Radiated Susceptibility Testing Research Articles

Equivalent test method for continuous-wave high-field effects of aircraft equipment in four-core RVVP cable coupling channel

In situations where there is ample space, constructing a high-field electromagnetic environment for radiated susceptibility testing of aircraft equipment can be difficult. This has necessitated the need for an equivalent test method. To address this issue, the response calculation models of the internal two-core pairs under radiation and injection conditions are established for the coupling channel of the four-core RVVP cable. The equivalent linear relationships between the two injected sources and the field intensity are derived, providing the foundation for obtaining equivalent injection sources and conducting linear extrapolation. Building on these findings, a specific equivalent test technology is proposed, based on the double bulk current injection. This technology is then verified through a pass-through load test for the continuous-wave high-field effects of aircraft equipment in the four-core RVVP cable coupling channel. The results of the tests demonstrated that the equivalent test method can accurately equate the high-field effects test with a maximum error of less than 1 dB. Moreover, it is applicable to nonlinear systems.

Analytical Approximations for the Maximum-to-mean Ratio of the E-field in a Reverberation Chamber: A Review

The expected value of the maximum value of the rectangular E-field is important in radiated susceptibility testing in a reverberation chamber. In this paper, different forms of equations for the maximum-to-mean ratio of the rectangular E-field are reviewed. Important derivations are summarized and detailed. It is interesting to note that some series which could be difficult to deal with from mathematics could be solved efficiently from physical point of view. The relationship between the independent sample number N and the parameters in generalized extreme value distribution is also given.

Radiated Susceptibility Assessment of Interconnected Systems Within Dual Reverberation Chamber

The interconnected systems (ISs) are commonly exposed to electromagnetic environments with different maximum field levels, and the measurement technique on how to perform radiated susceptibility (RS) test is one of the most attractive research topics of the electromagnetic compatibility (EMC) community. In this work, the dual reverberation chamber (DRC) is used to reveal the potential EMC issues of the IS, which also provides a comparison with the RS tests performed in a conventional RC. By using a typical IS on the ship, we highlight the evidence supporting IS to conduct the RS tests in the DRC. Taken together, the results show that the IS will be more sensitive within the DRC and expose more acute EMC problems on one hand; on the other hand, the IS also presents a larger probability of sensitivity.

Efficient Use of a Hybrid Chamber for Radiated Susceptibility Tests

This letter describes the design and operation of a novel type of hybrid chamber used for radiated susceptibility tests. This is a semi-anechoic chamber with the possibility to install a vibrating intrinsic reverberation chamber inside. This testing environment can be used for the execution of the radiated susceptibility tests using both the deterministic and stochastic methodologies but without changing the test location, nor moving the device under test with its auxiliary equipment. This allows test engineers to combine the advantages of both reverberation and semi-anechoic chambers with a minimum effort, making it a very practical, cost- and time-efficient solution. The electric field into the reverberation chamber is monitored by eight electric field probes, permitting the closed-loop control of the electric field strength level and an efficient real-time analysis of the performance indicators discussed in this letter.

Unshielded Two-Wire Circuit Systems under Weak Unbalance for High-Intensity Radiated Field Radiated Susceptibility by Double Bulk Current Injection

In unshielded two-wire circuits of weapon systems, the equipment at both ends of the cable needs to be tested at the same time. The theoretical model of substituting double bulk current injection (DBCI) for high-intensity radiated field (HIRF) electromagnetic radiation is established, which aims to calculate the relationship between the injection excitation voltage source and the radiation field intensity. Additionally, the conditions required for linear extrapolation is clarified. Subsequently, the test method of using DBCI for the HIRF radiated susceptibility (RS) is proposed. Next, the verification of the CST studio and the pass-through load test are performed. All results shows that the test method can avoid the influence of the impedance parameters of the two equipment at both ends, which can be applied to nonlinear terminals for the HIRF RS test.

