"Jeff Liebermann" wrote in message
...

snip

... However, what I was hoping for was some manner of
fairly short antenna (about 3-6 meters), with a fixed LC network that
yields a fair approximation of 50 ohms. 2-30MHz, without tuning. I've
been playing with such a matching network in 4NEC2, but getting
nowhere. Surely, such a thing exists.

I can address that but, alas, not with encouragement.

When I was working, my domain included Navy shipboard antennas, including
broadbanded HF transmit antennas, fed by banks of four or eight couplers
through 50-ohm Heliax. (Yes, I know your application is receive-only.
Please stick around.)

When a ship had the usual three antennas, they covered the range of 2-6,
4-12 and 10-30. At each one's feed point, a fixed, passive matching network
using two, three or four reactive components brought the antenna inside the
3:1 circle on a Smith chart. (We didn't adjust them, we just periodically
inspected and tested them. Why, Ye-es-s-s, we usually found loose, missing
or corroded hardware on the mast. Why do you think we climbed up there?)

I mention this because the Navy tried to get better by doing HF transmit
using only two broadbanded antennas (2-9 and 8-30) but had to relax the spec
to a 4:1 SWR. It worked on a few ships, but the radiomen often encountered
freqs that were difficult or impossible to tune, so they'd revert to a whip
antenna with a base coupler, like the Harris RF-601.

A good passive matching network for 2-30 seems unlikely. The Navy would
have bought them by now if "surely such a thing exists."

"Sal"