Thread: Antenna tuner
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Old April 9th 04, 04:44 PM
Dave Shrader
 
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Reg Edwards wrote:

Richard Clark,

I fully support your "All antennas have zero gain" campaign.


IMO applying the word 'Gain' to an antenna is misuse of the word 'gain'.

Beam forming antennas do concentrate the RF energy into an angle less
than 2*Pi steradians [Hemisphere] but the total energy concentrated is
still the power applied to the antenna minus losses. The far field from
a beam forming antenna is more intense than from an isotropic antenna.

Maybe the better term is to quote the solid angle at the 1/2 power
points in the E and H plane as a figure of merit. Example: antenna A has
a 1/2 power beam width of 2500 square degrees while antenna B has a 1/2
power beam width of 1800 square degrees.


Why not join the "There's no such thing as an SWR meter" campaign?
----
Reg, G4FGQ



Ah! But there are techniques for measuring TRUE VSWR!! [Not my little
Daiwa 101C or even the trusty Bird.]

Nope, I used to measure TRUE VSWR [in 1958] using a General Radio
Slotted Line with moveable probe!! I've forgotten the plotting details
but the answer came from plotting the response over 1/4 wavelength on a
SMITH Chart. Ain't cheap but it was accurate.

Seriously, I wonder if any readers recall the details of measuring and
plotting based on the GR Slotted Line?

Next question: where do I get a 160 meter 1/2 wavelength 50 ohm slotted
line?