I saw both these articles but they are still both fairly weak on theory.

K4VX's article was what inspired me to try using a ladder line. He
apparently tried several lengths in NEC and then built an antenna from that
result. I've done that as well and it gives you a good start but doesn't
expose the theory of calculating the loads.

Reid's article starts with a very simple model. He makes the load length
equal to the "missing" length of the radiator! Then he complicates the
analysis with a top hat which he uses to create an "adjustment". That
apparently got close and then he pruned till he got resonance in the range
he wanted. It wasn't clear how the size of the top hat relates to the
length of the load.

The ARRL Antenna book has great analysis of the calculation for top hats but
no similar analysis for linear loads - at least I didn't find any.

Any help appreciated



"Terry Ashland" wrote in message
om...
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?