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We present the basic prerequisites of electromagnetism in flat space–time and provide a description of electromagnetism in terms of the Faraday tensor. We generalize electromagnetic theory to a relativistic setting, introducing the Einstein field equations to describe the propagation of electromagnetic radiation in curved space–time. We investigate the gravitational redshift and derive formulae for the combined effect of the gravitational redshift and the Doppler shift in curved space–time. [ABSTRACT FROM AUTHOR]

The IEC 61000-4-21 and IEEE 299.1 documents report similar but not equal procedures to measure the shielding effectiveness (SE) of enclosures through the use of reverberation chambers. In this article, it is shown that these two measurement procedures can be merged in a single, enhanced, one. In particular, it is shown that the evaluation of the SE of enclosure in Annex H of IEC 61000-4-21, which exploits only mechanical stirring, can be improved by using the hybrid stirring, which includes also the frequency stirring, thus increasing the number of uncorrelated samples. On the other hand, it is shown that at low frequencies the evaluation of the SE of enclosures based on the definition in IEEE 299.1 can be improved through the use of the maximum values of measured powers rather than the average ones. The single, enhanced, proposed procedure provides more prudent SE values than the two standards at the low frequencies, especially for standard IEEE 299.1. The presented measurement approach is supported by results obtained in three different laboratories. [ABSTRACT FROM AUTHOR]

In this study, the authors present the latest developments on the measurements for the shielding effectiveness (SE) of gaskets and materials in reverberation chambers (RCs). A variant method, where the insertion loss of the fixture is achieved from the SE of the fixture with no sample in the aperture is found; it is appropriate for gaskets and for any flat material having a sufficiently high reflectivity at least on one side. A simple and usable condition under which the simplest method for the SE measurements of gaskets and materials in RCs can be used is also given, as well as particular cases where it can be directly applied are shown. This method, whose applicability is enhanced in this study, can be used for gaskets and any flat sample. Such developments simplify measurement setup and associated procedures. Comparisons of results support the methods for the SE measurements of gaskets and material in RCs shown in this study. [ABSTRACT FROM AUTHOR]

In this paper we show a procedure to measure the impedance mismatch of antennas by exploiting the Time Domain (TD) option available in usual VNAs. The procedure can be applied even in the presence of reflecting obstacles in the measurement scenario surrounding the antenna under test (AUT). It is shown that effective application of the procedure requires to fulfill a reduced number of constraints basically involving the distance of the AUT from the nearest obstacle, the response resolution to be set through the TD option of the VNA, and the length of the gating aperture to be applied to the received signal. The proposed measurement procedure is in principle applicable to any antenna. However, it is very easy and advantageous for antennas having short responses in the time domain, such as horn antennas, where the method can likely be applied to frequencies less than 500 MHz. Comparison between the results obtained from measurements performed inside an anechoic chamber (that is, in the absence of reflecting obstacles around the AUT), outside the anechoic chamber, and even inside a reverberation chamber, demonstrate the effectiveness of the proposed measurement procedure. [ABSTRACT FROM AUTHOR]

In this paper, we present an improved model of measurement standard uncertainty of the insertion loss in a reverberation chamber (RC), including frequency stirring. Differently from the previous model, the enhanced one does not require specific conditions on the parameter to be measured. Such an enhancement is applicable for all usable measurement conditions in RCs. Moreover, a majorant is derived, that is obtained under a weak condition on the coefficient of variation of the parameter to be measured. Results from measurements support the validity of both the proposed enhancement and the majorant. [ABSTRACT FROM AUTHOR]

The paper focuses on the reverberation chamber method for the shielding properties evaluation of equipment-level enclosures. The enclosure under test is numerically modeled by an in-house finite-difference time-domain code that is able to predict the field inside the enclosure and the voltage captured by the probe placed inside it. The chamber fields have been modeled by applying the plane-wave superposition. The code is validated by measurements in our reverberation chamber. Subsequently, the effect of probe positioning and length on the induced voltage is analyzed. Finally, the enclosure shielding effectiveness is evaluated by applying two different definitions, and a statistical analysis is carried out, thus allowing an estimation of the measurement uncertainty. [ABSTRACT FROM AUTHOR]