

In the development of a multifunctional and multi-standard analog frontend module in emerging and future wireless systems, multifunction antenna array is an indispensable component. To this end, the aperture-shared technique has come of age, and demonstrated significant advantages in the cost-effective design of efficient, compact, multiband, multi...

Mixed coupling has been used in substrate integrated waveguide (SIW) filters to eliminate the transmission of spurious modes. However, the elimination only applied to the first spurious mode. Here, we propose a new mixed coupling structure that consists of slots for magnetic coupling and holes for electric coupling. Using it as the inter-coupling s...

Radiation produced by a slow-wave along a generalized non-uniform structure is investigated. It shows that the radiation pattern of a non-uniform and non-periodic traveling-wave series-fed array can be explained by the slow-wave dominant mode, and the slow-wave radiation pattern of a periodic leaky-wave antenna can be explained by both the slow-wav...

A short-open-thru (SOT) numerical de-embedding technique is proposed and studied in this work. In particular, a generalized methodology for circuit model development is derived for the extraction of accurate circuit parameters over a wide range of frequency. The entire de-embedding process is described, and the circuit model development strategy is...

This article presents a novel class of compact and wide stopband bandpass filters based on dual-mode folded circular substrate integrated waveguide cavities (FCSIWCs). By employing both TM $_{020}$ and TM $_{110}$ modes of the FCSIWC as resonant modes and TM $_{010}$ mode as nonresonating mode, a doublet with two poles and two transmission zeros...

Because of the PDF conversion error, the shadow backgrounds in Figs. 13(a) and 17(a) in our previously published review article [1] vanished. The correct figures are shown in this correction.

A simple polarization-insensitive coherent radio-over-fiber (RoF) link with increased spectrum efficiency and transmission capacity is proposed and demonstrated. Instead of using two polarization splitters (PBSs), two 90° hybrids, and four pairs of balanced photodetectors (PDs) in a conventional polarization-diversity coherent receiver (PDCR), a si...

This letter presents a novel class of dual-band filtering baluns using perturbed substrate integrated waveguide (SIW) circular cavities. By stacking the SIW cavities vertically, flexible filtering order can be realized. The stacked structure also permits the introduction of cross-couplings between non-adjacent cavities, which can be used to generat...

Nonradiative dielectric (NRD) waveguides have been studied and exploited to address the leakage issue in dielectric waveguides caused by discontinuities. With the proliferation of substrate integration technologies, planarized substrate-integrated NRD (SINRD) waveguides have emerged, which are found to be more suitable for terahertz (THz) integrate...

Ultrashort pulse transmission has been recognized as a primary problem that fundamentally hinders the development of ultrafast electronics beyond the current nanosecond timescale. This requires a transmission line or waveguide that exhibits an all-pass frequency behavior for the transmitted ultrashort pulse signals. However, this type of waveguidin...

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In this paper, an ANN model development approach is outlined and studied for the development of tunable bandpass filter (tBPF). Circuit models are fast and efficient for design and optimization while physical models based on electromagnetic full-wave fields are accurate but computationally expensive and slow. In this work, an equivalent circuit mod...

Electromagnetic interference (EMI) is considered a dangerous threat that simultaneously affects the sensitivity of electronic devices and the human body owing to the rapidly growing usage of high-frequency electronic and wireless devices. In this study, we demonstrated the EMI shielding properties of lightweight and electrically conducting three-di...

Inspired by the well-known power/energy leakage phenomenon between an unshielded grounded coplanar waveguide (GCPW) and its neighboring parallel-plate waveguide (PPW), a class of simple, low-cost, and planar leaky-wave antennas (LWAs) exhibiting wideband fixed-beam radiation and tailorable directional angle are systematically investigated and devel...

Radio frequency (RF) energy harvesting and wireless power transmission (WPT) technologies —both near-field and far-field—have attracted significant interest for wireless applications and RFID systems. We already utilize near-field WPT products in our life and it is expected that RF EH and far-field WPT systems can drive the future low-power wireles...

Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.

Ultrabroadband systems and ultrafast electronics require the generation, transmission, and processing of high-quality ultrashort pulses ranging from nanoseconds (ns) to picoseconds (ps), which include well-established and emerging applications of time-domain reflectometry, arbitrary waveform generation, sampling oscilloscopes, frequency synthesis,...

In a highly integrated analog radio-over-fiber transceiver, seamless integration of the antenna-frontend is crucial as an antenna is generally implemented on a high-κ material, which is set to highly degrade the antenna's performance. This work is concerned with the radiation behavior improvement of a planar leaky-wave antenna with an inductive par...

