impedance of a wire antenna, knowing it's length and height above ground?
Z is in ohms
H is the height of the wire above ground in feet.
D is the diameter of the wire in inches
The length of the wire does not matter.
This is Z is the result of electric field effects measured relative from
You can see by formula that the higher the wire is the higher the
impedance and the larger the wire size the lower the impedance will be
for the wire.
A typical wire will represent hundreds of ohms. An 18 guage wire would
be ~ 500 to ~ 600 ohms 5 to 15 feet above ground.
A good source for these formulas is the ARRL antenna book. The ARRLQuote:> Anyone here know of a formula or other manner in which to determine
> impedance of a wire antenna, knowing it's length and height above
Here's a couple of radio amateur sites:
Look for the "Practical Antenna Notes"
Reg Edwards has written some computer programs which greatly simplify
using some of the more complicated formulas. There are a few of them
But the effects of the antenna's impedance are far more important when
transmitting. As a practical matter, receivers work fine over a broad
range of impedances.