Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a short
tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass form. It
is centerloaded. I am looking at it accross the yard, it is about 6 inches long.
It is would with about a point .5 pitch. Calculations for a 1:1 pitch predict a
Q of about 450.

Thanks,
Dan

Frank wrote:
I have been using an 80 meter loaded vertical for a couple of years with
moderate success. The ground system is a dozen 'untuned' radials 40 or so
feet laying on the ground. The feed line is about 100 feet of RG-8 coax.
The SWR in the shack is about 1.1 to 1.

I have done some research on the antenna and based on it parameters it
should have a radiation resistance of about 4 Ohms. This says that the
coil and ground are absorbing on the order of 45 Ohms. This is 10db
performance loss.

I have limited space and the most common solutions are not available to
me. From a practical perspective it would seem to me that building a 40
foot center feed loaded dipole and putting it in the attic or on the roof
would probably perform somewhat better.

Is this a reasonable assumption?

Would burying the radials and connecting them to several 4 square foot
buried screens substantially help the ground system?

Thanks,
Dan kb0qil


How high is the antenna, where is the loading coil placed, what is its
value, and Q?

Frank

Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a short
tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass form. It
is centerloaded. I am looking at it accross the yard, it is about 6 inches long.
It is would with about a point .5 pitch. Calculations for a 1:1 pitch predict a
Q of about 450.

Thanks,
Dan

Frank wrote:
I have been using an 80 meter loaded vertical for a couple of years with
moderate success. The ground system is a dozen 'untuned' radials 40 or so
feet laying on the ground. The feed line is about 100 feet of RG-8 coax.
The SWR in the shack is about 1.1 to 1.

I have done some research on the antenna and based on it parameters it
should have a radiation resistance of about 4 Ohms. This says that the
coil and ground are absorbing on the order of 45 Ohms. This is 10db
performance loss.

I have limited space and the most common solutions are not available to
me. From a practical perspective it would seem to me that building a 40
foot center feed loaded dipole and putting it in the attic or on the roof
would probably perform somewhat better.

Is this a reasonable assumption?

Would burying the radials and connecting them to several 4 square foot
buried screens substantially help the ground system?

Thanks,
Dan kb0qil


How high is the antenna, where is the loading coil placed, what is its
value, and Q?

Frank

The local gardener who takes great pride and ownership in the lawn. The garage
can go mostly to seed, however the lawn must be pristine. Each antenna change
meets with great resistance. Although defiantly was definitely a spell checker
choice, it is also the correct one for getting radials.

Dan

Cecil Moore wrote:
dansawyeror wrote:

I will defiantly try adding radials.


Who are you defying?

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"dansawyeror" wrote in message
...
Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a
short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is about
6 inches long. It is would with about a point .5 pitch. Calculations for a
1:1 pitch predict a Q of about 450.

Thanks,
Dan

Maybe I missed something, but how high is the TOP of the antenna. I.E. How
long is the whip? Is the loading coil at the base, or partway up the
antenna?

Tam/WB2TT

Tam,

The description was for the coil.

The total antenna is about 15 feet base to tip. The coil is about 1/3 of the way
up. The base is about 3 feet off the ground so the tip would be about 18 feet up.

Dan

Tam/WB2TT wrote:
"dansawyeror" wrote in message
...

Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a
short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is about
6 inches long. It is would with about a point .5 pitch. Calculations for a
1:1 pitch predict a Q of about 450.

Thanks,
Dan


Maybe I missed something, but how high is the TOP of the antenna. I.E. How
long is the whip? Is the loading coil at the base, or partway up the
antenna?

Tam/WB2TT

"dansawyeror" wrote in message
...
Tam,

The description was for the coil.

The total antenna is about 15 feet base to tip. The coil is about 1/3 of
the way up. The base is about 3 feet off the ground so the tip would be
about 18 feet up.

Dan

Tam/WB2TT wrote:
"dansawyeror" wrote in message
...

Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a
short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is
about 6 inches long. It is would with about a point .5 pitch.
Calculations for a 1:1 pitch predict a Q of about 450.

Thanks,
Dan


Maybe I missed something, but how high is the TOP of the antenna. I.E.
How long is the whip? Is the loading coil at the base, or partway up the
antenna?

Tam/WB2TT
Dan,

Over perfect ground, I get an impedance of about 2.4 Ohms, with resonance
very close to 3.8 MHz. What is the tallest tree in your yard?

Tam

Tam

That would relate very close to what the models predict. Where or how do you
have such good ground?

Dan

Tam/WB2TT wrote:
"dansawyeror" wrote in message
...

Tam,

The description was for the coil.

