I have a few comments to make: There is
no provision to amplitude balance the antennas or to compensate for minor
delay-line loss. One is therefore assuming that the antennas are
always?gain matched with frequency even when the presence of nearby objects
could be affecting the gain. This will?in some circumstances reduce the F/B
as nearby objects (metal fences, power/phone line etc) affect the antennas
near-field response especially at LF/MF.
?
My experience with MW active dipole,
active loop and active K9AY arrays using variable delay-line and switched
delay-line phasing indicate that the provision to vary the antennas gain is just
as important as having control over the phasing.
?
I agree with your observation that a 1
to 10? frequency ratio is readily
achievable. However, where the antenna spacing is very small, there is a further
degrading in s/n due the amplifier noise not cancelling out in same way as the
signal. This is more of an issue with small 1m diameter high gain loop antennas.
Also with very close antenna spacing the array phasing and gain balance becomes
very critical, causing pattern degradation. Therefore, it may be prudent for
MW/LW use to allow for an increase in antenna spacing to over
30m.
?
Using the above arrays at HF can be
quite disappointing due to signals having too much angular variance. Loop arrays
offer the worst performance because they offer little rejection of rear high
angle signals.
?
Additional
Reference:
?
Keen¡¯s Wireless direction Finding, Third
Edition 1938.
