Keywords
field-strength, E-field, H-field, probe, calibration
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Abstract
This paper complements White Paper 134 which was concerned
with the construction of a ‘pseudo TEM-cell’ for
DRM receiver testing. In essence, the pseudo TEM-cell comprised
a pair of leaky transmission lines within a screened room — one
close to the ceiling and the other close to the floor.
Between the two lines, the electric and magnetic fields
were both calculable and reasonably constant. Such an arrangement
would therefore be suitable for testing receiver sensitivity
under realistic conditions.
However, a receiver antenna
for use at 30 MHz or below is generally sensitive to
the electric field or magnetic
field, but not both. A receiver with a ‘magnetic’ antenna
is then more conveniently tested with a current-driven
loop, as described in British Standard 4054. Receivers
with ‘electric’ (telescopic) antennas are more
of a problem, as the electric equivalent of a loop does
not seem to be commercially available. The present report
therefore describes the theory and practice of such an ‘E-field
generator’. The conclusion is that an E-field generator is straightforward
to make and to calibrate. Used with care, it could prove
a useful adjunct to receiver testing where a pseudo TEM-cell
is not a practicable proposition.
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