Using reverberation chambers for em measurements

Reverberation chambers (RC) are being used for several decades. The main advantage is the high field strength which can be generated, with only modest power. In the last few years the use of RCs became much popular, for testing multi-path propagation for communication links, or testing the coupling of complex fields into transmission lines, as well as testing coupling into objects, and measuring the shielding effectiveness of materials. The costs for setting up a conventional RC, with rotating mode stirrers, is low compared to the cost of anechoic chambers. Existing chambers are making use of a paddle wheel to change the resonant modes in the chamber. A transportable reverberation chamber with varying angles between wall, floor and ceiling and with vibrating walls has been used for testing of many systems. Inside this Vibrating Intrinsic Reverberation Chamber(VIRC) a diffuse, statistically uniform electromagnetic field is created without the use of a mechanical, rotating, mode stirrer. This chamber results in a better homogeneity and increased field strength compared to conventional mode stirred reverberation chambers. The use of flexible material to build the VIRC is making a test facility at even lower cost possible. Furthermore such a VIRC can be built around a test object,and the test object is not to be moved to an anechoic chamber. This can reduce test costs for complex systems. The basic principles of RC and VIRC are explained, and several applications shown

Power tracks instead of planes to reduce radiated electromagnetic fields

The noise voltage in the reference or ground of a printed\ud circuit board is often the cause of unwanted radiated\ud emission. Power supply planes attribute to the noise\ud voltage. By replacing the power supply planes by tracks,\ud the noise voltage in the reference or ground can be\ud reduced, which leads to a considerable reduction of the\ud radiated electromagnetic fields. A potential disadvantage\ud of using power tracks is a decreased power\ud quality, due to a higher ripple voltage. Actual circuits,\ud fed via power planes or power tracks have been designed\ud and measured showing the impact on radiated\ud electromagnetic fields with constant power quality

Printed circuit board permittivity measurement using waveguide and resonator rings

Knowing the frequency dependent complex permittivity of Printed Circuit Board (PCB) substrates is important in\ud modern electronics. In this paper, two methods for measuring the permittivity are applied to the same Flame Resistant (FR4) substrate and the results are compared. The reference measurement is performed by inserting the sample in a rectangular waveguide and measuring the scattering parameters. The other measurement is performed by etching a microstrip ring resonator on the same substrate and measuring the scattering parameters. The results are similar and suggest isotropy and homogeneity

Vulnerability of terrestrial-trunked radio to intelligent intentional electromagnetic interference

The terrestrial-trunked radio (TETRA) specification is produced by the European Telecommunication Standards Institute for private mobile radio systems. We investigated the resilience of TETRA against intelligent intentional electromagnetic interference (IEMI) with low amplitude. Low power signals interfering with the higher layers of the system have the advantage of staying covert. The analysis shows that if the access assignment channel is corrupted, the mobile stations cannot start conversations with the base station. TETRA’s modulation scheme is also investigated. $pi$/4 differential quadrature phase shift keying (QPSK) is interfered with a continuous wave and a QPSK signal. The results show that a continuous wave created the largest error vector magnitude, but creates a peak in the received spectrum. The power of the QPSK signal, however, is distributed over a bandwidth and is more difficult to detect than the continuous wave in the received spectrum. From this, we conclude that the QPSK signal functions is more effective as an intelligent interference signal compared to a continuous wave. In this paper, it is shown that it is possible to create an IEMI that combines the vulnerability in the TETRA protocol with the QPSK signal to disrupt the service to the communication system, while staying covert

In-situ EMI Measurements Using a Vibrating Intrinsic Reverberation Chamber

A new reverberation chamber with varying angles between wall, floor and ceiling and with vibrating walls is used for in-situ testing of a large radar antenna system. Inside this Vibrating Intrinsic Reverberation Chamber (VIRC) a diffuse, statistically uniform electromagnetic field is created without the use of a mechanical, rotating, mode stirrer. This chamber results in a better homogeneity and increased field strength compared to conventional mode stirred reverberation chambers. The experience gained with this VIRC and results obtained using the VIRC for in-situ electromagnetic interference (EMI) testing will be discussed