A new technique for shielding effectiveness measurements is the dual VIRC method. In this method two Vibrating Intrinsic Reverberation Chambers (VIRC) are combined together via a common wall with an aperture that forms the interface between them. This particular set-up makes it possible to achieve a very high dynamic range. Advantage of this technique compared to the nested reverberation set-up is that measurements can be conducted much faster and at much lower frequency. Several different approaches to determine the shielding effectiveness are presented. It has been shown that multiple interactions play a role in the particular set-up.
1 Reverberation chambers (RC) are becoming a popular alternative testing facility for a wide range of electromagnetic applications. In order for these tests to have any meaning, we need to ensure that the RC is performing in a desired manner. One common approach for characterizing the RC is based on a measurement of field uniformity in the chamber. In this paper, we present an alternative technique for characterizing a RC, based on the enhanced backscatter coefficient (a quantity analogous to the enhanced backscatter that has been derived for scattering by a random medium) measured in the chamber.
A reverberation chamber (RC), is an economical facility in EMC, because it allows many directions for illumination an object with a higher field strength compared to conventional techniques, for the same input power. For emission measurements there is no need for moving an antenna. The field uniformity and statistical behaviour of the field are important in a RC. This paper presents an evaluation of the performance for three different stirrer designs inside a 1.00 m x 1.30 m x 1.50 m reverberation chamber. The evaluation was done in the frequency range from 300 MHz to 1000 MHz using both simulation and measurement results.
The field strength distribution in real reverberant enclosures, such as plane fuselages or factory interiors, is often too complex for a deterministic approach but can also fall into a category where theoretical assumptions normal for perfect cavities no longer hold. It can vary a lot depending on the actual environment. Estimation of the extreme peak value in real reverberant enclosures is of utmost importance for Electromagnetic Interference (EMI) in terms of either in-situ measurements or EMI threat analysis. It is very difficult to measure it on-site due to usually a low number of available samples. However, as long as these are multipath environments, the peak values can be estimated within a certain confidence based on the average field strength, which can be measured much simpler. In this paper, the maximum-to-average electric field ratio was experimentally analysed in three configurations of two Vibrating Intrinsic Reverberation Chambers (VIRC), simulating the real reverberant environments with different mode densities obtained either by scaling the enclosure in terms of physical or electrical size. In each configuration the influence of the chamber loading, and therefore the quality factor, was analysed in at least 7 steps as a parameter relating the enclosures to each other. 1 hour long measurements were conducted taking samples every 10 ms in each setup, exploiting the randomness of the chamber and allowing for high repeatability of results.
Terrestrial trunked radio (TETRA) is a digital radio standard that was developed to meet the needs of professional mobile radio systems. TETRA is vulnerable to intentional electromagnetic interference (EMI) because of the wireless link. The EMI can easily be front door coupled to the base station via the antenna and cause a denial-of-service of the communication. In this paper, the robustness of TETRA against front door coupled intentional EMI is investigated. Three different interfering mechanisms are discussed: damage of the receiver, saturation of the receiver, and masking the communication signal. The interference mechanisms are fundamentally different and needs to be addressed separately. We present two experimental methods to test the robustness of a base station receiver against different interference mechanisms. Results show that the analyzed TETRA base station is very robust against out-of-channel interference with moderate power levels. Intentional EMI is expected to be in-channel because an adversary will exploit the vulnerable frequencies, and this can disrupt TETRA communications.Index Terms-Bit-error-ratio (BER), gain compression, intentional EMI, robustness, terrestrial trunked radio (TETRA).
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