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[N2TO]

Like Nike says, Just Do it!

I checked my POTA activations log and show exactly 1,000 QSOs CW & SSB running antenna since 22/09/14. The vast majority at 10 watts out with some at 20 watts out. Thirty-eight states and 19 countries worked. Hunters make it fun!

For 40M/20M multi-band I was thinking parallel elements and radials but linked elements & radials would be simpler. Thought to feed with ladder line to auto tuner too but that would be tough to route if tuner on dashboard.

GL

73 Kevin N2TO

[KD0VE]

Lots of great info here, many thanks for all the advice.  I have more than enough info to make a reasonably efficient set up.  Basic structure will be a hitch mounted 35' telescoping fiberglass mast that I've used successfully for an Inv L EFHW.  I'm thinking about 2 "anchors" with each supporting a guy wire and the elevated radial.   Guy wire length will be easily adjusted as the telescoping mast is adjusted.  Anchor is a weighted base pole about 8' tall.

Questions about the elevated radials; to make for easy changeover my thought is to have the radial in 3 segments joined by insulators.  A simple jumper bypasses the insulator when I need more radial.  This way once I'm set up the anchors wont have to be moved for a band change.  Any reason this is likely to be a problem?

AK5B "No, sloping the radials lowers the impedance---radiation angle stays the same." - thx for the correction.

[N2TO]

That is the question. I want to see if there will be any interaction between/among linked radials and linked element. I like inverted-vees and thinking the same for multi-band vertical.

73 Kevin N2TO

[WB6BYU]

...Questions about the elevated radials; to make for easy changeover my thought is to have the radial in 3 segments joined by insulators.  A simple jumper bypasses the insulator when I need more radial.  This way once I'm set up the anchors wont have to be moved for a band change.  Any reason this is likely to be a problem?...

No, it shouldn't be.  Or you can use parallel radials for each
band if you want to be able to change bands without fussing
with the antenna.

The problem with a linked radiator is taking down the wire
to reach the links.  Parallel elements, or a single radiator
used with a tuner, will make band changing easier.  But that
is a personal prefernence - any of those approaches should
still work well enough.

[NO9E]

Looks like suggestions are for a low SWR antenna that will stand 100 years!

For portable, the easiest choice is to use a vertical wire to a tree or to a telescopic  pole. One counterpoise. Feed with automatic tuner. The total length of the wire need to be > 3/8 wave for the longest band.   

If you have a Yaesu radio that supports the ATAS antenna, RT-100 can be controlled via the coax, without any control wires. Makes things much simpler.

[WB6BYU]

Looks like suggestions are for a low SWR antenna that will stand 100 years!

I thought we were discussing a wire hanging from a
telescoping fishing pole.

...The total length of the wire need to be > 3/8 wave for the longest band...   

Not if you want an effective radiation pattern on twice
that frequency or higher, like an antenna to work
10 / 15 / 20m.

A 3/4 wave vertical is a bit down from 5/8 wave, but
still generally usable without too much loss.  But as
it gets longer, more of the radiation is at high angles,
which aren't useful on 10m.  With a 1-wavelength
vertical on 10m (1/2 wave on 20m, which meets
your criteria for length) most of the radiation is at
higher angles that generally aren't going to support
ionospheric propagation.

Personally for my portable operations, I find it easier
to use a pre-tuned wire antenna that doesn't need a
tuner.  But partly that is because my QRP rigs
often don't have an internal tuner (or even an SWR
meter in some cases), and it is too much bother and
extra weight to bring one along.

But that's a matter of personal preference.