40M HF antenna suggestions
 

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

Hi

One possible could be ground mounted vertical array.
There are triangle and quad (four "corner" ) constructions.
Triangle gives 6 switchable directions and some gain and FB but
requires radial wires to be effective.

QST Aug -72 had a quite extensive article of 7MHz triangle array.

73 Kari B


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

If you have the horizontal room (70 feet, sounds like you might) and
at least 35 feet up, why not a Half Square for 40? Doesn't need
radials, it's an 'upside down' phased vertical array with some gain
and a good TOA. Be aware however, it is somewhat directional. Easy to
make on your own, also cheap and there is a lot of info on the Web.
I have one for 20 meters (very modest with the antennas here) and it
works a lot better than my R5 vertical and full sized G5RV.

A horizontal Loop at low elevation can be an effective low angle radiator
when it is more than 2 wavelengths around.

I had a loop running around trees in my yard, irregular shape and random
length (210 feet), fed it with 300 ohm tv line. It worked quite well. At
its highest point it was under 30 feet and it was at 20 feet on two corners.
I even loaded it up on 160 and worked both coasts from here in Chicago with
100 watts.

Read up on the topic at
http://www.cebik.com/atl1.html

He has lots of other interesting antenna articles on that site, just stop
the address at the com/ to see the list.

KA9CAR
John


"Mark Sheffield" wrote in message
...
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

Mark,

You're not going to like my suggestion but here goes...try a vertical. Ask
around, the people with the poor ground systems and those that have never used
one will condemn them. Those that have used them with good ground systems will
praise them.

73s,

Evan

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

Thanks for all the replies and suggestions, both to the group here and
via email. Just about all the suggestions have been to go vertical in
on manner or another, and this I will do.

Thank you all - Mark Sheffield/N0LF

Very good advice, Irv

Irv Finkleman wrote:

If you plan to be at your QTH for a while, it's not difficult to
lay untuned radials along the ground, or bury them down a half inch
or so with a pizza cutter. I laid mine in the grass and after a
couple of months you don't even see them anymore -- the mower goes
right over them. If you are concerned, you can nail them down
using hairpins. They not only serve as a great base for a vertical,
but they also provide a very good rf ground. They don't have to be
any special length -- its the quantity that counts.



--


-- Sleep well; OS2's still awake! ;)

Mike Luther

Irv & Mike - the radials don't have to be tuned? Or - the real
quesion - they aren't random length, you're still talking about
cutting a bunch for 80M, a bunch for 40M and a bunch for 20M (or
something like that) and then fanning out all the radials from the
base, correct?

Question - if and when I put up a vertical, how close can it be to a
tree, the house, etc, if ground-mounted?

tnx - Mark


On Thu, 28 Aug 2003 16:29:22 +0000, Mike Luther
wrote:

Very good advice, Irv

Irv Finkleman wrote:

If you plan to be at your QTH for a while, it's not difficult to
lay untuned radials along the ground, or bury them down a half inch
or so with a pizza cutter. I laid mine in the grass and after a
couple of months you don't even see them anymore -- the mower goes
right over them. If you are concerned, you can nail them down
using hairpins. They not only serve as a great base for a vertical,
but they also provide a very good rf ground. They don't have to be
any special length -- its the quantity that counts.

Mark Sheffield wrote:

Irv & Mike - the radials don't have to be tuned? Or - the real
quesion - they aren't random length, you're still talking about
cutting a bunch for 80M, a bunch for 40M and a bunch for 20M (or
something like that) and then fanning out all the radials from the
base, correct?

Question - if and when I put up a vertical, how close can it be to a
tree, the house, etc, if ground-mounted?

tnx - Mark

On Thu, 28 Aug 2003 16:29:22 +0000, Mike Luther
wrote:

Very good advice, Irv

Irv Finkleman wrote:

If you plan to be at your QTH for a while, it's not difficult to
lay untuned radials along the ground, or bury them down a half inch
or so with a pizza cutter. I laid mine in the grass and after a
couple of months you don't even see them anymore -- the mower goes
right over them. If you are concerned, you can nail them down
using hairpins. They not only serve as a great base for a vertical,
but they also provide a very good rf ground. They don't have to be
any special length -- its the quantity that counts.



If you are going to tune radials, they have to be above ground
level by a distance that makes setting up a vertical a much more
complex matter. The idea of tuned radials allows you to operate with
as few as three and provide an effective rf balance for the antenna.
The main idea of the radials, tuned or untuned is an rf ground to
act as the phantom half of the vertical. They need not be tuned, but
if you lay them on or below the ground you need more of them. On the
ground, what would have been a tuned radial, interacts with the soil and
detunes, so the length becomes unimportant. You provide the ground by
using more radials of various lengths, and they need not be spread out
as 'radially' as the pictures show -- but the more the merrier, and the
more effective they will be.

One of my verticals was four feet from the house. I fired an arrow
into the air, so to speak, but my arrows (signals) landed into a lot
of very interesting places (other stations).

Some lucky guys have their verticals mounted right at a tree and use
it for the vertical support.

Hope this is clearer than mud :-)

Irv
--
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Beating it with diet and exercise!
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58"/43"(!)/44" (already lower too!)
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada