Dear LF group
Does anyone have an idea how to design an electronic goniometer?
Imagine a "black box" that is fed with two signals from a pair of orthogonal
(for example N/S and E/W) untuned loop antennas, let's call them X and Y.
The output from the box should ideally be X * cos(A) + Y * sin(A) where A
is a control signal which could be a simple DC voltage, a digital control word
or whatever.. Such a "black box" could be very useful for direction finding
without the need to rotate a loop physically.
When combined with an omnidirectional antenna and a phasing circuit, the
resulting cardioid pattern can also be used to null out interference, just like
a K9AY antenna does, but better - with steerable, instead of fixed, null
directions. My two loop / eight nulls (modified) K9AY is doing a nice job
but I miss the ability to put the null in ANY direction...
The "black box" could be a pair of attenuators with ability to switch the phase
180 deg's. In its simplest form it could be just two potentiometers and two
switches (and phase reversal transformers). This would be OK to manually
null out interference but to make accurate D.F. measurements, precise
sin/cos behaviour of the attenuators is required.
Any ideas? (besides making a "physical" goniometer)
73 de Johan SM6LKM
|
