Open Area Test Site Research Articles

Suppressing thermal runaway propagation of nickel-rich Lithium-ion battery modules using silica aerogel sheets

Suppressing thermal runaway (TR) propagation within Lithium-ion battery (LIB) modules/packs/systems is one of the key factors to ensure the safety utilization of electric vehicles and energy storage systems. This contribution aims at introducing Silica Aerogel Sheets (SAS) into high energy density modules to suppress the TR propagation. The SAS, synthesized via a sol-gel process followed by supercritical fluid drying, possess almost an ideal thermal insulator characteristic due to the low thermal conductivity of 0.020 W/(m·K) at room temperature. The SAS are inserted between two adjacent pouch cells (LiNi0.86Co0.07Mn0.07O2/graphite, 320 Wh.kg−1) to assemble high energy density modules. A single pouch cell, subjected to the TR test with an Accelerating Rate Calorimetry, releases a huge amount of heat energy (1083 kJ/kg) with the maximum temperature beyond 800 °C. In the open area test site for TR propagation experiments, it can be observed that violent jet and flame burst from the cell, which is designed to undergo TR first and trigger the TR propagation of the modules. The results show that only one single layer of SAS cannot stop the TR propagation or fire spreading. However, more layers of SAS (three in the experiments) can successfully suppress the TR propagation and block fire progression. The temperature of the adjacent cell only reaches 105.4 °C. Therefore, the SAS with acceptable thickness can suppress the TR propagation successfully to improve the safety of the LIB modules.

A review of measurement of electromagnetic emission in electronic product: Techniques and challenges

Nowadays, electronic products are being used extensively in many fields and applications. The dense population of electronic devices in human life has become a challenge for microwave engineers to ensure that their products can meet the Electromagnetic Compatibility (EMC) standards. Complex electronic products with smaller sizes and denser components will be a challenge for compliance with EMC standards. In addition, the occurrence of non-stationary emission at certain operating modes becomes a challenge for analysis. Error in analyzing EM emissions will make the products unable to meet the requirements of EMC standards; hence, they will be prohibited to be marketed. Currently, there are two methods of emission analysis, i.e. by measurement and modeling or computation. There are some problems, however, in the analysis of EM emissions regarding the area of test, complexity, DUT positioning error, installation cost, and time consumption. In this paper, the analysis techniques for EM emissions including Open Area Test Site (OATS), Anechoic chamber, Transverse Electromagnetics TEM Cell, Compact Antenna Test Range (CATR) and near field scanning are reviewed comprehensively. This survey covered EMC standards, principles of EM emission measurement techniques, advantages and disadvantages of EM emission measurement techniques, studies and applications of each technique, recommendations for which technique to be used, and challenges for future research in EM emission measurement. The final section of this paper discusses the challenges for near-field measurements related to the non-stationary emissions phenomenon. This papers also presents the challenges of how to detect and characterize them.

Calculation of Normalized Site Attenuation for Calculable Dipole Antennas

When a pair of calculable dipole antennas (CalDAs) with a 3-dB hybrid balun is used for a validation test of a constructed open area test site (OATS), the theoretical normalized site attenuation (NSA) curves of an ideal OATS for the CalDAs are required. This paper presents a method to calculate this theoretical NSA in the frequency range of 30 MHz to 1 GHz. The theoretical NSA was directly derived using the power mismatch and dissipative loss concepts of an NSA measurement system. Accurate antenna factors (AFs) above the ground plane were also needed and calculated to obtain the theoretical NSA. When free-space AFs are used to determine the measured NSA, AF correction factors known as mutual impedance correction factors are needed. Both free-space AFs and AF correction factors were also considered.

Search for suitability of relatively narrow test sites for antenna calibration according to ANSI C63.5-2006 standard site method – A case study in Istanbul-Turkey

In today’s world, electromagnetic compatibility (EMC) tests are of primary significance, increasing the importance of accurate measuring of EMC antenna factors. The standards for antenna calibrations require near-ideal conditions as empty space above ground plane with very large dimensions. We investigate the possibility to use the open-area test site (OATS) of Turkish Standard Institution (TSE) for antenna calibrations, which is generally used for EMC product tests. Although the physical dimensions of the site are limited and the dominating component in the overall uncertainty is the one due to site conditions, the measurements and the uncertainty budget put forth that the site can be used for calibrations according to ANSI-C63.5-2006. We hope this study will be significant in directing experimenters to consider the aspect that one should not expect near-ideal conditions to start the calibration process. In this context, a detailed uncertainty analysis is performed together with a site validation process.

