"Ken Bessler" wrote in message
news:Tpzhd.40784$lp6.34766@okepread01...
The ARRL antenna book describes the inductive effect
of traps on lower freqs and how this physically shortens
the antenna. They talk about L/C ratio and give two
examples.

Problem is they don't give the formula! #$%#%$!

Here's my antenna - it's a 75/160 trap dipole. The traps
were designed with W8VVM's software. Cutting the
75m portion of the antenna is easy - I need to know how
long (as a starting point) to cut the 160 m end pieces!
[...snip...] Trap data un needed.

Summarizing the other two posts and what you alredy know. With the effects
of the surroundings the formulas won't be much good anyway.

Put the traps at the ends of the standard 75M dipole [["75m portion ...is
easy ..."]]. Make this a little long if U like. Add a little too much wire
for the 160, then measure the 75M and 160M min SWR freq. Adjust the 75M
length for your 75M freq of interest. Then, using 468/F figure out how far
off you appear to be on the 160 length. Trim off about 80% of that value,
then trim-by-SWR the rest of the way.

Sound good fellas?

[[personally, i think if ur 2:1 makes no diff at the other end]]]
--
Steve N, K,9;d, c. i My email has no u's.