Herbert, S*; Loh, T H; Wassell, I*; Rigelsford, J*
(2014)
*On the analogy between vehicle and vehicle-like cavities with reverberation chambers.*
IEEE Trans. Antennas Propag., 62 (12).
pp. 6236-6245.

## Abstract

We investigate the possible analogy between electromagnetic wave propagation in vehicle cavities and reverberation chambers. We identify two crucial properties of the reverberation chamber: firstly that the energy retained in the chamber after an impulse input decays exponentially with time; and secondly that above a certain frequency (termed the lowest usable frequency (LUF)), the electric field at a point (sampled over a number of stirrer positions) will be isotropic- i.e., it conforms to a zero mean circularly symmetric complex Gaussian distribution.

To investigate whether the first of these two properties applies to a vehicle cavity we define three cavity types: Type I- the time constant of the exponential decay is the same for all links in the cavity, and the cavity Q factor can be found by a power balance

method; Type II- the time constant of the exponential decay is the same for all links in the cavity, but the cavity Q factor cannot be found by a power balance method; and Type III- any given link is well modelled by an exponential decay, however the time constant varies link to link, and the cavity Q factor cannot be found by a power balance method. Reverberation chambers are Type I cavities, and we find that typically vehicle cavities are Type II or III, meaning that some of the analysis of reverberation chambers can be applied to vehicle cavities.

We also investigate whether it is possible to obtain isotropic fields in vehicle cavities, and find that it is above a certain frequency (the LUF) which is approximately the same as that of a reverberation chamber of the same dimensions.

Item Type: | Article |
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Subjects: | Electromagnetics Electromagnetics > Wireless Communications |

Identification number/DOI: | 10.1109/TAP.2014.2363681 |

Last Modified: | 02 Feb 2018 13:13 |

URI: | http://eprintspublications.npl.co.uk/id/eprint/6457 |

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