Jim Miller wrote:

OK, at cecil's suggestion I changed to a single 20 segment wire with a
split I source at 50%. I ran the SWR plot against a 300ohm alternate
impedence. Is that the way to see what effect a 300ohm twinlead will
have? Now I get a minimum 2:1 SWR at 5.6Mhz and a pretty smooth convex
curve out from there to 14.5Mhz with a max SWR along that leg of around
35 at 12.1Mhz.

That's more like it and you don't need a split-I source in the
middle of one wire. Split-I sources are used at the intersection
of two wires. 492/88' = 5.6 MHz. 984/88' = 11.2 MHz.

For 7 MHz and up, this antenna would be better behaved with 450
ohm ladder-line or open wire line. The best Z0 for the feedline
is Sqrt(Rmin*Rmax) ~ Sqrt(50*7000) ~ 600 ohms.
--
73, Cecil http://www.qsl.net/w5dxp

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