Validating Implants for MRI Safety Assessment

Researchers from the University of Houston and the U.S. Food and Drug Administration present a model validation for evaluating the safety of active implantable medical devices used under magnetic resonance imaging radio frequency emissions. They show that validation pathways suggested by ISO 10974 are both inefficient and incomplete, and suggest improvements.
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Papers for Texas Symposium (Waco, TX, 2-3 April)

The Texas Symposium on Wireless and Microwave Circuits and Systems (Waco, TX, 2-3 April) invites papers (from industry and academia) on 5G and millimeter-wave wireless technologies, wireless biomedical applications, antennas and propagation, spectrum management, test and measurement, wireless power transfer, photonics, the Internet of Things, and allied topics.
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Characterizing Materials via Multiple Offset Reflects

NIST researchers report a new multiple-offset-reflect technique that provides one-port on-wafer materials characterization at up to 110 GHz...without first-tier calibration. Comparative multline thru-reflect-line analyses on fused silica and SU-8 conform with literature permittivity values.
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WAMICON Wireless and Microwave Papers Due 7 Feb.

Papers are due 7 Feb. for the 21st Wireless and Microwave Technology Conference (WAMICON 2020, Clearwater Beach, FL, 15-17 Apr.). The conference addresses multidisciplinary wireless and RF research, with the theme, "Wireless Devices and Systems Making Mad Connections from Space to the 5G IoE."
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Six-Billion-Fold Two-Step THz Amplification

In a new, two-step technique, a pre-amplifier first upconverts THz waves into a near-infrared beam. Noise (a problem with earlier devices) is then removed, and the main amplifier downconverts the signal to terahertz again. This two-stage THz parametric amplifier affords extremely high amplification (up to 6 billion-fold; 98 dB) for an ultra-weak input of 500 zJ (1 zJ = 10^−21J ).
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Reconfigurable Negative Group Delay Circuits

A novel reconfigurable negative group delay (NGD) device consists of two branch-line couplers connected by two varactors of different capacitance. Adjusting capacitances changes circuit gain/loss (over the range -14 to -53 dB) and group delay (from 0 to -90 ns). An active circuit (with two simple amplifiers and fixed capacitances) controls gain/loss over the range 17 to -18 dB and group delay over 0 to -80ns.
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A 135-150-GHz Frequency Tripler in Micromachined SU-8

An international team describes a bias-less frequency tripler based on WR-5 waveguides micromachined from five 432-μm-thick layers of silver-plated SU-8. Tests of the Schottky-diode-based design at 135-150 GHz showed conversion loss of 16-18 dB and input return loss better than 18 dB--demonstrating SU-8's potential for devices requiring submicrometer feature resolution.
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Kinetic Plasma Models for High-Power Microwave Devices

Improvements in electromagnetic particle-in-cell (EM-PIC) algorithms on unstructured grids effectively account for multiscale plasma phenomena as applied to analyses of laboratory plasmas, vacuum electronic devices for generating high-power microwave signals, and RF electronics multipactor effects--with particular attention to multipactor effects and mitigation in coaxial cables.
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Novel Trombone Topology for Wideband True-Time-Delay Implementation

A novel trombone topology for controllable true-time delay provides discrete variable delays with minimum insertion loss variation. A prototype in 0.18-μm CMOS technology (operating over 8-18 GHz) provides a maximum delay of 109.3 ps (in 15.6-ps steps) using a conventional passive second-order all-pass network (APN) and novel passive fourth-order APN delay cells. Average insertion losses were 18.2-22.5 dB.
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Coming Up: Radio & Wireless Week, Wireless and Microwave Tech

Upcoming MTT-S-sponsored meetings include: the Texas Symposium on Wireless and Microwaves Circuits and Systems (WMCS, Waco, TX, 2-3 Apr.), Wireless and Microwave Technology (WAMICON, Sand Key, FL, 15-17 April); Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMiC, Cardiff, UK, 16-17 Apr.); Microwaves for Intelligent Mobility (ICMIM, Linz, Austria, 20-21 Apr.), and more.
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