IEEE Journal of Microwaves

?? Special Issue on Microwaves in Climate Change ?? In January, JMW published a special issue on “Microwaves in Climate Change”, highlighting how microwave technology contributes to climate research and practical applications. Find the full issue here: https://lnkd.in/gcXcV88N The issue includes 16 papers covering topics such as: ?Ozone monitoring ?Power beaming and energy harvesting ?Bird migration tracking ?Agricultural emissions monitoring These contributions come from both traditional electrical engineering communities and researchers in geosciences and physics. ?? Free print copies will be available—sign up through the JMW web page in early March to request one. If you're working on relevant research and want to contribute to future issues, contact Peter Siegel, JMW Editor-in-Chief ([email protected]).

??Article spotlight: Microwave Imaging for Breast Cancer Detection - A Comparison Between VNA and FMCW Radar This paper compares expensive vector network analyzer techniques to much less costly and more compact FMCW radar instruments for breast cancer screening. The trick is that you have to have very wide absolute bandwidth (BW) to get good range resolution. For the radar, range resolution is proportional to c/(2xBW), but one also has to work at a low enough frequency that the radar signal can penetrate through the tissue. This makes the absolute bandwidth required for high resolution difficult to achieve. The authors employ a synthetic aperture radar technique in the 6–14 GHz frequency band and show that the FMCW radar images correlate almost identically with images reconstructed from a well-calibrated vector network analyzer operating at similar wavelengths on breast tumor phantoms. The FMCW systems are significantly less costly and equally effective at imaging the tested inclusions at sub-one-centimeter scales. This paper is from our March 2025 issue. ?? Read the full article here: https://lnkd.in/gyJaiTY8? ?? Topics covered in this article: Breast cancer, FMCW radar, microwave imaging, radar system, SAR, transceiver ?? Authors: Martin Maier, Sebastian Paul, Milan Rother, Simona Di Meo, Marco Pasian, J?rg Sch?bel, Vadim Issakov

??Article spotlight: Contactless Glucose Sensing Using Miniature mm-Wave Radar and Tiny Machine Learning The paper discusses the use of an FMCW (frequency modulated continuous wave) radar with ten percent bandwidth to detect changes in skin reflectivity as the glucose concentration in vivo varies. Since the FMCW technique allows the separation of signals from different distances (penetrations into the skin), there is a slight dependence of the return signal that correlates with glucose concentration. The authors use machine learning to extract resonant features from the radar cross section measurements and rank them against known glucose concentrations in in-vitro samples. The results look fairly promising with current precision at 10 mg/dl. The authors have now set the stage for characterization of their instrumentation and extraction algorithms for deployment in in-vivo tests. This paper is from our March 2025 issue. ?? Read the full article here: https://lnkd.in/gDG4_Gjf? ?? Topics covered in this article: AI, convolutional neural network (CNN), contactless healthcare, glucose sensing, tiny machine learning (TinyML), mm-wave, radar, wireless sensing ?? Authors: Reza Nikandish, Caroline Sheedy, Jiayu He, Ruth Crowe, Deeksha Rao

??Article spotlight: Fast In-Phantom Absorbed Power Density Evaluation at mmWaves Based on Infrared Measurements In this paper, authors discuss a fast method for determining the absorbed microwave power in exposed skin by measuring the heat signature at the skin surface through an external IR camera and using thermal transport analysis to couple the temperature rise to the specific absorption rate. They demonstrate their technique with a very highly characterized and accurate skin phantom and present correlative results for retrieving the absorbed power density from exposure of their phantom to various RF antenna sources at 60 GHz. This paper is from our March 2025 issue. ?? Read the full article here: https://lnkd.in/ghHj6b-F? ?? Topics covered in this article: Absorbed power density (APD), compliance testing, dosimetry, electromagnetic field (EMF), human exposure, millimeter waves (mmWaves), infrared (IR), near-field measurements, temperature, wireless devices, 5G, 6G ?? Authors: Massinissa ZIANE, Artem Boriskin, Maxim Zhadobov

