Here are a couple of articles I found.

http://www.qsl.net/pa3hbb/arframe.htm
http://www.arrl.org/tis/info/pdf/0207040.pdf

The last link is for a 40 meter linear loaded dipole, but I think the
formulas should work.
GL es 73,
Terry, WK0F



"news" wrote in message .com...
Does anyone have a good source for calculating the length of linear loads
for a shortened 40 meter Vertical? I'm experimenting with a 20' vertical
and a pair of 10' parallel lines moved the resonant point near the 7 Mhz
band. Any suggestions?