Calculation of Site Attenuation for Calculable Dipole Antennas

This paper presents a method for calculating the site attenuation (SA) of an open-area test site (OATS) for a pair of calculable dipole antennas with a 3-dB hybrid balun in the frequency range of 30 MHz to 1 GHz. The SA was directly derived using the concept of power mismatch and dissipative loss from the SA measurement system instead of the concept of substitution loss. Two types of SA formulas using the power loss concept on the treatment of the OATS are presented. The first is the SA formula related to knowing only the value of the SA. The other is the SA formula that analyzed the effects of each part of the SA. Additionally, the constituent losses of the SA measurement system are discussed using the derived SA formula. The analysis of the results showed that the SA could be successfully characterized individually from the loss of the OATS. It also showed that SA is expressed as two kinds of losses: the balanced portmismatch losses of transmit and receive baluns and the half-space dissipative loss. The resultant SA showed good agreement with the results calculated from the S-parameters as well as with the measured results.

Comparing Open Area Test Site and Resonant Chamber for Unmanned Aerial Vehicle's High-Intensity Radiated Field Testing

Open area test sites (OATS) have been traditionally employed for aircraft electromagnetic compatibility certification tests because of the large size of these items. In this regard, unmanned aerial vehicles (UAVs) have emerged in the last years and, albeit being sometimes notably smaller, yet they have to accomplish for the same certification process. This paper investigates into the possibility of using a reverberation chamber for performing two aircraft low-level coupling tests, namely, low-level direct drive and low-level swept fields, and compares the results with those obtained in an OATS, in both cases using a representative part of a UAV.

A Fast Way to Accurately Calibrate Tunable Dipole Antennas at VHF

A fast method is proposed and verified experimentally to calibrate tunable dipole antennas. An adapter is introduced to convert a commercially available balun for dipoles into a three-port network; this allows its S-parameter to be accurately measured. Using this process, the antenna factor, site attenuation (SA), as well as balance, can be calculated with the method of moments (MoM). The calculated SA is verified by precise measurements on a high-performance open-area test site, and the differences are less than 0.3 dB from 30 to 282 MHz. As an application, the mutual impedance correction factors are calculated with the MoM for tunable dipole antennas. Furthermore, the three balun method is proposed to measure the loss of a balun with two simple adapters, which provides a faster method to calculate the free-space antenna factor ( F a). The new method will reduce the time from several days to several hours to calibrate a pair of tunable dipole antennas. A clearer traceability chain for measuring F a is illustrated, too.

Cancellation of interference for emission measurement in open area test site

This paper proposes a technique for implementing the concept of a virtual chamber for radiation emission measurements in time domain. At present measurements for electromagnetic emissions are carried out either with FFT based analyzers or with a conventional-hybrid spectrum analyzer based on heterodyning where interested band of frequencies is swept in the radio frequency range in an anechoic chamber. This method requires a large measurement time especially for wide band frequency measurements; therefore such methods cannot guarantee reliable results in open area. The difficulty lies in the interference cancellation from random sources for prolonged measurement duration.In this paper time domain measurement technique for electromagnetic emissions at open area test site has been proposed, designed, implemented and tested in a laboratory environment. The proposed technique captures multichannel signal from interference sources and equipment under test (EUT) simultaneously on different antenna ports. The continuous signal streams sampled at a very high rate before being fed to the stochastic gradient based adaptive filter. This materializes the cancelation of interference generated by various electronic sources using advanced digital processing techniques. The factors influencing the exactness in estimating interference are discussed in detail and cancelation of interference over the range of frequency (DC-1GHz) has been simulated. The simulation results exhibit how the proposed technique can revoke different kinds of interferences like continuous or transient, narrow or broad band. The performance evaluation of this method is verified through experiments conducted on real electronic appliances in open space environment and cross validated in an anechoic chamber up to 1GHz. The outcome of the research demonstrates the cancellation of both generated as well as naturally existing random interfering signals in an urban site polluted with electrical noise. The results substantiate the accuracy and usefulness of this new method for the measurement of radiation emissions and electromagnetic compatibility in accordance with CISPR standards. Pre-compliance electromagnetic compatibility testing is realized with this work without the need of an expensive anechoic chamber and with a reduced measurement time compared to the conventional measurement system.

Evaluation of radiating-source parameters by measurements in Faraday cages and sparse processing

Abstract We have developed an algorithm that enables characterization of radiating sources by amplitude measurements in a Faraday cage. The algorithm uses equivalent dipoles and exploits electromagnetic scattering from the cage walls. To extract the parameters of the equivalent dipoles, we use sparse processing. We have verified the proposed approach by comparing experimental results obtained in an anechoic chamber and in a Faraday cage. In this way, we have shown that the Faraday-cage measurements may be used as a low-cost alternative to the standard electromagnetic-compatibility test sites such as (semi)anechoic chambers and open-area test sites.

