Transverse Electromagnetic Cell Research Articles

Background levels and brain organoid impact of RF field exposure in a healthcare environment

Introduction: This study is an introduction to the empirical and impact evaluation of radiofrequency electromagnetic field (RF-EMF) radiation exposure in a healthcare environment, focusing on an indoor microenvironment. It explores the expression of various genes associated with cellular responses, cell proliferation, senescence, and apoptotic cell death. The assessment analyzes current personal mobile communications (2G-5G FR1), providing a clear understanding of RF-EMF exposure and compliance with regulatory limits.Methods: The signals from different wireless communication systems at Hospital Universitario de Canarias (HUC) in Tenerife, Canary Islands, Spain, were examined in 11 locations. Four measurement campaigns were performed with frequency-selective exposimeters (PEMs) and an EME Spy 200 MVG, and experimental electric field values were compared as a long-term exposition. The frequency with the highest contribution (2.174 V/m) observed (1840 MHz) in UMTS was selected for biological effects evaluation.Results: The study focuses on four locations with the highest exposure to communication systems (downlinks), analyzing the results to verify compliance with regulations that ensure the safety of patients, the general public, and healthcare workers. LTE B20 (DL), GSM+UMTS 900 (DL), GSM 1800 (DL), UMTS 2100 (DL), and LTE B7 (DL) exhibited relatively higher E/m values throughout the campaigns, and these values consistently remained below the ICNIRP reference levels, signifying a consistently low level of exposure. In addition, this work presents the biological effects on neural stem cells (NSCs) using 3D brain organoids (BOs) exposed to RF signals in a validated and commercial experimental setting: the Gigahertz Transverse Electromagnetic cell (GTEM). The GTEM allows for the creation of homogeneous field electromagnetic fields in a small, enclosed setting and guarantees exposure conditions in a wide range of frequencies. BOs are an in vitro 3D cell-culture technology that reproduces the cellular composition and structure of the developing brain. Analyzing the expression of several genes associated with cellular responses, cell proliferation, senescence, and apoptotic cell death, we found that exposure of BOs at 1840 MHz did not affect mRNA expression in brain genes related to apoptosis or senescence. However, a decrease in gene expression for cell proliferation and cell activity markers was observed during the differentiation stage of BOs.Discussion: The discussion emphasizes the coexistence and evolution of various heterogeneous networks and services throughout the four measurement campaigns. Across all measured results, the levels of the obtained E-field were consistently well below the exposure limits set by internationally accepted standards and guidelines. These obtained values have been established in order to consider their potential effects on cell proliferation and cell activity, especially in differentiating biological organisms. Consequently, the results obtained and the methodology presented could serve as a foundational framework for establishing the basis of RF-EMF assessment in future heterogeneous 5G developments, particularly in the millimeter wave (mmWave) frequency range, where the forecast is for massive high-node density networks.

Routing Technique for Microwave Transmission Lines to Ensure UWB Interference Immunity

This article presents a novel routing technique for designing microwave transmission lines (TLs) that provide improved functionality. Unlike traditional practices, we propose locating two independent traces close to each other, resulting in strong electromagnetic coupling and potential unwanted crosstalk between traces. However, we show that the suggested routing schemes can significantly increase the ultra-wideband interference immunity of electrical circuits by using modal distortions and reflections, as demonstrated in our study of four prototypes of TLs in the form of serpentine and spiral designs with strong and weak coupling between pairs. To better predict and analyze the microwave behavior in such TLs, we used new simulation techniques based on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$</tex-math> </inline-formula> -norms study. Our investigation of these TLs in a transverse electromagnetic cell in the frequency range from 10 MHz to 5.3 GHz showed a low level of radiated emissions. The results indicate that the serpentine scheme with strong coupling between pairs provides the best protection of two independent TLs against ultra-wideband interferences. Moreover, the used electrodynamic approach is in full agreement with the experimental study, further validating the effectiveness of the proposed routing technique.

