Hi,

I'd like some advice for determining the best antenna to put up in my
situation.

I am getting set to move to a trailer park in northeast arizona, about
50 miles west of Gallup, NM. Locals have no objection to antennas so
long as people don't have to run into them via normal passage ways.
The trailer is 12 feet high by 15 feet wide by 50 feet long, facing
N-S. Nearest certain ground is electrical panel. The water pipe is
metal but could be interrupted throughout system by PVC. There may
also be significant noise from AC systems in park.

Good news is that my wife is giving me an entire walk-in closet for my
station, and that I can lay aluminum foil against all surfaces to
create a Faraday cage.

I have approx 25 to 30 feet between my trailer and neighbors, and a 35
foot altitude streetlamp 6 feet away curb. Soil conductivity is red
clay, extremely poor. Significant rainfall (monsoons) summer to fall.
Winds gusting to 50 or 60 mph during winter. Soil frosts between
October to March.

I would like to work CW DX on 40, 30, 20, and 17 meters. 80 and 160
would
be a bonus. Conventional options such as tower or surplus telephone
pole are out of the question due to cost and lack of available area.
Radials must be buried as children are playing nearby.

Probable options:

1) Load up the streetlamp with an antenna matcher, work against 180
degrees of buried radials out to 1/8 lambda.

2) Solder a series of tin/steel cans (cantenna) using pocket torch and
copper tape to 1/4 lambda with added capacitance hat(s), brace the cans
against the ground and the trailer, work against 270 to 360 degrees of
buried radials out to 3/8 lambda.

3) Create a mast from 40 feet of metal pipe and 15 feet of wood rod,
brace against trailer burying pipe end 10 feet, mount an inverted vee
trap dipole in N-S direction for E-W DX.

4) Pair of masts on either side of the trailer, mount a delta loop
from each mast, feed one loop and use the other as a reflector.

5) Pair of cantennas on each side of the trailer, operating as out of
phase pair of 1/4 lambda verticals.

Which would be best? And where do I place the lightning arrestor(s)?

Thanks,

The Eternal Squire

On 11 Sep 2005 23:07:39 -0700, wrote:

I would like to work CW DX on 40, 30, 20, and 17 meters.

Hi OM,

Not 10, 12, 15, nor 60?

80 and 160 would be a bonus.

They would be a miracle - sometimes miracles are indistinguishable
from luck or accepting comes-what-may.

Probable options:

1) Load up the streetlamp with an antenna matcher, work against 180
degrees of buried radials out to 1/8 lambda.

How would the park owner feel about that? 1/8 lambda of what? 80M?

2) Solder a series of tin/steel cans (cantenna) using pocket torch and
copper tape to 1/4 lambda with added capacitance hat(s), brace the cans
against the ground and the trailer, work against 270 to 360 degrees of
buried radials out to 3/8 lambda.

Sure, it's been done, but more as a gag because so many simpler
options are available. It will need just as much guying as the next,
more conventional vertical anything. So why not just go out and get
that some nested tubular sections? Army surplus field antennas 40
feet high have been selling for $80 - $100 for years. And they come
complete with even the sledge hammer to sink the guy pegs.

3) Create a mast from 40 feet of metal pipe and 15 feet of wood rod,
brace against trailer burying pipe end 10 feet, mount an inverted vee
trap dipole in N-S direction for E-W DX.

Ah! 40 feet of metal pipe. Glad to see that the stack of cans has
an alternative. Well, this is a start for testing various designs
against.

4) Pair of masts on either side of the trailer, mount a delta loop
from each mast, feed one loop and use the other as a reflector.

An elaboration of the 40 feet of metal pipe.

5) Pair of cantennas on each side of the trailer, operating as out of
phase pair of 1/4 lambda verticals.

Dump the cans and stick with the 40 feet of metal pipe. But it seems
we got here by wanting an antenna that worked most the bands. The
"phase pair" is not that and it will probably have more effort
involved than perceived return. Certainly that is something that
never stopped anyone who starts this kind of project and it will offer
hours of diversion.

Which would be best?

The one with best DX. You could as easily ask which would be:
the easiest, efficient, practical, useful;
or to go with the antonyms:
the absurdest, illogical, impractical, tortured....

It all depends on wavelength and the terms flip from one category to
the next, appropriately.

Overall, the longest dipole you support as high as possible, with a
twin line transmission line to a tuner. Add a ground field so you can
tie the transmission line together to drive it against the ground for
the lowest band.

And where do I place the lightning arrestor(s)?

As close to your ground field as possible (with it, in turn, tied to
the ground of your panel per code) or you will become the Eternal
Flame.

73's
Richard Clark, KB7QHC

Eternal Squire wrote:
"I`d like some advice for determining the best antenna to put up in my
situation.

I am getting set to move to a trailer park in northeast Arizona."

Phil Rand, W1DBM distilled 35 years of trailering experience in QST and
it was reprinted in the 1978 ARRL Antenna Anthology.

