"RB" wrote
Longwire antenna. Coil in parallel with var cap for matching circuit.

What is the likely Z range such a circuit might match?

-------------------------------------------------

To put you in a good-enough ball-park, the input impedance of a vertical
wire, or an inverted-L antenna, is R + jX, where -

R = Square( 24 * L / Lambda ) ohms.

X = - 550 / Tangent( Angle ) ohms,

and where

L = overall length of the wire in metres.

Lambda = free-space wavelength in metres.

Angle = 2 * Pi * L / Lambda, in radians.

Or alternatively,

Angle = 360 * L / Lambda, in degrees.

For a thick lattice mast, change 550 to 350.

If you know what it is, add the ground electrode resistance to R. Otherwise
make a guess.

The foregoing good-enough approximations apply to overall wire lengths or
heights of 3/8 wavelengths or shorter.

Note that when L / Lambda passes through 1/4-wavelength, the reactance X
passes through zero and changes from negative (capacitative) to positive
(inductive). And R passes through 36 ohms as is common knowledge.

About the only practical use of the above pair of equations is if you intend
to follow by designing your own tuner, coil and capacitor values. Or
checking that a commercial tuner has an adequate range of operation. For
this a small computer program is needed unless you have hours to spend on
doing the unavoidable calculations.

But the real value of such simple equations lies in their ability to
precisely and very succinctly describe how antennas WORK. Far, far better
than thousands of vague words, spread over years, from agumentative,
disruptive, albeit well-intentioned do-gooders.
----
Reg, G4FGQ