An Electromagnetic Interference Immune PAM-4 Transceiver System

This article presents the design of a pulse amplitude modulation (PAM-4) transceiver that supports high-speed wireline communication in the presence of electromagnetic interference (EMI). The proposed PAM-4 transceiver uses an input level shifter (ILS) and a modified electrostatic discharge (ESD)-protection circuit to reduce the effects of EMI at the transmitter. In order to overcome the effects of EMI at the receiver, the front end is designed with an enhanced input common-mode range. The transverse electromagnetic (TEM) cell method, as provided in the IEC 62132-2 standard, is followed to experimentally verify the radiated EMI-immunity of the proposed PAM-4 transceiver system over its traditional counterpart. For proof of concept, the proposed EMI-immune PAM-4 transceiver and the traditional PAM-4 transceiver circuits are implemented using the 130-nm BiCMOS process. The proposed transceiver operates at a data rate of 6.5 Gbps while maintaining an eye-opening of 70 mV for each bit in the presence of EMI, meeting the requirement of the IEEE 802.3 bs standard. The proposed PAM-4 transceiver withstands a wide range of EMI frequencies that span from 150 kHz to 2 GHz with an EMI power of 0–20 dBm.

Interferences of Electromagnetic Pulses on Microcontroller Units

In this study, electromagnetic interference testing of microcontroller units (MCUs) under different electromagnetic pulse (EMP) amplitudes, full width at half maximum (FWHM), and at different angles was carried out on an EMP cell. The coupling path of the radiation-type EMP experiment on the circuit board is random. However, in several experiments with two pins specific to a certain integrated circuit, by measuring the interference voltage of MCU pins, the statistical results indicate that as the pressure of the air gap switch of the power source increased, both the breakdown voltage and the electric field in the transverse electromagnetic (TEM) cell increased, resulting in higher electromagnetic interference (EMI) received by these two pins. As the capacitance of the storage capacitor increased, the EMI also increased. In addition, the results showed that the interference of EMP on the MCU had strong directionality; i.e., path selectivity, which was related to the structure of the MCU. X-ray imaging of the destroyed MCU showed that when the internal wiring direction of the pin is consistent with the propagation direction of the interference pulse, the EMI was minimal or even unnoticeable.

Calibrating a Radio Frequency Electrooptic Sensor for Field-Relevant Temperature Conditions in a Laboratory Setting

Legacy high-powered electric field measurement devices, such as flush plate dipoles (D-dots) and waveguides, are the primary diagnostic tools used for free-field experimentation. Unfortunately, these metallic devices perturb the electric field of interest via scattering and require the use of coaxial cables (fluctuate with temperature). Electrooptic (EO) probes offer a potential solution as they minimally perturb the electric field, and fiber-optic cables can be designed to correct or prevent temperature fluctuations. However, to replace the legacy diagnostics, it is critical that the EO probes are calibrated in field-relevant conditions (outdoor temperatures between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.4~^{\circ} \text{C}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$49~^{\circ} \text{C}$ </tex-math></inline-formula> ). Characterization of a modern EO sensor is done by using an environmental chamber and a gigahertz transverse electromagnetic (GTEM) cell. The collected data in this article indicates that modern <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {LiNbO}_{{3}}$ </tex-math></inline-formula> EO sensors have linear changes across both various temperatures and electric fields. This article outlines the process of creating field-relevant conditions in laboratory settings. Because temperature effects are ubiquitous with most devices, the temperature response of the EO probe needed to be isolated from all other temperature effects. Using a novel way of applying the design of experiments (DoE) method, the temperature response of the EO probe can be isolated and a linear trend can be resolved. The data suggest that the EO probe under test can be used to measure RF fields as long as a small correction factor is applied to 0.52% per °C for every °C away from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$22.0~^{\circ} \text{C}$ </tex-math></inline-formula> in either direction.

In-vivo measurement of radio frequency electric fields in mice brain

With the development of novel technologies, radio frequency (RF) energy exposure is expanding at various wavelengths and power levels. These developments necessitate updated approaches of RF measurements in complex environments, particularly in live biological tissue. Accurate dosimetry of the absorbed RF electric fields (E-Fields) by the live tissue is the keystone of environmental health considerations for this type of ever-growing non-ionizing radiation energy. In this study, we introduce a technique for direct in-vivo measurement of electric fields in living tissue. Proof of principle in-vivo electric field measurements were conducted in rodent brains using Bismuth Silicon Oxide (BSO) crystals exposed to varying levels of RF energy. Electric field measurements were calibrated and verified using in-vivo temperature measurements using optical temperature fibers alongside electromagnetic field simulations of a transverse electromagnetic (TEM) cell.

