Robert Smts wrote:

Use the longest 2 X 4s or 2 X 6s you can find, and make an an A frame out of
them, with the bottom 2 to 3 ft wide. Bolt them to some stakes driven into
the ground next to the fence, and then stand up the A frame against the
fence. With luck, you should be able to get 20 ft or more, even if you need
to bolt a couple of 2 X 4s together to lengthen them.

Otherwise, you could do the same thing with an aluminum house ladder that
goes up to 30 or 40 ft, and use it to tie the antenna to.

Bob, VE7HS

Just a week ago I took down a 40 foot high 2 X 4 wood (untreated Douglas
fir) A-frame I've had up for about 30 years. It hasn't had any
maintenance except for a couple of coats of deck stain. It finally
developed enough rot at points where it was nailed and bolted that it
had to come down. The A-frame was built according to the design which
has been in the ARRL Antenna Book for decades. It's still there -- look
for "A-frame mast" in the index. I once made a slightly shorter one with
2 X 3 lumber. It was a lot lighter and easier to handle, and plenty
strong. Even 2 X 2s would be ok for moderate height, if you can find
some reasonably clear pieces. If you're going to be supporting it with
something like a fence, you'll need to keep the weight to quite a bit
less than my 40 foot 2 X 4 version. Lower height, smaller dimension
lumber, a lighter type of wood, or some combination should get you
something usable.

Roy Lewallen, W7EL