Detection and Identification of System Level Soft Failure Induced by Radio Frequency Interference in Small UAV System

A system level methodology is presented for soft failure detection and analysis in small unmanned aerial vehicle (UAV) system, induced by radio frequency interference (RFI). This method includes a radio frequency test system based on the equivalent dynamic test method, and soft failure detection and identification method based on ground control station observation records and system log analysis. By designing signal forwarding system for global positioning system, the equivalent dynamic flight state of the UAV is realized. Through the application of standard radiated susceptibility test methods, the effects of RFI with multiple interference levels covering the frequency range from 2 MHz to 3 GHz on small UAV systems have been investigated. RFI is coupled into the UAV system through the antenna coupling and cable coupling. Soft failure modes are classified and failure analysis is mainly carried out through system log analysis, combined with full-wave simulation analysis, the root cause of the soft failure is determined. The understanding of the soft failure mode and susceptibility is beneficial to the design of UAV system, improving the robustness of software and hardware.

Risk to Declare EMC Compliant a Faulty EUT During Radiated Susceptibility Tests Performed in an Undermoded Reverberation Chamber

This article investigates the risk to declare compliant a faulty equipment under test during a radiated susceptibility test performed in a reverberation chamber (RC) working imperfectly, i.e., in the lowest frequency range when the chamber is undermoded. The results obtained from an extensive measurement campaign are compared, using the same worst-case approach, to a probabilistic model proposed recently for well-stirred RCs. Below the frequency when the RC can be assumed to be well-stirred, the variance (or the standard deviation) of the electromagnetic field (or of the induced power on the equipment) may strongly differ from the ideal case, depending on the effect of the stirring process and of the modal density. If the variance is low, the test is, as expected, quite meaningless and it makes sense to avoid this corresponding frequency range. However, more surprisingly, if the variance is higher than the one observed in ideal conditions, the risk is paradoxically reduced for weakly susceptible equipment (but increased for highly susceptible ones). Indeed, this higher variance makes the appearance of a strong amplitude of the disturbance for a given stirring configuration more probable. This article is considered as an incremental step in the understanding of the RC behavior from the point of view of radiated susceptibility testing, particularly when the RC is undermoded, a frequency range generally used to perform this kind of tests.

Radio frequency susceptibility test of Beidou airborne receiver

The radio frequency susceptibility testing method of RTCA/DO-160G section 20 has been widely utilized to verify the reliability of airborne equipments in civil aviation. However, there are only a few of theory analysis and practical test of Beidou airborne equipment based on the procedure of radio frequency susceptibility test originated from RTCA/DO-160G, the research of radio frequency susceptibility test stemmed from RTCA/DO-160G is aiming at provide theoretical reference and practical bases for civil Beidou airborne receiver. Firstly, a theoretical model of calibration for conducted susceptibility and radiated susceptibility is derived and validated its effectiveness, the derived theoretical model indicate that choosing a suitable injection probe that meets the requirements of standard is much more important than the choose of a high power amplifier, a method for estimating the input power of antenna is also obtained under far field zone. Secondly, an equivalence model based on the susceptibility probability is formulated between the anechoic chamber and reverberation chamber method of radiated susceptibility test, the theory and experimental results show that the model can predict the difference between these two test methods well. Finally, a susceptibility evaluation model is constructed in terms of the needed test signal. The practical minimum radiated susceptibility threshold for continuous wave and pulse modulated signal are 5 V/m and 40 V/m, which indicates the receiver shows a better endurance to pulse interference than continuous wave.

Alternative radiated susceptibility test methods at unit level

This article briefly illustrates and discusses the possibility to develop alternative, simplified test methods for radiated susceptibility testing at unit level for the aerospace sector. The rationale here discussed, and the alternative test methods here illustrated, are targeted to the development of a testing approach with deeper physics' sense, quicker and less expensive in order to help the industrial design process of equipment for spacecraft. The theoretical basis of this analysis is the possibility to enforce equivalence (in terms of common mode current) among the effects due to field-to-wire-coupling, bulk current injection and crosstalk, under suitable assumptions. Two dual approaches are considered, one aimed at achieving deterministic equivalence, the other enforcing equivalence in statistical terms. Pros and cons of the proposed alternative test methods are discussed by illustrating the outcomes of ad hoc setups and a wide experimental campaign.