As Richard Clark wrote, there is no miracle antenna.

Phil found a simple dipole only a few feet above ground would outperform
a mobile whip on 40 or 75 meters.

Here is Phil`s Table 3:

Hustler 75-meter Mobile whip mounted vertically on top rear corner of
trailer-------S7

Same as above with 60-foot counterpoise connected to
trailer-----------------------------S9

Two Hustler mobile whips back to nack
as a horizontal loaded dipole-------------S9+5dB

60-foot horizontal wire 8 feet high using trailer (30-ft. Airstream)
as ground------S9+10dB

Hustler 4BTV trap vertical with
75 meter resonator-------------------------S9+10dB
120 foot dipole, 15 feet high at
center------------------------------------------S9+20dB

Airstream Loop antenna------------------S9+20dB

Home station dipole 50 feet high------S9+30dB

Feet = 0.3048 m

There is a lot more in the article which may interest operators from
trailers, but I`m not a typist. Check the Airstream Loop antenna.
Nothing extends laterally from the trailer to trip anyone up.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Phil found a simple dipole only a few feet above ground would
outperform a mobile whip on 40 or 75 meters.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Without more information, this comparison is flawed. A mobile whip has
a lower angle of radiation than a horizontal dipole. On 40 or 75, the
vertical component of radiation can be quite significant for close-in
stations (100 miles or so). At night, working long distances, the whip
may outperform the dipole. During the day, the dipole will probably
outperform the whip.

It all depends.

73, Bill W6WRT

Phil found a simple dipole only a few feet above ground would
outperform
a mobile whip on 40 or 75 meters.

NVIS sure...Wouldn't be so sure about long haul... My 40 meter
mobile beats my home dipole at 40 ft on a 1000 mile path.

Here is Phil`s Table 3:

Hustler 75-meter Mobile whip mounted vertically on top rear corner of
trailer-------S7

Part of the problem...His mobile is stunted...

Same as above with 60-foot counterpoise connected to
trailer-----------------------------S9

Two Hustler mobile whips back to nack
as a horizontal loaded dipole-------------S9+5dB

Again kinda stunted due to the lousy hustler coils...
Could be better than that if better coils were used.

60-foot horizontal wire 8 feet high using trailer (30-ft.
Airstream)
as ground------S9+10dB

Pretty mediocre if NVIS...

Hustler 4BTV trap vertical with
75 meter resonator-------------------------S9+10dB
120 foot dipole, 15 feet high at
center------------------------------------------S9+20dB

Airstream Loop antenna------------------S9+20dB

Home station dipole 50 feet high------S9+30dB

Sounds like these are all NVIS paths... For those,
I agree, a dipole/loop is usually best. One problem though...
Often when mounting a low dipole next to a large metal trailer, etc,
the coupling often will make tuning quite difficult. I'd try to get
the dipole as far away from the trailer as possible *if* it
acts squirrely... But a *good* mobile antenna could often
be quite good to longer hauls. On the higher bands, a good
mobile antenna should be just fine.
If it were me, I'd #1 run the best mobile antenna I could rig up
as a vertical. Then I'd run a dipole for low band NVIS stuff. In my
case, I prefer paralleled multiband dipoles, at right angles, but
if I can only run one wire, I'll make a multiband dipole split
up with clipable insulators. If thats not workable, I suppose a
trap dipole could be used, but thats always my last choice
for a multiband dipole setup, being I like every drop of
efficiency I can muster. But the losses with those is not that bad.
With my mobile antenna, I could easily use *just it* if I wanted,
on any band. But my mobile ain't no stunted hustler antenna.
When I'm parked, my usual coil position is higher than the total height
of the average hustler whip. My mobile eats hustlers for lunch
and spits out the seeds... It's ugly. I did some tests using
hustler coils
vs my usual homebrew...Wasn't pretty... Adding the hustler coil
is like turning the antenna into a dummy load, *even* considering
that in most mobile setups, ground loss overshadows coil loss.
So if you see a *drastic* decrease in perfomance when changing
coils, Houston, we have a problem. I've seen many claim the "small"
hustler coils are actually more efficient than the "super" coils, which

was the type I tried. Luckily , I didn't pay for it, and I gladly gave
it back after testing... I think he stuck it on a hustler vertical...
Poor
thing.... I'd forget the "can" antennas, etc...A good mobile whip
would
likely do about as well. I'd use wire, or regular masts to make a tall
vertical. To me, cans sound like a soldering nightmare... :/ MK

Bill Turner wrote:
"Without more information, this comparison is flawed."

I agree the information was incomplete. I dfid not reproduce the whole
article. The fault was mine, not Phil`s. A low dipole has a high
radiation angle. For comparison, Phil was working Airstream net stations
in New York, New Jersey, Maryland, Pennsylvania, Ohio, and New England.
Phil was located in Ontario near Buffalo, New York when he collected his
data. His in-laws lived there. Phil`s home QTH at the time was the
highest spot in Western Connecticut, with a line-of-sight path to New
York City. Phil had surrounded his mountain top with rhombic antennas
pointed toward his likely targets. Amateurs answered when he called.

