mike wrote:
My 30 yard long random wire goes from the gutter @ 25 feet high down
to a wooden post at the end of the yard. From there it goes another 20
yards at an average of 3 feet high. Works great compared to the whip.
Fed with coax, I dont get household noise at all.

While this setup works, gain is minimal. If all 30 yards were 9 feet
high or better then I might get up to 6 db of gain.

Gain in a horizontal antenna is always associated with directivity. In
order to have gain in some directions, you must have nulls in other
directions. Unless the gain is in the direction of your target, it
will do no good. Also, the directional pattern will be vary
significantly with frequency.

A good rule of thumb for a DX antenna (for good low-angle reception)
is to install a horizontal antenna at least 1/2 wavelength above
ground. At 15 MHz, that's about 33 feet. At 5 MHz, it's about 100
feet.

You'll still hear plenty of signals with a mediocre antenna. A more
efficient antenna will pick up more signal, but also more noise.
However, a DIRECTIONAL antenna aimed in the desired direction WILL
improve signal-to-noise ratio. That's because it will reject noise and
other signals coming from other directions.

Art N2AH