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Radio frequency (RF) metrology using unmanned aerial vehicles (UAV's) is adding a new dimension to Electromagnetic Compatibility (EMC) investigations. However, the self-induced radio frequency interference (RFI) has limited its applications. We investigate the feasibility of an RFI-quiet multicopter, designed from inception with electromagnetic shielding in mind. This work discusses and tests the...
The characterisation of the dispersion response of an extruded 3D-printed bi-conical antenna is presented using group delay and system fidelity factor (SFF). Measurements were performed in time and frequency domain using two identical antennas. A stable group delay is found and moderate correlation is observed between received and transmitted pulses.
A 3D-printing technique, combined with conductive paints, is investigated for a low-cost methodology in antenna design. The technique is applied on a conical antenna of 41° above a ground-plane using carbon and nickel-based conductive paints. An impedance bandwidth of 20:1 is achieved. Measured normalised-directivity patterns correlate with simulations and the antenna is more than 90% efficient up...
Enclosure shielding effectiveness (SE) is investigated using a reverberation chamber methodology in the time domain (TD). The TD technique is first calibrated on an in-house coaxial airline. A nested-enclosure approach is then presented and checked against a frequency-domain (FD) equivalent evaluation. Good agreement is shown between the theoretical and measured airline results. TD and FD nested-enclosure...
Our research group has contributed to the characterization and mitigation of radio frequency interference (RFI) associated with telescope and infrastructural developments for the Karoo Array Telescope. The Karoo core site is found in the Northern Cape of South Africa. The scale and computational modeling of systems and telescopes, along with actual site testing of RFI and mitigation procedures, will...
Cable transfer impedance is investigated using time domain (TD) techniques to reduce measurement duration. Two methods have been used: the current injection and the mode-tuned reverberation chamber technique. Initial transfer impedance results on RG-58 coaxial cable show good agreement between TD and frequency domain (FD) for both setups. The gated-TD approach permits larger frequency bands to be...
The Square Kilometre Array (SKA) is to be the most sensitive radio astronomy receiver ever constructed. The Karoo Array Telescope (KAT) region, part of an SKA bidding site in South Africa, has been proclaimed a radio quiet zone. This paper describes several contributions our group has made to the strategies used in the management of environmental RFI and self-generated emissions. Additionally, we...
We study the performance of a reverberation chamber for coaxial cable transfer impedance determination. The chamber is calibrated according to the relevant IEC standard 61000-4-21. The results are evaluated from radiated power measurement of a standard radiator, using an Open Area Test Site equivalent E-field approach. The transfer impedance of a 50 Ω coaxial air-line is tested with the calibrated...
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