On-Site Radiated Emissions Measurements in Semireverberant Environments

Radiated emission tests are generally performed in either free space, reflection-free environments, such as an open area test site or semi- or full-anechoic chambers, or in reverberation chambers. This paper describes measurements in semireflecting environments such as an office, a workshop of a large industrial apparatus or installation. The objective is to develop test methods and associated correction factors and uncertainties for measurements which are performed on-site, near large industrial apparatus which cannot be moved to an EMC laboratory. The measurement technique is based on reverberation chambers and tools such as insertion loss, quality factor, as well as a goodness of fit test were used to perform the test site analysis. The advantages and drawbacks of on-site measurements of large apparatus are discussed. A simplified, but not limited to perfect reverberation chambers, method of finding the measurement uncertainties was used to calculate the errors associated with imperfect reverberation and field uniformity, as well as the influence of noise and equipment nonlinearities. The results are given in form of a guideline, concluding that such measurements are possible.

The Measurement and Uncertainty Analysis of Antenna Factor of Microwave Antennas Based on Standard Site Method

A method of Standard Site Method (SSM) in the American National Standards Institute’s ANSI C63.5 is described in the frequency ranges from 30 MHz to 1000 MHz. And a measurement system is set up for determining antenna factors (AF) of antennas on an Open Area Test Sites (OATS). AF of antennas including log-periodic antenna and biconical antenna is measured with SSM method by Shanghai Institute of Measurement and Testing Technology (SIMT), which shows good agreement to data measured by National Institute of Metrology (NIM). In the end, it analyzes the measurement uncertainty of SIMT in the 30 MHz to 1000 MHz frequency band and does comparison to that of NIM.

On the Influence of Scattering From Traffic Signs in Vehicle-to-X Communications

As an important scatterer in vehicle-to-X (V2X) communication scenarios, traffic signs frequently appear along roads and can affect the propagation channel appreciably. Although traffic signs can be considered as an important part in such scattering scenarios, knowledge of their bistatic radar cross section (RCS) is still absent. This paper presents an integration of the analytical models, full-wave simulation, measurement, and validation of the bistatic RCS of three types of representative traffic signs for V2X communication. First, the total RCS of the traffic signs is calculated by summing up the field contributions of the individual parts with their own phase relationships. Furthermore, simulations using full-wave analysis are performed to validate the analytical models for RCSs in the far field under plane-wave illumination. Since the high-frequency calculation techniques used here are applicable only under plane-wave excitation, the traffic-sign parts are divided into small elements, where this precondition is locally valid. Measurements are conducted in an open-area test site at the National Metrology Institute of Germany to validate the model in the near field (spherical wave from a point source). Corresponding comparisons show that the method of decomposing the traffic sign into small parts supports an effective way to embed the analytical models into ray-tracing tools, thus improving propagation modeling in V2X communication.

The Use of Equivalent Model and Numerical Simulation for EMC Analysis in Hospital Environments

This paper promotes the use of prediction methods as an alternative tool for evaluating and managing electromagnetic compatibility (EMC) in hospital environments. Radiated emissions originated from medical equipment are modeled based on open area test site measurements, and they are applied to numerical simulation using transmission line matrix method (TLM). TLM simulation is performed to include not only the multipath effects provided by obstacles, but also the interaction and coupling of all different sources/models operating simultaneously on the environment under test (a typical operating room). This approach provides a useful tool in order to assess electromagnetic profiles established within the room area, and it allows implementing optimization processes such as genetic algorithms (GA). GA is employed to evaluate many different placements of medical equipment within the environment under test. A fitness function is defined to minimize the average electric field inside the room, providing a better equipment disposal to develop a preliminary EMC management program.

Alternative radiated emission measurements at close distance in industry

Radiated emission measurements are always performed in laboratories at Open Area Test Sites or in anechoic chambers at 10 or 3 m in accordance with the standard EN55022 or other similar standards. However, it is not always possible to use laboratories because of some limitations. If the Equipment Under Test has large dimensions or heavy, it is not possible to use laboratory facilities during tests. As a consequence, on-site radiated emission tests are required in industry. However, radiated emission tests have many challenges in industry such as background noise, uncontrolled reflections and narrow testing environment, for that reason EMC testing is very challenging at 3/10 m and close distance testing at non-standard distances becomes unavoidable in industry. In this research, we have experimentally investigated the relation between measurement results at close distance and standard distance for certain types of antennas. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:294–303, 2016.