Providing energy to Internet of Things (IoT) apparatuses is ever more challenging. Humans are increasingly invested in the revolutionary new scenario that experts call Industry 4.0 , where billions of electronic devices are interconnected with one another. The operations of battery charging or battery replacement for these devices will soon becom...

Reports on news of interest to SPS society members.

High-performance tunable RF/microwave and millimeter-wave filter design is a challenging task due to the lack of a basic theory. The filtering characteristics are highly sensitive to the variation of tuning elements which are commonly modeled and achieved by optimization algorithms. However, those optimizations only provide satisfactory results wit...

Reports on news of interest to MTTS Society members.

Millimeter-wave (mmW) Y-junction ferrite circulators above 40 GHz have limited bandwidth due to the lack of ferrite materials having a high saturation magnetization above 5000 G and the simple and traditional circuit design approaches that cannot produce wideband circulators in this frequency range. To increase the bandwidth of mmW Y-junction ferri...

This work proposes a multiport transmitter frontend (MTFE) architecture to bolster the concurrent dual-band transmission while supporting the digital predistortion (DPD) processing. The proposed architecture consists of two back-toback multiport networks driven by only one local oscillator (LO) through a multilayer power divider. The low-power LO s...

This article presents a technique for dual-band substrate integrated waveguide (SIW) filters to implement independent coupling for their dual bands based on multilayers and overlapped cavities. It is achieved by using the proposed intercoupling slots in the middle layers. The slots parallel to and near the edge implement TE101 coupling, while the o...

This paper proposes and explores high-performance Substrate-Integrated Image Guide (SIIG) techniques for THz applications. Due to its low-loss transmission, planar geometry, and metallic ground plane that can be shared among other circuit components, the SIIG structure is an ideal candidate for THz integrated circuits and systems development. By co...

In this paper, a self-contained dual-input receiver architecture based on the interferometric technique is proposed and demonstrated for the first time for paralleled-multichannel wireless systems. Different from conventional counterparts, the proposed receiver consists of dual-input RF channel paths, and only one sole hardware is used to realize f...

Multiport interferometric receivers are recognized for their competitive low-power and low-cost wireless sensor solutions. However, the systematically generated rectified wave components in a conventional direct-conversion interferometric receiver can saturate the receiver in a radio propagation environment comprising multichannel signals in the op...

A cooperative radar-communication (RadCom) system architecture employing a multi-port interferometer receiver is introduced and demonstrated for low-power and low-cost multifunction wireless applications. The proposed system operates in both radar sensing and radio communication modes, which are arranged in different time slots within a single hard...

This paper presents a comprehensive analysis of pulse compression capability in hybrid and gyromagnetic non-linear transmission lines (NLTLs). The corresponding theoretical analysis in the hybrid NLTLs is derived and discussed in detail with the generation and sharpening aspects of leading and trailing pulse edges. The parameters responsible for pu...

Graphene-based microwave devices have enabled reconfigurability, thus paving the way to the realization of flexible wireless terahertz systems with featured performances. Despite great progress in the development of graphene-based terahertz devices in the literature, high insertion loss and wide tunable range are still significant challenges at suc...

One of the fundamental problems in power amplifier (PA) design is the mismatch between the optimum loads for maximum output power and maximum efficiency. This work demonstrates that a GaN transistor of choice can reduce such mismatch when operating at the minimum input RF power required (Pin) to obtain its maximum output power. Furthermore, this w...

This brief presents a new wide stopband substrate integrated waveguide (SIW) filter with multimode suppression based on a multilayer structure. All spurious modes below TE404 of a multilayer SIW filter operating in TE101 could be effectively suppressed by moving the intercoupling slots away from the sidewall by about 1/6 of the cavity’s width. To v...

The IEEE Microwave Theory and Technology Society (MTT-S) Inter-Society Committee is one of the standing committees in the MTT-S Administrative Committee (AdCom), whose objectives, functions, and activities were well described in an early write-up by former Chair Dr. Steven C. Reising [1] . This article informs readers about the committee’s curren...

In this letter, we discuss a methodology of converting a modular antenna array, which was originally designed for the 23 GHz unlicensed band, to the emerging 60 GHz 5G band for a short-range millimeter-wave (mm-wave) detection application. The feeding structure is made up of substrate-integrated waveguide (SIW) and coupling brick-slots, allowing re...