De-embedding method for a sensing area characterization of planar microstrip sensors without evaluating error networks.

A de-embedding method for determining all scattering (S-) parameters (e.g., characterization) of a sensing area of planar microstrip sensors (two-port network or line) is proposed using measurements of S-parameters with no calibration.

Simple and inexpensive microwave setup for industrial based applications: Quantification of flower honey adulteration as a case study.

A simple and inexpensive microwave measurement setup based on measurements of magnitudes of transmission properties ( ) is proposed for industrial-based microwave aquametry (moisture or water content) applications. An easy-to-apply calibration procedure based on normalization is implemented to eliminate systematic errors in the measurement system. As a case study, we applied this setup for the quantification of water-adulteration in flower honey.

Simulation and optimization of rectenna systems.

In this paper, we present an entirely simulation-based method to predict the performance of a complete rectenna system that includes all its components: the receiving antenna, the matching circuits between the antenna and the rectification circuit, and the load circuit. Whereas previous efforts to predict the performance of a rectenna system subdivided the system into the antenna part (radiation to AC power conversion) and the circuit part (AC power to DC power conversion), and made assumptions about the performance of the non-linear part of the rectenna based on a specified power level and frequency, in this method, the radiation part of the system is incorporated into the simulation by using Thevenin theorem. The method proposed in this work enables the rectenna designer to predict the performance of the complete rectenna system, at the design stage, for variation in the incident field's power density, angle of incidence, and operating frequency.

Microwave bone fracture diagnosis using deep neural network.

This paper studies the feasibility of a deep neural network (DNN) approach for bone fracture diagnosis based on the non-invasive propagation of radio frequency waves. In contrast to previous "semi-automated" techniques, where X-ray images were used as the network input, in this work, we use S-parameters profiles for DNN training to avoid labeling and data collection problems. Our designed network can simultaneously classify different complex fracture types (normal, transverse, oblique, and comminuted) and estimate the length of the cracks.

Mammography using low-frequency electromagnetic fields with deep learning.

In this paper, a novel technique for detecting female breast anomalous tissues is presented and validated through numerical simulations. The technique, to a high degree, resembles X-ray mammography; however, instead of using X-rays for obtaining images of the breast, low-frequency electromagnetic fields are leveraged. To capture breast impressions, a metasurface, which can be thought of as analogous to X-rays film, has been employed.

AI-Assisted Ultra-High-Sensitivity/Resolution Active-Coupled CSRR-Based Sensor with Embedded Selectivity.

This research explores the application of an artificial intelligence (AI)-assisted approach to enhance the selectivity of microwave sensors used for liquid mixture sensing. We utilized a planar microwave sensor comprising two coupled rectangular complementary split-ring resonators operating at 2.45 GHz to establish a highly sensitive capacitive region.

Techniques to Improve the Performance of Planar Microwave Sensors: A Review and Recent Developments.

Planar microwave sensors have become increasing developed in recent decades, especially in material characterization (solid/liquid) as they provide regions highly sensitive to the surrounding medium. However, when it comes to deciphering the content of practical biological analytes or chemical components inside a host medium, even higher sensitivities are required due to their minute concentrations. This review article presents a comprehensive outlook on various methodologies to enhance sensitivity (e.

Ternary optimization for designing metasurfaces.

A fully automated approach for designing metasurfaces whose unit cell may include metallic vias is proposed. Towards this aim, a ternary version of the particle swarm optimization (PSO) algorithm is employed in order to find the optimal metallic pattern and via-hole positions simultaneously. In the proposed design method, the upper surface of the unit cell is first pixelated.

Real-time multi-functional near-infrared wave manipulation with a 3-bit liquid crystal based coding metasurface.

We propose a new generation of reprogrammable multi-functional bias encoded metasurfaces for dynamic wave manipulation using liquid crystals (LC). This metadevice is an array of unit-cells based on LCs to provide the desired phase steps based on its large birefringence property. The presented 3-bit coding metasurface (CM) use 8 states of "000"-"111" to control and manipulate the scattered wave at λ=1.

Intelligent Sensing Using Multiple Sensors for Material Characterization.

This paper presents a concept of an intelligent sensing technique based on modulating the frequency responses of microwave near-field sensors to characterize material parameters. The concept is based on the assumption that the physical parameters being extracted such as fluid concentration are constant over the range of frequency of the sensor. The modulation of the frequency response is based on the interactions between the material under test and multiple sensors.

A Pixelated Microwave Near-Field Sensor for Precise Characterization of Dielectric Materials.

A highly sensitive microwave near-field sensor based on electrically-small planar resonators is proposed for highly accurate characterization of dielectric materials. The proposed sensor was developed in a robust complete-cycle topology optimization procedure wherein first the sensing area was pixelated. By maximizing the sensitivity as our goal, a binary particle swarm optimization algorithm was applied to determine whether each pixel is metalized or not.

Wide-band Beam-scanning by Surface Wave Confinement on Leaky Wave Holograms.

A two-dimensional (2-D) metasurface design for backward leaky wave suppression in microwave regime is proposed based on the theory of holography. The so-called Rabbit's ears phenomenon describes that the backward mode in the reference wave plays the destructive role and makes the holography principle to behave properly mainly in an only narrow frequency interval. Here, we explore the utilization of the surface wave reflectors to suppress the backward mode to achieve wide-band holograms.

Unconditionally stable FDTD algorithm for 3-D electromagnetic simulation of nonlinear media.

For the first time, an unconditionally stable finite-difference time-domain (FDTD) method for 3-D simulation of dispersive nonlinear media is presented. By applying a new adopted alternating-direction implicit (ADI) time-splitting scheme and the auxiliary differential equation (ADE) technique, the time-step in the FDTD simulations can be increased much beyond the Courant-Friedrichs-Lewy (CFL) stability limit. Thus, in comparison to the classical nonlinear FDTD method, the computational time for the proposed approach is decreased significantly while maintaining a reasonable level of accuracy.

Pixelated Metasurface for Dual-Band and Multi-Polarization Electromagnetic Energy Harvesting.

A dual-band and polarization-independent electromagnetic energy harvester composed of an array of pixelated unit cells is proposed. The pixelated unit cell is basically a dual-band resonator loaded with two resistors which model the input impedance of a power combining circuit in a complete harvesting system. To design the unit cell, a topology optimization approach based on pixelization of the surface of the unit cell and application of a binary optimization algorithm is used.

Pixelated Checkerboard Metasurface for Ultra-Wideband Radar Cross Section Reduction.

In this paper we designed and fabricated a metasurface working as a radar cross section (RCS) reducer over an ultra wide band of frequency from 3.8 to 10.7 GHz.

Assessment of RF radiation levels in the vicinity of 60 GSM mobile phone base stations in Iran.

Increasing development of mobile communication infrastructure while enhancing availability of the technology raises concerns among the public, who see more cell towers erected each day, about possible health effects of electromagnetic radiations. Thereon, a survey of radio-frequency radiation from 60 GSM base stations was carried out in Tehran, Iran at several places mostly located in major medical and educational centres. Measurements were performed at 15 locations near each base station site, i.