Method for EMC antenna factor temperature error correction

In order to reduce the influence of the outfield environmental temperature and improve the measuring precision of electromagnetic compatibility( EMC) test equipment,a method for antenna factor temperature error correction was presented. Firstly,according to the principle of two antenna calibration with 1 m distance,the antenna receiving characteristic influenced by temperature control device made by radome material under the condition of near field was theoretically deduced. Combined with the simulation analysis and test results proved that the test error can be controlled in the permitted range by using the temperature control device. Secondly,on this basis the antenna factor variation with temperature and temperature error correction surface for typical antenna was obtainedby the actual test. In the end,the method was verified by comparing the test result uder standard conditions with the test result under the open area test site( OATS) condition.The results prove that this method can expand the environmental temperature range of use from- 40℃ to 50℃by antenna factor temperature error correction on the premise of not reducing measurement precision,and suitable for the antenna factor temperature error correction in EMC double cone antenna and log periodic antenna and the double ridged horn antenna,etc.

Differential site attenuation without using free space antenna factor

Differential site attenuation (DSA) to verify the performance of electromagnetic compatibility (EMC) facilities, open area test site and semi-anechoic chamber, without using a calibrated free space antenna factor (AFFS) is proposed. In the evaluation of EMC facilities, the AFFS is one of the main uncertainty contributions. The measured results are reported and compared with the current site attenuations. It is shown that the proposed DSA has good discrimination capability in verifying the performance of EMC facilities.

Accurate Capacitance Extraction in Equivalent Capacitor Substitution Method (ECSM) for Monopole Antenna Calibration

Free-space methods for EMC antenna calibrations at Open Area Test Site (OATS) are not suitable for monopole antennas because of corresponding large wavelengths. The Equivalent Capacitor Substitution Method (ECSM) is adopted in ANSI and CISPR standards. One of major uncertainty factors of ECSM is the accuracy of capacitance. A novel capacitance extraction method based on full-wave impedance modelling is proposed in this paper, which is more accurate than conventional analytical formulae and experienced values, especially for practical monopole antennas, with a telescopic rod, or with a finite ground plane. A projection based model order reduction method is then utilized to achieve a compact macro-model. The capacitance value can be determined from the input impedance which is given by the macro-model output. The scheme and computational methodology of a developed calculation tool are introduced, together with some practical calibration data which indicates the effectiveness of the proposed methods.

A novel single feed of circular polarized antenna and open area test site measurements for 2.4 GHz application

ABSTRACTA novel single feed of the truncated edge circular polarized array antenna for 2.4 GHz applications with high gain is analyzed and proposed. The presented circular polarized antenna is comprised of four patches as its radiating elements and fed by a single coaxial connector at the ground layer. Dimension‐wise, the proposed antenna is designed with compact size of 56 × 69 × 1.6 mm3. It is notified that 45° of patches' truncated edge, 45 mm element spacing of Y‐axis, and 39.5 mm element spacing of X‐axis collectively contribute to the circular polarization capability. The prototype of the antenna has a right‐hand circular polarization with an axial ratio of 2.019 in particular of 2.4 GHz. Additionally, the similarity patterns of E‐plane and H‐plane of the antenna prove its circular polarization capability. Further, the proposed antenna seems to have an omnidirectional pattern eventhough using a full ground plane and improved the effective coverage angle. With the measured gain of 5.35 dB and the reflection coefficient of −14.16 dB, the proposed antenna has big potential for Wi‐Fi and biomedical application. The antenna prototype performance is verified, and the experimental result is presented and discussed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1337–1344, 2014

Completed careers [David Fry obituary

The Associate Editor reports that David Fry succumbed as a result of a tragic accident at an Open Area Test Site (OATS) in California. David Lee Fry was born August 17, 1956, in Victorville, California, and was married in 1992. David and his wife Theresa had three children, all living in Iowa. David, 57, died Monday, June 30, 2014, during a weather-related accident at the OATS site in Fairfax, Iowa. David was employed by Intermec (now Honeywell) for 37 years as an EMC engineer. He was an active member of the Knights of Columbus and enjoyed shooting pool, riding his motorcycle and traveling. Tributes from his colleagues are included.

Construction of Screening Area in Open Area Test Site

The screening board using wall materials is effective to evaluate wireless system fundamental characteristics in the outdoor environment. In this letter, the electrical parameters of lath metal board are evaluated using a simple experimental value and ray-trace simulation results. Using evaluated parameters, the screening area using lath board can be calculated using ray-trace simulator.