Topband: 160 Antenna Struggles

[DAVID CUTHBERT]

Rip,

welcome to Topband. I ran an EZNEC model of your antenna. Sloping the top
wire downward and the radials upward as you have reduces the effective
vertical length thereby reducing the radiation resistance. The radiation
resistance of the antenna is 4 ohms whereas if the top wire was horizontal
and the radials were horizontal the radiation resistance would be 12 ohms.

The 1.6:1 VSWR tells us the feedpoint resistance is either 30 ohms or 80
ohms. It is probably 30 ohms and that tells us the GND loss resistance is 26
ohms, the radiation resistance is 4 ohms and the radiation efficiency is
13%. You are radiating 13 watts of 100. Running the wires horizontal to
obtain a 12 ohm radiation resistance will increase the radiation resistance
to 32%, all other things being equal.

Running the same transmitter power at both ends of the RF link will produce
the same signal at the receivers. If the other station is S7 at your RX you
are S7 at his RX. On topband signals are often near the noise level. You
might hear a KW station 6 dB above the noise and copy him just fine. In this
case your 100 W is 4 dB below the noise (same noise level at both ends) and
you are ignored.

A bit of antenna work and an amplifier - even a 500 watt Ameritron AL811 is
a formula for topband DXing success.

    Dave WX7G