Crosstalk-Based Test Setup Reproducing Radiated Susceptibility Effects in Wire Bundles

In the development of alternative test methods for pre-compliance radiated-susceptibility (RS) investigations, it is proven that a special test setup, involving an additional wire placed in proximity of the cable under test and fed by two radio-frequency generators, can reproduce through crosstalk (XT) the same terminal voltages/currents induced in the standard RS test setup, on condition that those generators are properly controlled in magnitude and phase. Such a test setup does not require expensive facilities like anechoic chambers and powerful amplifiers to feed antennas, therefore it represents a fast and cheap alternative to get feedback on radiated immunity in the early-design stage, before the formal RS assessment carried out according to standards. While in past literature works the equivalence between XT and RS was demonstrated for some simple cables like a single bare wire or a differential pair, this paper presents a new XT-based test setup suitable for the practically relevant case of a complex bundle of dielectric-covered wires. To this aim, two different formulations of feeding conditions are proposed, one more rigorous, based on multiconductor-transmission-line modeling, and one approximate, based on bundle-reduction techniques. The performance of both the equivalence schemes is assessed and discussed in the frequency range between 1 MHz and 1 GHz.

Design and Evaluation of Test Waveforms Emitted by Portable Electronic Devices for Radiated Susceptibility Testing of Avionic Systems

Assessing the electromagnetic interference (EMI) susceptibility of aircraft systems to transmitting portable electronic devices is challenging. Existing waveforms for susceptibility testing use amplitude modulation: MIL-STD-461 recommends the use of pulse-modulated waveforms, whereas the radio technical commission for aeronautics recommends the use of filtered noise. The ability of such waveforms to represent the EMI of complex communication signals is unknown. This paper expands upon a parameter reduction process for the development of candidate waveforms that are representative of long-term evolution (LTE) signals: single-carrier frequency division multiple access, filtered noise, and pulsemodulated waveforms are proposed as candidate signals for radiated susceptibility testing. The waveforms were evaluated by measuring the EMI response of avionic equipment that was exposed to the waveforms in an anechoic chamber. The measured data were analyzed to determine whether the bandwidth and the peak-to-average power ratio had significant effects on the measured EMI compared to real LTE signals. The proposed method is general and can be used for other communication standards.

On the Risk to Declare EMC Compliant a Faulty EUT During Radiated Susceptibility Tests in Reverberation Chambers

This paper presents a general method, experimentally validated, highlighting the influence of the number of stirring configurations used during radiated susceptibility tests performed in reverberation chambers in terms of reliability and confidence of the obtained results. This Monte-Carlo based approach (with routines available on demand) computes the risk to declare compliant from an electromagnetic compatibility (EMC) point of view a faulty equipment under test. This risk is calculated according to the number of stirring configurations chosen for the test and to the uncertainty of the electromagnetic field strength applied on the equipment. The proposed method is shown to be applicable for any equipment independently of its size and directivity (or more precisely its receiving polarization pattern). Overtesting is shown in this context to be a promising solution able to increase the confidence of the users about the EMC compliance of tested equipment. The paper also illustrates the possibility to extract the minimum susceptibility level of a valid EUT as a function of the testing conditions.

Practical papers, articles and application notes

Isotropic field sensors are essential to monitor the electric field strength in radiated susceptibility testing. Usually these are active sensors that require periodic calibration. The first paper "Experimental Investigation of D Dot Sensor Performance in Frequency Domain" contributed by Rakesh Kichouliya, Sandeep M. Satav and D. C. Pande from Defense R & D Organization, India, proposes an asymmetrical conical dipole (ACD) type sensor for frequency domain field measurement in radiated susceptibility testing. The sensor has no active electronic circuitry and therefore eliminates the need of periodic calibration.

Experimental investigation of D dot sensor performance in frequency domain

Isotropic field probes are used to characterize the electric field in radiated susceptibility testing of electronic systems. These probes are required to be periodically calibrated by the original equipment manufacturer, which is essential as per test requirements. Getting a probe calibration done is a time consuming process for an EMC laboratory. If the probe calibration is not done periodically, than the validity of test results are questionable. In this paper, we have demonstrated to use the ACD type D dot sensor in frequency domain in place of isotropic probes, in radiated susceptibility testing. The D dot sensors do not have active electronic circuitry and therefore are not required to be calibrated periodically.