In the Airstream net, most of the contacts were made Sundays on 3963 kHz
at 8 am local time. Sky wave was mostly near vertical incidence. The low
dipole was good for the job. Not too directional and a lot of radiation
nearly straight up. Phil noted that several times when he switched to
to the mobile whip, he could not be heard through the QRM.

The numbers Phil put in Table 3 are only true under the conditions
prevailing when he made the checks.

Best regards, Richard Harrison, KB5WZI

On 13 Sep 2005 16:15:08 GMT, "Bill Turner" wrote:

Richard Harrison wrote:

Phil found a simple dipole only a few feet above ground would
outperform a mobile whip on 40 or 75 meters.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~

Without more information, this comparison is flawed. A mobile whip has
a lower angle of radiation than a horizontal dipole. On 40 or 75, the
vertical component of radiation can be quite significant for close-in
stations (100 miles or so). At night, working long distances, the whip
may outperform the dipole. During the day, the dipole will probably
outperform the whip.

It all depends.
73, Bill W6WRT


Correct on radiation angle, however the average mobile whip at 3.8mhz
is around 10% efficient. Even at 7Mhz it doesn't improve much
efficientcy wise. The low dipole (low being less than .25WL) is
close or better than 95% efficient but has a rotten radiation angle
for DX however close in it will be very good.

Myself in that situation.. I'd put a poles at either end of the
trailer (thats 50ft length) and if possible get it up 30ft or better
and hang a dipole. If the antenna is 66' (40m) the excess length
can hang. The support poles can be anything that will stay up. At
20m 30ft is 1/2WL up and will be decent. Even if you can't do two
support poles and only one make that one high as possible and mount
a dipole as a sloper. It will be somewhat directional but performace
will be far better than any ground mounted vertical that has no ground
plane.

If money wasn't a limiting factor. put down a base and put up a
freestanding tower.

The rules remain. More metal, higher the better.


Allison
KB1GMX

An antenna doesn't have a single "radiation angle". It radiates at all
angles. The relevant question is how much does it radiate at the
particular angle of interest, not at which angle does it radiate the
most. An antenna which radiates its maximum at a high angle might well
radiate more at a low angle than an antenna with a lower angle of
maximum radiation.

Roy Lewallen, W7EL

wrote:
On 13 Sep 2005 16:15:08 GMT, "Bill Turner" wrote:

Without more information, this comparison is flawed. A mobile whip has
a lower angle of radiation than a horizontal dipole. . .

Correct on radiation angle . . .

Money and space are actually limiting factors, but at least CC&R's
arent! My wife and I have been discussing this, and she really
doesn't like the idea of something 30 to 40 feet high on a small lot.

Her interest actually is gardening and we had been discussing
containing an area of decent topsoil within a square formed by railroad
ties. She has no objection to 20 to 25 foot high metal poles on the
corners of a square 20 to 25 foot on the side... which turns out to be
the core geometry of a 20 meter 4-square broadside phase array.

I would lay the poles first in concrete reinforced holes, connect the
feed network and radials on the dirt, and lay feed line underground
from the array to just near the trailer. Then I would lay the railroad
ties along the square, and then fill the square with topsoil.

Additional radials would need to be buried under a couple inches of red
clay fanning out from the square.

Variations:
1) could I create trap verticals from the poles for 20, 17, 15, and 10
meters, or do I need inscribed squares of seperate verticals because
seperate phased feeds might be needed for these other bands?
2) could I simply operate the square outside of 20 meters with a tuner
for local operation?

I think because space, money, and aesthetics are limiting factors, I
need to use precision to my advantage rather than size or height, and a
4 square may help there.

Comments?

The Eternal Squire

On Tue, 13 Sep 2005 20:43:23 -0700, Roy Lewallen
wrote:

An antenna doesn't have a single "radiation angle". It radiates at all
angles. The relevant question is how much does it radiate at the
particular angle of interest, not at which angle does it radiate the
most. An antenna which radiates its maximum at a high angle might well
radiate more at a low angle than an antenna with a lower angle of
maximum radiation.

Roy Lewallen, W7EL

Hello Roy,

I do understand that. I also understand when you say radiation angle
your talking about the primary or dominent lobe(s). There may be
many other lobes at useful or less than useful angles present as well.

However, how does that relate to using a shortend antenna with maybe
10% radiation efficientcy to a dipole at a reasonably attainable
height?

Allison
KB1GMX


wrote:
On 13 Sep 2005 16:15:08 GMT, "Bill Turner" wrote:

Without more information, this comparison is flawed. A mobile whip has
a lower angle of radiation than a horizontal dipole. . .

Correct on radiation angle . . .