Browsing by Author "Clow, N."

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    ESA measurements using the hybrid fibre-optic reflection measurement system
    (2009-11-19T16:41:30Z) Morrow, Ivor L.; Clow, N.
    Since the introduction of the Wheeler Cap method to measure the radiation efficiency of an Electrically Small Antenna (ESA), there have been several techniques presented in literature that have either enhanced on the method or provided an alternative technique. This paper presents measurements of the radiation efficiency of an electrically small monopole using the Hybrid Fibre-Optic RF Reflection Measurement System (HRS) integrated into the Wheeler Cap. The HRS isolates the ESA from the measurement system [1]. The ESA’s reflection coefficient can then be measured with the isolated ESA inside the Wheeler Cap and in freespace to determine its efficiency. The HRS is also integrated into a far-field measurement range to measure the far-field radiation pattern of the ESA.
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    Microstrip antennas utilizing MEMS for reconfigurable polarisation states
    (2009-11-19T16:50:15Z) Morrow, Ivor L.; Clow, N.; Schaubert, D. H.
    A modern approach to an established technique is investigated for the electronic control of polarisation of microstrip patch antennas. The control is achieved by placing micro-electromechanical switches (MEMS) at appropriate locations in a patch antenna. The microwave MEMS are used to switch between open and short circuit conditions that allow reconfiguration of the modal fields. Changing the number and location of short circuit field regions changes the radiated field polarisation from linear horizontal to vertical, right hand circular or left hand polarisation. All of the polarisation states are obtained without changing the frequency of operation, input impedance or radiation pattern of the patch an