If you cannot convince yourself to put in the pile of ground radials,
you can use an ELEVATED 40 meter vertical. You can SHUNT FEED it so
that it does not require an insulator, making the whole affair solid
grounded to boot. Your radials should be a minimum of 9 feet up off the
ground. You may make the shunt section out of six inch TV twin lead
stand off mast clamp spacers, and use not much of a spacing for the
trimmer capacitor for the gamma match that feeds it. You will find that
you can take about a three foot section of RG-8 coax, and turn it into a
capacitor by connecting the shield to one side of the coax feed line and
the center conductor to the gamma match wire section which you make out
of ordinary copper wire or whatever.


Put a couple turns of hard copper ac wire around a screwdriver handle.
Put that across a common antenna insulator as a two turn coil. Connect
that in series with an elevated radial. Stick a grid-dip oscillator in
the middle of that little loop and tune the radials to reasonance by
shortening them from too long to your target frequency. Adjust the
length and the gamma match deal with an AEA or other antenna analysis
unit for flat SWR at the coax feet terminal for your project.


Using the totally grounded method described lets you go down to the base
of the pole and make SURE that it goes to a good ground rod. Use a few
short six or eight foot radials at ground level to create the drain for
any direct lightning hit you may take. The idea works very well from
experience and more than one hit.


Run your coax feed line for the affair to the base as well and thence
into the shack, using techniques that ground it well too, plus proper
interface lightning suppression where the coax comes into the shack as
well.


Here in the W5 call area, with a KW against it and a good receiver, on
CW in either the CQ-WW or the ARRL CW DX test, I've consistently been
able to pile up between 80 and 100 countries in any given contest ..
often as many as 400-500 plus 40 meter QSO's. By using flag pole
techniques you can make it look as neat as a pin for the inquisition ..
grin.


If you have noise problems, you can help that with the new cancellation
RF devices. As well, you can also design the thing so that you can
cover 80 meters too!


The way to do that is to create the main vertical element so that it
also has a folded loop operation all the way up to the top and down. On
80 you feed it is a folded monopole. On 40 you short that folded
monopole at the base ,, a presto you have you full length 40 meter
element with a wider element profile, that is all.


Proper use of a Rohn 25-G few sections and a concrete ufer style base
can get you a completely self-supporting element for the basic
contruction. The neat part of this is that you can go inside that tower
and run additional coax up it to get a small VHF antenna or dish up
there. Or you can also side straddle mount a little Wireless 802.11
paddle or dish up there and PRESTO, if there is an IP wireless service,
you can run that or whatever through, say, CAT-5 inside the tower .. and
instant high speed connection for you as well. Just bring the internal
lines down the inside of the tower and do the lightning mitigation work
at the base for them as well.


Yes, you'll have to adjust the tower height to account for the effect of
whatever other metal mass is up there for stunts like this, but you
*CAN* do it and do very well on 40 and 80 too! Plus if you get bold.
you can get a full sized 80 meter stick up there with Rohn 25-G and a
galvanized mast stinger on top which works just as good on 80. But
you'll have to use guy wires and so on for the elevated version, which
of course has those longer elevated radials as well.


It's neat as a pin, terribly structurally efficient, and works a heck of
a lot better than any horizontal affair you are likely to get up in your
restricted space.


W5WQN ..


Mark Sheffield wrote:

With the downturn in the solar cycle and worse days ahead, I'm faced
with operating on the lower hf bands. 20M has gotten to be very hit
or miss wrt propagation and it seems that more and more dx is
happening on 40 (with some on 30). I have a 40M dipole up about 30 ft
or so, but that really doesn't cut it.

I know that this is like a discussion about "what's the best color",
but what antenna systems will work well on 40M, maybe even 80M, that I
could mount either on the ground or up no higher than 30 ft? I need
to at least get some general direction on this from an experiential
data set rather than starting with the ads in QST or CQ.

Tnx - Mark Sheffield/N0LF



--


-- Sleep well; OS2's still awake!

Mike Luther