The total antenna is about 15 feet base to tip. The coil is about 1/3 of
the way up. The base is about 3 feet off the ground so the tip would be
about 18 feet up.

Dan

Tam/WB2TT wrote:

"dansawyeror" wrote in message
...


Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a
short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is
about 6 inches long. It is would with about a point .5 pitch.
Calculations for a 1:1 pitch predict a Q of about 450.

Thanks,
Dan


Maybe I missed something, but how high is the TOP of the antenna. I.E.
How long is the whip? Is the loading coil at the base, or partway up the
antenna?

Tam/WB2TT

Dan,

Over perfect ground, I get an impedance of about 2.4 Ohms, with resonance
very close to 3.8 MHz. What is the tallest tree in your yard?

Tam

dansawyeror wrote:
All,

I have been using an 80 meter loaded vertical for a couple of years with
moderate success. The ground system is a dozen 'untuned' radials 40 or
so feet laying on the ground. The feed line is about 100 feet of RG-8
coax. The SWR in the shack is about 1.1 to 1.

I have done some research on the antenna and based on it parameters it
should have a radiation resistance of about 4 Ohms. This says that the
coil and ground are absorbing on the order of 45 Ohms. This is 10db
performance loss.

I have limited space and the most common solutions are not available to
me. From a practical perspective it would seem to me that building a 40
foot center feed loaded dipole and putting it in the attic or on the
roof would probably perform somewhat better.

Is this a reasonable assumption?


I'm not sure you can count on that. You'd still lose some in a
matching/loading network, there'd be a lot of ground loss because of the
low height, and absorption of some of the power from conductors in the
house might occur. It wouldn't hurt to try, but leave your vertical up.

Would burying the radials and connecting them to several 4 square foot
buried screens substantially help the ground system?

Just about anything you can do to increase the conductivity of the
ground system, particularly close to the antenna, will help. Using
screen is one thing. Burying the radials won't help. Adding more radials
and making them longer will help. Unfortunately, making a few radials
longer doesn't do much, and adding a bunch of short radials doesn't do
much either -- you really have to do both to have a big effect. If
possible, connect to any other nearby buried conductors such as metallic
water pipes.

The other thing you can do to improve the efficiency is to increase the
radiation resistance of the antenna. You can do this of course by
increasing the height of the antenna. Moving the loading coil upward
will help, too, although you'll need more inductance. (The coil still
won't be a major part of the overall loss, though.) A top hat is better
yet. You can also increase the radiation resistance by making your
antenna fatter. Use multiple wires in parallel, spaced about as far as
you can, either along side each other, or fanned out, converging at the
bottom.

Finally, if you've got room, you can improve your overall efficiency by
about 3 dB by putting in another identical antenna/ground system
somewhere nearby and connecting the two in parallel.

Roy Lewallen, W7EL

"dansawyeror" wrote in message
...
Tam

That would relate very close to what the models predict. Where or how do
you have such good ground?

Dan

You don't. That is just the best case. If you can add another 20 feet of
wire to the top, and redo the inductor, the Z comes up to 16 Ohms. That's
why I asked about the trees.

Tam

Tam/WB2TT wrote:
"dansawyeror" wrote in message
...

Tam,

The description was for the coil.

The total antenna is about 15 feet base to tip. The coil is about 1/3 of
the way up. The base is about 3 feet off the ground so the tip would be
about 18 feet up.

Dan

Tam/WB2TT wrote:

"dansawyeror" wrote in message
...


Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on
a short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is
about 6 inches long. It is would with about a point .5 pitch.
Calculations for a 1:1 pitch predict a Q of about 450.

Thanks,
Dan


Maybe I missed something, but how high is the TOP of the antenna. I.E.
How long is the whip? Is the loading coil at the base, or partway up the
antenna?

Tam/WB2TT

Dan,

Over perfect ground, I get an impedance of about 2.4 Ohms, with resonance
very close to 3.8 MHz. What is the tallest tree in your yard?

Tam

Frank,

The coil measures about 60 uH. The antenna is elevated about 3 feet on a
short tripod. The radials angle down the tripod legs and then out.

The coil is about 4 inchs in diameter, number 12, wound on a fiberglass
form. It is centerloaded. I am looking at it accross the yard, it is about
6 inches long. It is would with about a point .5 pitch. Calculations for a
1:1 pitch predict a Q of about 450.

Thanks,
Dan

Thanks for the info Dan. From your comments the radials appear to be
parallel with the tripod legs to ground level, and then continue at ground
level for the rest of their length. What is the angle of the tripod legs?
I agree with comments about adding a horizontal wire to the top of the
vertical; it will probably be easier than a capacity hat. I am overloaded
with work at the moment, but would like to attempt a model in a week or so
when I have less work.

73,

Frank