WiFi Related Radiofrequency Electromagnetic Fields Promote Transposable Element Dysregulation and Genomic Instability in Drosophila melanogaster.

Exposure to artificial radio frequency electromagnetic fields (RF-EMFs) has greatly increased in recent years, thus promoting a growing scientific and social interest in deepening the biological impact of EMFs on living organisms. The current legislation governing the exposure to RF-EMFs is based exclusively on their thermal effects, without considering the possible non-thermal adverse health effects from long term exposure to EMFs. In this study we investigated the biological non-thermal effects of low-level indoor exposure to RF-EMFs produced by WiFi wireless technologies, using Drosophila melanogaster as the model system. Flies were exposed to 2.4 GHz radiofrequency in a Transverse Electromagnetic (TEM) cell device to ensure homogenous controlled fields. Signals were continuously monitored during the experiments and regulated at non thermal levels. The results of this study demonstrate that WiFi electromagnetic radiation causes extensive heterochromatin decondensation and thus a general loss of transposable elements epigenetic silencing in both germinal and neural tissues. Moreover, our findings provide evidence that WiFi related radiofrequency electromagnetic fields can induce reactive oxygen species (ROS) accumulation, genomic instability, and behavioural abnormalities. Finally, we demonstrate that WiFi radiation can synergize with RasV12 to drive tumor progression and invasion. All together, these data indicate that radiofrequency radiation emitted from WiFi devices could exert genotoxic effects in Drosophila and set the stage to further explore the biological effects of WiFi electromagnetic radiation on living organisms.

Analysis of Higher-Order Mode Effects in the Resistively Loaded Monocone TEM Cell

This article proposes a method to obtain the analytic solution of electromagnetic field inside the practical finite monocone transverse electromagnetic (TEM) cell. The higher-order modes existing in a practical monocone TEM cell are solved and analyzed for the first time, which explains the field distortion corresponding to the ideal standard field. The proportionality factors of these modes are determined by comparison with simulation results. The calculation results (i.e., sum of modes) are consistent with simulation and experimentally validated. This work can be used for monocone design of eliminating higher-order modes and expanding the time window, and mode analysis for other kinds of TEM cells.

Deep Learning Inverse Analysis of Higher Order Modes in Monocone TEM Cell

This article proposes a broadband inverse analysis method for the higher order modes inside the resistively loaded monocone transverse electromagnetic (TEM) cell. The analytic solutions of the field pattern for each higher order mode are derived in the frequency domain. The deep learning technique is employed to effectively predict coefficients of these modes over a wide frequency range (1.885–300 MHz) only given the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field amplitude distribution. The predicted results agree well with measurement ones, which validates the accuracy of the deep neural network method, and furthermore, it is analyzed in the time domain with fast Fourier transform (FFT). This work reveals the mechanism of higher order mode-induced field distortion in both the frequency domain of broadband and the time domain, provides guidance for elimination of higher order modes in monocone TEM cells, and can be extended to mode analysis for other kinds of wideband antennas.

Near-Field Shielding Analysis of Conformal Coating Materials for Integrated Circuits

This article analyzes a near-field shielding performance of conformal shielding materials for integrated-circuits (ICs) by experiments. Two test boards with loop-type and patch-type patterns are designed to generate magnetic-field and electric-field, respectively. These sources mimic typical electromagnetic radiations from actual ICs. For shielding analysis, single-layered conductive materials, multilayered conductive and magnetic materials, hybrid materials with a mixture of conductive and magnetic pastes are considered as conformal shielding materials, which are coated on the test boards for measurements. Magnetic-field and electric-field shielding effectiveness (SE) of the materials evaluate by measurements using loop-probe, strip-line, and gigahertz transverse electromagnetic cell at the frequency range from 300 kHz to 3 GHz. Near-field SEs measured by three methods correspond generally well with each other at the frequency range up to a few hundred MHz. At the higher frequency, the ambient EM environment can affect the accuracy of the near-field measurements by the loop-probe and strip-line. For validation, numerical simulation is fulfilled and compared with measured results. Theoretical interpretation based on the Schelkunoff's SE decomposition is also addressed.

