Folded counterpoise?
 

I am about to make a multiband QRP counterpoise along the lines of the
one suggested in ARRL Low Power Communication at p. 6-2 -- which
employs a 50 ft length of flat 5-conductor cable.

Rather than use the 5-conductor rotator cable the author suggests, I
want to use ubiquitous 10-conductor computer rainbow ribbon cable, .05
pitch, zip construction, 28 AWG.

The author suggests a 50 ft length, which covers most bands from
10-80, with only the 80M counterpoise longer than 50 ft (it continues
-- connected tail to head -- onto the next conductor for 15.7 ft.)

Having five additional conductors on my ribbon cable than the author
had on his rotator cable, I want to add a few bands, 160M in
particular. This needs to run 131 ft, which is two full 50 ft passes
and one 31 ft length -- also to be connected tail to head, head to
tail, tail to head -- like a collapsed letter "Z" (or "N", for that
mater).

Does it matter if I put these right next to each other (i.e. 0.05"
away)? Or should I separate them with a non-resonant conductor? Or
what?

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

The simple answer is no. The wires must run more or less in a straight line
away from the base of the antenna. A little bending can be done, like an
"L", but you can't just zig-zag it back and forth in a 50 ft length.
--
Steve N, K,9;d, c. i My email has no u's.


"Ken" wrote in message
...
I am about to make a multiband QRP counterpoise along the lines of the
one suggested in ARRL Low Power Communication at p. 6-2 -- which
employs a 50 ft length of flat 5-conductor cable.

Rather than use the 5-conductor rotator cable the author suggests, I
want to use ubiquitous 10-conductor computer rainbow ribbon cable, .05
pitch, zip construction, 28 AWG.

The author suggests a 50 ft length, which covers most bands from
10-80, with only the 80M counterpoise longer than 50 ft (it continues
-- connected tail to head -- onto the next conductor for 15.7 ft.)

Having five additional conductors on my ribbon cable than the author
had on his rotator cable, I want to add a few bands, 160M in
particular. This needs to run 131 ft, which is two full 50 ft passes
and one 31 ft length -- also to be connected tail to head, head to
tail, tail to head -- like a collapsed letter "Z" (or "N", for that
mater).

Does it matter if I put these right next to each other (i.e. 0.05"
away)? Or should I separate them with a non-resonant conductor? Or
what?

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

On Mon, 2 Feb 2004 11:01:13 -0600, "Steve Nosko"
wrote:
The simple answer is no. The wires must run more or less in a straight line
away from the base of the antenna. A little bending can be done, like an
"L", but you can't just zig-zag it back and forth in a 50 ft length.

I found another posting that suggested that it is OK to fold the
counterpoise, as long as the folds are kept away from the antenna. Is
this true?

Assuming this is true, how far is far enough? It was anticipated that
the ribbon would run right up to the tuner. I could drop the 10M
conductor from the ribbon (using a separate radial for that) and put
the rest of the bands on ribbon cable that was 8.4 ft away. Or I
could put 10M, 12M, 17M and 20M on their own 4-conductor radial, 16.6
ft long, and start the ribbon cable for 30, 40/15, 80 and 160/60 at
the end of a 16.6 ft wire (which could even be a fifth conductor on
the high-band segment).

Ken KC2JDY



Ken
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remove "zz" from address)

On Mon, 02 Feb 2004 19:25:48 GMT, Ken wrote:

It was anticipated that
the ribbon would run right up to the tuner. I could drop the 10M
conductor from the ribbon (using a separate radial for that) and put
the rest of the bands on ribbon cable that was 8.4 ft away. Or I
could put 10M, 12M, 17M and 20M on their own 4-conductor radial, 16.6
ft long, and start the ribbon cable for 30, 40/15, 80 and 160/60 at
the end of a 16.6 ft wire (which could even be a fifth conductor on
the high-band segment).

Hi Ken,

Ultimately if you are going to use a tuner, what does it matter?