Bulk Current Injection as an Alternative Radiated Susceptibility Test Enforcing a Statistically Quantified Overtesting Margin

Experimental results are presented in support of the use of bulk current injection (BCI) as an alternative technique to unit-level radiated susceptibility (RS) verifications up to 1 GHz. The rationale for the correlation of BCI/RS test levels is grounded in the concept of overtesting (OT), which quantifies the excess of disturbances injected by BCI with respect to RS. Previous works showed that OT is a random variable, owing to unknown and uncontrolled setup parameters including the common-mode impedance of the equipment under test. The cumulative distribution function (cdf) of OT was shown to be predictable, by means of reasonable statistical assumptions and simple circuit models. This paper fills the gap between that simplified theoretical analysis and the complexity of real-world test setups. To this aim, an ad hoc structure mimicking typical wiring harness and equipment for aerospace applications is tested with BCI and RS to collect several results in terms of power injected/induced in the terminal units. The obtained datasets are processed to infer the empirical cdf of OT. Results are compared with theoretical predictions and properly discussed to point out the correlation between BCI and RS achieved in different test cases (vertical/horizontal antenna polarization, unshielded/shielded cables).

A Rationale for Statistical Correlation of Conducted and Radiated Susceptibility Testing in Aerospace EMC

A conducted susceptibility (CS) test based on bulk current injection (BCI) is designed to ensure correlation of outcomes with typical radiated susceptibility (RS) test procedures foreseen in aerospace/defense standards. It is first shown that deterministic equivalence of RS and CS is awkward due to the lack of knowledge (under common testing conditions) of the common-mode impedance of the equipment under test and the auxiliary equipment. Subsequently, such unknown and uncontrolled setup parameters are treated as random variables, and a statistical rationale is developed to correlate the outcome of CS and RS tests. In particular, the proposed BCI test levels (probe calibration current versus frequency) are related to cumulative distribution functions which quantify the probability of overtesting (i.e., the excess of injected interference) with respect to RS.

Dual‐port pulsed differential‐mode current injection method for high‐level electromagnetic pulse radiated susceptibility testing

A dual-port pulsed differential-mode current injection (DPDCI) method is proposed for high-level wide-band electromagnetic pulse (EMP) radiated susceptibility testing of interconnected systems. By employing the designed wide-band differential-mode (DM) coupling device, the susceptibility of the equipment under test (EUT) at both ends can be assessed at the same time. In order to enforce the equivalence between EMP radiation and DPDCI, the methods to obtain the waveforms of the two equivalent injection sources and their time delay difference are proposed. By using the linear extrapolation method, the results for high-level EMP radiation can be reproduced by DPDCI even if the responses of the two EUTs are non-linear. To confirm the effectiveness of the proposed method, the conversion of common-mode interference into DM disturbance on the cable inside the EUT is assessed by experiment and the impact of connecting the injection devices into the system is discussed. By using a typical interconnected system composed of a coaxial cable and typical non-linear equipment at both ends, the feasibility of the proposed method is verified.

Polarization of the Electromagnetic Field Radiated From a Random Emitter and Its Coupling to a General Antenna

The polarization coupling between a random emitter and a measurement antenna is uniformly distributed between 0 and 1, independent of the receiving polarization of measurement antenna in use. The polarization efficiency when performing a radiated susceptibility test on the same object, is also uniformly distributed between 0 and 1.

Numerical Simulation of Reverberation Chamber Parameters Affecting the Received Power Statistics

This paper presents a reverberation chamber (RC) numerical modeling based on a discrete plane wave representation. In particular, the attention is focused on those parameters that may influence the field statistics. It is shown that a random choice of the angle of incidence, the initial phase, and the polarization in a particular range and a proper choice of the number of the plane waves allow us to reproduce the same behavior of experimental data. Both experimental and numerical field data are checked applying the Anderson–Darling (AD) test. More precisely, we count the frequencies where the received power statistics is rejected by the adopted goodness-of-fit test. This paper shows a correspondence between numerical and experimental parameters affecting the occurrence of the rejected frequencies, also giving a probability density function for the observed occurrence. The analysis is completed showing that the AD test rejection does not compromise the chamber use for typical radiated emission or radiated susceptibility tests.

Including Directivity in Reverberation Chamber Radiated Susceptibility Testing

The susceptibility of electronic equipment against electromagnetic irradiation depends on irradiation direction and polarisation. We show how this dependency can be taken into account when performing a radiated susceptibility test in the reverberation chamber. In the reverberation chamber the stress onto the equipment under test increases with the number of independent stirrer positions in the same manner as, in open space the stress onto the equipment under test increases with the number of independent irradiation directions and polarisations.