Recent trends for 5G in vitro exposure systems dosimetry and setup

5G wireless communications networks are being massively studied and developed. This new technology introduces new operating frequencies and employs smart adaptative antennas that allow focusing electromagnetic waves in specific directions. Bioelectromagnetic investigations to assess exposure and interactions with living entities of these new 5G signals are carried out. This contribution aims to present current trends on exposure systems designs for bioelectromagnetic studies with associated computational and experimental dosimetry. The extension to 5G signals of classical exposure systems such as transverse electromagnetic cells (TEM cells) and new innovative designs are discussed.

Fundamental Investigation of Wave Propagation inside IC-Striplines upon Excitation with Hertzian Dipole Moments

To characterize the electromagnetic compatibility (EMC) of integrated circuits (ICs), especially the radiated emissions in the near field, transversal electromagnetic cell (TEM cell) or IC-stripline measurements (IEC 61967) are utilized. Due to the ongoing miniaturization and the increasing operating frequencies, accurate EMC characterization of ICs is becoming more important to achieve first-time-right designs. In order to avoid expensive redesigns, the prediction of these measurements in terms of a simulation workflow would be of high interest. Because of the high computational burden needed to conduct 3D full-wave finite element (FEM) simulations of both the device under test (DUT) and the measurement system, an equivalent representation of the DUT by means of analytical incident fields, such as Hertzian dipole moments, can be considered. In order to develop an order-reduced model of this kind, it is essential to have a solid understanding of the coupling and wave propagation effects inside the measurement systems. In the present paper, a fundamental investigation of the coupling paths between an IC-stripline and electric or magnetic dipole moments is presented and the results are compared to the existing analytical models. The results show that these analytical models, originally developed for TEM cells, are only partially valid for IC-striplines. It has also been shown that even for simple test structures, such as loop and monopole antennas, the representation in terms of one single dipole moment is insufficient.

Dosimetry of Microelectrodes Array Chips for Electrophysiological Studies Under Simultaneous Radio Frequency Exposures

Studying the response of neuronal networks to radio frequency (RF) signals requires the use of a specific device capable of accessing and simultaneously recording neuronal activity during electromagnetic fields (EMF) exposure. In this study, a microelectrode array (MEA) that records the spontaneous activity of neurons is coupled to an open transverse electromagnetic (TEM) cell that propagates EMF. We characterize this system both numerically and experimentally at 1.8 GHz. Two MEA versions were compared, for the first time, to determine the impact of their design dissimilarities on the response to EMF. Macroscopic and microscopic measurements using, respectively, a fiber-optic probe and a temperature-dependent fluorescent dye (Rhodamine-B) were carried out. Results indicate that one MEA shows more stability toward the changes of the surrounding environment compared to the other MEA. Using a fiber-optic thermometer, the measured specific absorption rate (SAR) probe value in the center of the more stable MEA was 5.5 ± 2.3 W/kg. Using a Rhod-B microdosimetry technique, the measured SAR value at the level of the MEA electrodes was 7.0 ± 1.04 W/kg. SAR values are normalized per 1 W incident power. Due to the additional metallic planes and a smaller chip aperture, this new recording chip is steadier in terms of SAR and temperature stability allowing high exposure homogeneity as required during biological experiments. A typical neuronal activity recording under EMF exposure is reported.

