2009 Tests, Silsden, West Yorkshire, U.K.
In the period August 2008 to September 2009 Communications Dynamics (I.o.M.) Limited (or CDL) and Kabbary Antenna Technology (Egypt) Ltd. (or KAT) co-operated in the construction and testing of various CFA's at Silsden in West Yorkshire, U.K. The testing was carried out by both CDL/KAT and an independent company, Arqiva.
The published results used an 8m high CFA at ground level, and also mounted on a 5m high platform. The frequency used for these tests was 1593 kHz (188.24m); using a 5W carrier wave only, no modulation. The reasons for the platform were to simulate installation of a CFA antenna on the roof of a studio or transmitter building, and, as stated in the report, the CFA would not work on the ground; this also made it easier to adjust the CFA settings to enhance radiation in the ground wave at low elevation angles.
The test results also clearly show that the near electric fields (displacement current) do not extend further from the CFA than its very small elevated ground plane. With the classical tuned monopole the displacement current extends as far away as half a wavelength from the mast independent of its height; this is also the maximum distance covered by the ground surface currents closing the antenna electric circuit. For this reason the classical tuned monopole needs a much larger high conductive ground plane than is needed for the CFA to maintain a high level of efficiency. This is a clear indication of Maurice C Hately's controversial PVS technology that he developed from his analysis of the near field effects around the classical half wave dipole.
It was concluded that the CFA worked slightly better than the equivalent 1/4 wave vertical monopole (When situated on the platform).
The CFA used in the Silsden tests — an 8m high CFA — is approximately 1/6 the height needed for the equivalent 1/4 wave monopole (1593 kHz = 188m wavelength, 1/4 wavelength = 47m, CFA height is 8m). This shows that the original claim for the CFA — having an equal performance for 1/10 the height of a conventional 1/4 wave monopole — is not correct; but still an impressive size to performance ratio has been shown.
Even on a 5m platform, the overall height of the antenna system (13m) is only around 25% the height of a 1/4 wave monopole (47m), with slightly better performance. However, the comparison is spurious because simpler medium-wave broadcast antennas than either of these are already in common use and do not require to be placed on a massive structure to work efficiently.
Read more about this topic: Crossed Field Antenna
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