At 1.6 MHz at 4 foot long helical would be very low impedance - probably
around 1 ohm or so at resonance. You would have to feed it against ground -
ground losses would be 30-50 ohms, depending on your grounding mechanism. So
the antenna might be a good match but radiation efficiency would be only 1-2
% as most of the power will be lost in ground resistance.

Richard

matt wilson wrote in message
...
Any tall light-poles nearby? You could put a tap onto one a couple of feet
up from the base if you have an antenna tuner.
100mW in for 60mW out? Doesn't sound like much of an amplifier!

"gudmundur" wrote in message
...
I do sound work at horse shows, and would like to provide my audio
source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in
length
and having the 3/8 24 thread at the bottom so I can fasten it into my
hamstick
mag mount base.

I am thinking a 1 inch diameter wooden dowel 4 feet long, and wrapped
evenly
from bottom to top with perhaps #22 wire.

Any idea how much wire it would take to begin to act like a 50 ohm
impedance
at the base? Would you solenoid wind it bottom to top, or would it work
better
with maybe a 4 inch high multilayered coil at the bottom and 3.5 foot
steel
whip antenna.

I am not out to **** off the FCC, and with a mere 60 milliwatts of
output
power at 50 ohms, I don't think anyone beyond 300 yards will even here
it.
I do however want to be clearly heard on an A.M. car radio anywhere on
the
show grounds. There are no local stations on 1600khz, or even anywhere
near
it, and since these shows are only in the daytime, I won't be competing
with
skywave, or 50kw clear channels.