Well, as someone else said, theory asside, I've put up an antenna in one 
place and it worked great, put it up some place else and it wasn't good at 
all.  I had a g5rv up here in Vegas as I only have a 100 foot lot and it 
wasn't all that great.  I also wanted something my solid state amp could 
work with as I don't have an external tuner.  I bought the b and w 1.8-30 
which is a folded dipole looking thing.  I clal it my dummy load with 
wires.  It is fed with coax, has a balon at the bottom and an unknown 
plastic thing, I think a resister in the center of the top wire right 
above the feed point.  It covers from 1.8 to 30, although it doesn't work 
well at all on 160.  I've compared it to a gap vertical that I have up 
here and some times one is better and some times the other is.  I am not 
exactly sure, but think the over all length is 105 feet.  The wires are 
about 18 inches or so apart with spreaders of corse.
It is a compromise antenna, but seems to work fairly well here and works 
on all bands.
73s
Butch Bussen
wa0vjr