Doesn`t work with a magloop!!!.....thanks anyway.

Why is that?

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Because there is only one phase - that which corresponds to the
motor
driving voltage.
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Reg.

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Automatic Antenna Tuners and Magloops.

All ATUs work on the principle of adjusting tuning components such
that the load presented to the transmitter has a reflection
coefficient of RC = 0+j0 ohms. When mismatched the RC has both
magnitude and phase.

So there must be two L and/or C variables. That's why there are always
at least two knobs on the front of a manual tuner. Or, when
automatic, two electric motors. Or a set of relays which accomplish
the same tasks.

In the case of a T-network the variable components are usually a pair
of reversible motor-driven capacitors.

There is always a reflexion coefficient bridge which is at balance
when the transmitter load is simultaneously R = 50 and jX = 0. Or
impedance Magnitude = 50 and Phase = zero.

The RC bridge circuit is similar to the so-called SWR bridge except
that there are TWO voltage outputs - proportional to magnitude and
phase of the RC. Output voltages are amplified to drive the
reversible capacitor motors or operate the set of relays. The motors
go backwards and forwards and react with each other similar to what a
human operator does. When Z Magnitude = 50 and Phase Angle = zero, or
sufficiently near, motors stop and the green LED comes on.

Now, in the case of a magloop there is only one variable - the tuning
capacitor. The other component involved with the tune-up process is
FIXED. It is the diameter of the small coupling loop inside the main
loop which is fixed.

The small coupling loop, in conjunction with the main loop, behaves as
the single-turn primary winding of an impedance matching transformer.

The main loop, when at resonance, has a very low purely resistive
impedance, the sum of the radiation and loss resistances.

The effective turns-ratio of the transformer is approximately
proportional to the ratio of the areas enclosed by the two loops. It
so happens that when the diameter of the coupling loop is approx 1/5th
of the main loop diameter, the impedance looking into the coupling
loop is 50 ohms. If a 75-ohm feedline is used then the coupling loop
needs to be a little larger.

A nice property of a magloop is that an impedance match is
approximately independent of frequency. When changing bands it is not
necessary to change the diameter of the coupling loop even if could
easily be adjusted.

It can now be seen why the conventional ATU cannot be used with
magloops. What is needed is something which searches for minimum loop
impedance, or zero phase angle, as the tuning capacitor is varied. It
then stops.

Any ideas?
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Reg, G4FGQ