??Article spotlight: In Vitro Epithelial Lung Cell Vitality Measurements With mm-Waves This paper tackles the very significant problem of characterizing living biological materials (epithelial cells in this article) in the microwave bands. Due to their small volume (<< wavelength), near field techniques are typically deployed in the microwave region to characterize small samples. At millimeter and submillimeter wavelengths, probes are still much larger than a single cell, but smallish groups of cultured cells can be characterized using reflection and transmission techniques. Parameters of interest include index and loss determination in static samples, but also changes that occur during cell growth and/or cell viability. In this paper, the authors develop a novel and generally applicable non-contact microwave S-parameter measurement technique that can be used on cultured cells over a wide range of frequencies up to and beyond 325 GHz. They also model the cells in culture media over time and correlate the reflection coefficient with changes in cell density, hydration, and viability (through to apoptosis). This is a very interesting and detailed applications article and will most certainly stimulate additional work in this growing field of microwave tissue characterization. This paper is from our March 2025 issue. ?? Read the full article here: https://lnkd.in/gE-fJ-J7? ?? Topics covered in this article: Biological cells, biosensors, dielectric waveguide, lithography, microwave sensors, millimeter wave, physiology ?? Authors: Philipp Hinz, Adrian Diepolder, Giorgio Fois, Manfred Frick, Christian Damm

Our March issue is here! Find all twenty open access articles here:?https://lnkd.in/g6-j2mmB?In addition to our technical articles, we also welcome our 20 new JMW Topic Editors, and announce our 2023 Best Paper Award (we intentionally run one year behind on this particular honor) and our list of 2024 Outstanding Reviewers.

??Article spotlight: Optimization-Based Design of Multi-Band Branch-Line Coupler With Arbitrary and Band-Distinct Power Division Ratios and Phase Differences In this paper, the authors describe an optimization procedure for designing branch-line couplers with arbitrary output power division ratios and phase differences that also can differ at arbitrarily designated frequencies. The procedure hones in on the optimum design within a predefined tolerance. The authors demonstrate the technique on tri-band and quad-band microstrip couplers in the 1–5 GHz range. The algorithm is shown to work very effectively and may be applicable to other microwave component optimization problems. This paper is from our January 2025 issue. ?? Read the full article here: https://lnkd.in/gmsUjk8t? ?? Topics covered in this article: Coupler, multi-band, arbitrary power division ratios, arbitrary phase difference, optimization ?? Authors: Abdullah Alazemi, Mohamed Koura

??Article spotlight: A New Class of Wideband Quadrature Coupled-Line Forward Couplers This paper provides details on a new class of directional couplers with arbitrary coupling ratios. The design combines two sections of strongly coupled lines with an uncoupled line. Closed form equations are given and a synthesis technique presented. A prototype with 39% bandwidth and very flat phase and magnitude response at 3 GHz center frequency is presented. This paper is from our January 2025 issue. ?? Read the full article here: https://lnkd.in/g8rgfC-t? ?? Topics covered in this article: Couplers, directional couplers, quadrature couplers ?? Authors: Henning Mextorf, Winfried Schernus

??Article spotlight: A Novel Compact Wideband Bandpass Filter With High Upper Stopband Rejection This paper involves transmission zero filters implemented in 65nm CMOS. The authors achieve a 3-dB bandwidth of 24 GHz centered at 94 GHz and an insertion loss of 4.6 dB. The expanded stop band they achieve goes all the way out to 190 GHz with a rejection above 25 dB. This paper is from our January 2025 issue. ?? Read the full article here: https://lnkd.in/gGUQT9xJ? ?? Topics covered in this article: BPF, coupling capacitor, dual-mode resonator, stub loaded resonator, high upper stopband rejection ?? Authors: Qijun Lu, Jiawei Sun, Hao Zhang, Tao Zhang, zhangming zhu

??Article spotlight: Tunable Bandpass Filters With Co-Integrated Isolator and Switching-Off Functionality This paper reports on an active filter structure that has center frequency tunability, can be switched on or off, and can serve as an isolator as well. The filters are demonstrated in the 1.4–1.9 GHz range. This paper is from our January 2025 issue. ?? Read the full article here: https://lnkd.in/gX2CWyHU? ?? Topics covered in this article: Bandpass filter (BPF), isolator, RF switch, tunable filter, unilateral filter ?? Authors: KEXIN LI, Dimitra Psychogiou