On the electromagnetic shielding properties of carbon fiber materials

Introduction. Due to the good electrical and thermal properties of carbon, carbon-based materials represent a major trend is various applications, including electromagnetic compatibility. Among carbon-based materials, graphite-impregnated woven fabrics represent a new trend in the field of electromagnetic shielding, with the perspective of being used for protective clothing. The novelty of the proposed work consists in the exhaustive comparative analysis of various carbon-based sample shields by employing both simulation and experimental methods. The selected configurations included a simple graphite plate, a graphite powder strip network, and a graphite-impregnated fabric with 2´2 twill weave. Purpose. The main scope of the analysis is to prove the efficiency of the graphite-impregnated twill woven fabric in the field of electromagnetic shielding. Methods. Two main research methods were employed: simulation and experiment, both following the same protocol: the shield placed in the middle, with the excitation (transmitting antenna) on one side and the measurement / receiving antenna on the other. The experimental stage was thorough, being performed in two different laboratories and by applying the double transverse electromagnetic (TEM) cell method and the shielded box method. Results. A significant difference yielded from the comparison of the simulation and experimental results for the shielding effectiveness, probably due to the fact that the virtual model is an idealized version of the physical one, not taking into account its imperfections. The virtual analysis yielded the graphite plate shield as the most efficient, followed closely by the twill fabric. The graphite strip network had significantly poorer performance compared to the other two shields, probably due to the electrical contact imperfections between the graphite strips and the optical transparency of the shield. The main focus of the analysis was the twill woven graphite-impregnated fabric; therefore, its shielding effectiveness was determined through simulation and experiment. The experimental analysis was performed in two stages in two different electromagnetic compatibility laboratories, by employing the double TEM cell method and the shielded box method, respectively, both methods providing similar results and classifying the shielding performance as good. Practical value. The paper provides an accurate analysis of the graphite-impregnated 2´2 twill woven fabric in terms of electromagnetic shielding effectiveness, by employing both simulation and experimental methods, and comparing its performance to the one other graphite-based shields.

Orientation Effect of the Electromagnetic Field Coupling for Device in a TEM Cell

In this article, the orientation effect of electromagnetic coupling for a device in a transverse electromagnetic (TEM) cell is explained in the frame of the model with intercoupling of equivalent electric and magnetic dipoles taken into account. Different from the widely used model, which predicts a half-circle period of the orientation effect, the proposed model predicts a full-circle period due to the introduced intercoupling. The intercoupling of the electric and magnetic field interaction inside the TEM cell and the full-circle period orientation effect is demonstrated first by simple straight and meander microstrip lines, which is then compared to a segment of an integrated circuit (IC). For the application of the proposed model to a complex device, a limited number of pairs of intercoupling electric and magnetic field dipoles can be introduced to predict the complicated orientation effect of a running large-scale IC in TEM cell measurement. The extracted dipoles are in good agreement with the near-field scanning results. The widely used Wilson model should be checked carefully in the application of field to line analysis.

An EMI-Immune PAM-4 Transmitter With Input Level Shifter in 130-nm BiCMOS Technology

This work presents a design of an electromagnetic interference (EMI)-immune pulse amplitude modulation-4 (PAM-4) transmitter. The traditional PAM-4 transmitters are prone to failing in the presence of EMI, which is experimentally verified. The proposed PAM-4 shows superior performance over the traditional PAM-4 transmitter, in the presence of EMI, by using an Input Level Shifter (ILS). ILS minimises the effect of EMI on a PAM-4 signal by reducing the input commonmode level of the transmitter and renders it compatible with the previous logic state. The proposed PAM-4 transmitter is fabricated in 130-nm BiCMOS technology with a chip area of 580mum×915 mum. EMI-immunity measurements are aligned with the IEC 62132-2 standard by using a transverse electromagnetic (TEM) cell for radiated EMI-immunity. In the presence of a wide range of EMIs, the proposed PAM-4 transmitter operates at a data rate of 6.5 Gbps and maintains the minimum required eye-opening of 70mV as per the standard IEEE 802.2bs. The proposed EMI-immune transmitter can withstand EMI powers of 0-16dBm in frequencies ranging from 1MHz to 1.5 GHz.