If the radials lie along the ground, what does it matter? The
proximity of ground is going to detune them anyway unless you get some
serious elevation (80/160M?) for the feedpoint. The proximity of
ground is going to kill the Q to the point of no serious tuning issue.
The proximity of ground is not going to be masked by onesy-twosy
radials. When you've already lost 6dB to ground, who's going to
notice another quarter dB lost to the tuner?

Run them zig-zag? What does it matter? Such conflicting advice is
obscured by results out two decimal places - your contact wouldn't be
able to resolve that difference on their S-Meter if they had a
binocular microscope focused on it.

73's
Richard Clark, KB7QHC

I think Ken is a little dramatic, but there's truth to what he says. If
you have a tuner, then it can (not will) cover a lot of sins. This depends
upon what you wind up with...all the stuff he mentioned.



I tuned my 40M inverted Vee on 75, at the transmitter end of about 100'
of RG58, and worked the east coast from Illinois with 100W SSB. Guys have
worked DX using a light bulb, gutters or a bed spring.



I will still hold that if you are planning (and I may have misunderstood)
to set this up so that: one "radial" runs out the cable, connects to
another wire in the cable, which then runs back up the cable near the base
of the antenna where it connects to another wire in the cable to go back out
the cable... this should be no better than the first run out the cable.

If, on the other hand, you are going to zig-zag one of the radials to a
moderate degree as it always is going further from the antenna, then this
has some merit in fitting the radials in a smaller space. However, if the
length occupied by the Zig-zagged radial is say, 50% the full length of the
radial, you won't have near the performance. I think the difference is
much more than two decimal places, but 2, 6 or even 9 dB is no big deal for
HF. It is a difference, but many poor antennas are usable. There is no
cliff of which you will fall off as you compromise the antenna



How much is "moderate"? What is "near the performance"? What if the
space it 75% the full length. yadda, yadda. This is a complex situation
and, unfortunately, there is no simple answer--- other than:: put something
up and see what happens.





General things which are changed by each other and the ground...

More radials is better.

It is "nice" to have radials 1/4 long, running straight away from the
antenna.

You can bend them - the more you do the lower the performance...probably,
but then how you gonna' tell...?

If you have longer radials, you may not need the shorter ones.

Radials have capacitance to ground changing some of the above.

The ground has loss and can change.



A vertical is sorta' like a dipole where one half it sticking straight up
in the air and the other half is "opened up" and spread out, around,
radially on the ground. This spreading-out changes things quite a bit, but
is a good starting point for a mental model. You can't take half of a
dipole and fold it up indiscriminately and still have the same performance.
As you start to do the folding, the performance will change bit by bit.
When the half is folded up to 1/3 its original length, it'll be very
different.


--
Steve N, K,9;d, c. i My email has no u's.


"Richard Clark" wrote in message
...
On Mon, 02 Feb 2004 19:25:48 GMT, Ken wrote:

It was anticipated that
the ribbon would run right up to the tuner. I could drop the 10M
conductor from the ribbon (using a separate radial for that) and put
the rest of the bands on ribbon cable that was 8.4 ft away. Or I
could put 10M, 12M, 17M and 20M on their own 4-conductor radial, 16.6
ft long, and start the ribbon cable for 30, 40/15, 80 and 160/60 at
the end of a 16.6 ft wire (which could even be a fifth conductor on
the high-band segment).

Hi Ken,

Ultimately if you are going to use a tuner, what does it matter?

If the radials lie along the ground, what does it matter? The
proximity of ground is going to detune them anyway unless you get some
serious elevation (80/160M?) for the feedpoint. The proximity of
ground is going to kill the Q to the point of no serious tuning issue.
The proximity of ground is not going to be masked by onesy-twosy
radials. When you've already lost 6dB to ground, who's going to
notice another quarter dB lost to the tuner?

Run them zig-zag? What does it matter? Such conflicting advice is
obscured by results out two decimal places - your contact wouldn't be
able to resolve that difference on their S-Meter if they had a
binocular microscope focused on it.

73's
Richard Clark, KB7QHC