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Examination of the E-field distribution in the MEB 1750 GTEM cell.

Fletcher, S H; Loader, B G; Alexander, M J (2000) Examination of the E-field distribution in the MEB 1750 GTEM cell. NPL Report. CETM 17

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The purpose of this report is to investigate the E-field distribution in a GTEM cell over the range 30 MHz to 1 GHz using a set of calculable dipole antennas and an isotropic field probe, the FP-2000. The vertical E-field along the longitudinal axis of the cell is examined and also the cross-polar components using the 300 MHz and 1 GHz dipole elements. The previously observed longitudinal peak at around 130 MHz is examined in detail. A NEC model was used to calculate the free space antenna factors of the dipoles and to examine the theoretical broadband response. The AF’s calculated by the NEC model agree with the manufacturer’s model (which is an implicit NEC-based model) at the resonant frequency of each dipole pair and so the models were assumed to agree over the appropriate frequency range.
From measurements taken towards the tip of the GTEM it appears that for small Equipment Under Test (EUTs) without cables there may be an advantage in measuring at two different positions at which the longitudinal component appears at different frequencies. The effect of cabling on both vertical and longitudinal E-fields is examined, and the dipole measurements compared with the FP-2000, which uses a fibre-optic link.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CETM 17
Subjects: Electromagnetics
Electromagnetics > RF and Microwave
Last Modified: 02 Feb 2018 13:17
URI: http://eprintspublications.npl.co.uk/id/eprint/1544

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