Ultra-Wideband and Wide-Angle Insensitive Absorber Based on TCDA-Under-Tightly Coupled Dipole Array

In this article, an ultra-wideband and wide-angle insensitive absorber is proposed. The unit cell of the proposed structure consists of a tightly coupled dipole array (TCDA2) under another TCDA (TCDA1) that is twice the height of TCDA2 (TCDA-under-TCDA structure). TCDA1 of the unit cell acts as either a lossless (or lossy) antenna when the frequency is out of (or in) the operating frequency range of TCDA2. Reciprocity is applied to design TCDA1 as an absorber when the frequency is out of the operating frequency range of TCDA2 (lossless antenna region). On the other hand, the multisection impedance matching technique is applied for TCDA1 to be an absorber when the frequency is in the operating region of TCDA2 (lossy antenna region and reciprocity cannot be applied). In addition, a metasurface (MS) and vertical metal strip (VMS) are employed to develop the wide-angle insensitivity absorber. A -10 dB reflection bandwidth of 0.63-6.55 (10.4:1) is achieved with a 0.126λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> at the lowest operating frequency under normal incidence. The bandwidth is moderately reduced to 0.69-6.75 (9.78:1) with a 0.138λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> for the TE mode and 0.75-6.22 (8.29:1) with a 0.150λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> for the TM mode under 45° oblique incidence. The measured results of the fabricated absorber using the transverse electromagnetic (TEM) cell are in good agreement with the simulated results.

Near-Field Scanning Based Shielding Effectiveness Analysis of System in Package

The electromagnetic interference (EMI) problems are crucial for system-in-package (SiP) due to the high demand of miniaturization and dense integration. Shielding methods are generally employed to protect SiP from EMI, through assessing the key performance index, i.e., shielding effectiveness (SE). In this article, the SE of a SiP is evaluated by using near-field scanning method. The SEs derived by using maximum near-field values and average near-field values are comparatively analyzed. The difference in near-field patterns of the unshielded and shielded SiPs may incur overestimation of the SE by using maximum field values. Both simulation and measurement results manifest that the gap between SiP and printed circuit board (PCB) will significantly change the radiation pattern of a shielded SiP, and thus has a great impact on the SE, especially when the frequency is above 1 GHz. However, a good correlation is found between the SE based on average near-field and the SE derived from the radiated power. This study has revealed the near-field shielding properties of SiP, which is helpful for building and analyzing the correlation among the SEs measured by different methods, including the near-field scanning, transverse electromagnetic (TEM) cell and reverberation chamber.

Experiment Reproducibility and Electric Field Uniformity in GTEM

Giga-Hertz Transverse Electromagnetic (GTEM) cell is a simpler and cheaper alternative to the full-scale anechoic chamber. It is an equipment of choice in a lot of partial discharge (PD) research, especially for antenna validation. According to a good practice the cell must be validated, or also known as calibrated, for its usability. The calibration term means validating the uniformity of electrical field produced at the point of measurement. This paper introduced a verification technique to be used to validate the integrity of input and response signals. This step is essential so that the reproducibility of the experiment is warranted and also to support the calibration analysis result. It was found that the input and response signals were reproducible and consistent. The calibration analysis on the existing bespoke GTEM showed that electric field uniformity at the prescribed area of testing complied with an established practice. Therefore, the GTEM cell can be used to conduct related experiment.

Wideband transverse electromagnetic cell design and its application in frequency selective surface measurement

An open transverse electromagnetic cell (TEM cell) that covers L-band, S-band, and C-band is proposed in this paper. According to impedance matching theory analysis, the characteristic impedance of coaxial connector and microstrip with air as substrate are considered, which are combined with a taper gradient section to realize the function of TEM cell. The proposed TEM cell was modeled and simulated in CST Microwave Studio. Through full-wave simulation, the proposed TEM cell demonstrates a wideband transmission characteristic, S11 less than −10 dB from 1 to 8 GHz, which is relatively rare among the designs that have been reported. The test flow and data post-processing method are given. To verify the effectiveness of the test method, an example of measuring a classical square slot frequency selective surface that their resonance frequency is 3.7 GHz is designed and simulated in the TEM cell. To verify the simulated results, a prototype is fabricated and measured with the proposed TEM cell. The experimental result demonstrates a good agreement with the simulated result, which indicates that the designed TEM cell has good test performance.