Ground Mounted Antenna Range

[nose49]

I currently have my transmitter and antenna mast mounted. I’m thinking about experimenting with building a grounded mounted system with radials. I was wondering what sort of range I should expect. So I was looking for some feedback from everyone who is operating a station with a ground mounted system. So how good is the range on a ground mounted system and what is your setup (how many radials and lengths, ect.)?

Respectfully

Mike

[MICRO1700]

Hi Mike:

I have been experimenting with different
ground mounted systems for about 4 years
now. There are a bunch of reasons why
I can’t go to a pole mounted system, but
that’s another story. The system is not
on right now because I basically turn it
off in the winter. Then I read a whole bunch
of stuff about Q and tuned circuits and grounds
and that sort of thing. I learn a little more
every year. Then I rebuild (hopefully something
that works better, although that has not always
been the case) the system and fire it up in
the spring. This process has been repeating itself
since 2006.

The set-up last year was (and still will be) an
SS-Tran AMT3000 transmitter kit that sits on
the ground in a water tight container. I do not
have the external loading coil that is
mentioned on the SS-Tran web site for the
“slightly less than 3 meter antenna.” I made
a different coil roughly the same size, but it
has a sliding ferrite bar to tune it. I is actually
part of the SS-Tran’s internal circuitry. I have
sixteen radials, some 10 feet long and some 20
feet long. The antenna is a thick copper pole.
I don’t know how wide it is. There have been
times when I have experimented with top-hats,
but my data on how they improve the coverage
is inconclusive.

This system, and variations of it has always worked
best on sunny dry days. I believe that when it rains
and my backyard gets soaked with water that the
system gets detuned, because I get less range when
it is raining. (This is exactly the opposite of what you
would think would occur, but there are probably other
factors at work here.)

I should also mention that if the ground mounted
system is fairly close to your house, it will seem
to couple into the power lines on your street and
on surrounding streets. I think the power lines
act as passive re-radiators, or loosely tuned
coupled receiving antennas, which will improve
your local coverage (I think).

OK. Here’s the data I have. (It isn’t a lot of data,
because I this is just an experimental set-up. I
have never encouraged people to listen, because,
quite frankly, I don’t think my programming would
appeal to a lot of people. It is mainly recordings of
my son and I playing jazz together, some comedy
routines we have done, and that’s sort of thing.)

In a house up the hill from me, 600 feet away, in the
kitchen, the station sounds perfect on a G.E. Superadio.
This is on 1690 KHz, which is clear during the day. (My
system automatically switches to another frequency
that is actually clearer at night, but that’s another story, too.)

In a house 800 feet to my right, the signal is noisy, but
perfectly listenable on a boombox of unknown make and
model. This is also in their kitchen.

One mile away, in the house of a friend, the station is
barely detectable on a Kaito 1103 radio in
the living room. If my friend moved to another part
of the house, he might get away from the noise
and get it better. We haven’t tried that yet. He does
hear the station very well on his car radio in his
driveway.

I can take a pocket sized Sangean DT-400W radio, and
walk into the town center which is 2000 to 4000
feet away. Sometimes the signal will be there,
sometimes it won’t. However, the signal will REALLY
peak up in parking lots and areas where there are
large buildings. I can sit at a table in the middle of
an open mall about 4000 feet away, and hear the
station noisy, but quite readable on the Sangean.
I think the reason the reception is good in these
places is because so many things are grounded
in those areas. (Light poles, supermarket wiring,
and that sort of thing.) The surrounding grounds
must help complete the “RF circuit.”

On the car radio, the observed coverage is not
a circle. It is a complicated pattern that is not
the same every day. I have heard the station
almost noise free on the car radio 2 miles away,
in front of a medical building in the parking lot.
Three miles north, I have also heard the station
almost noise free in the parking lot of a strip mall.

One thousand feet from my house to the east,
there is a long street that is perpendicular to my
street. I can hear the station at various levels,
on that street, sometimes very strong, sometimes
almost nothing. This extends about a mile to
the north and about a mile to the south.

Lastly, I have a park on my street that is about a
half a mile to my west. I can hear the station,
with some noise, on a Grundig S-350, while sitting
at a picnic table in the park. If a use the tone
control on the radio to turn down the treble, or
high part of the audio spectrum, the noise is hardly
noticable.

It should be noted, that the Sangean DT-400W, the
G.E. Superadio, the Grundig S-350, and the Kaito
1103 are very
good AM receivers, and so are car radio receivers,
usually.

The boom box that heard the station 800 feet to
my right – well, I don’t know anything about the
specs on that radio.

Also, again, the best coverage is when it is not
raining. If it is raining really hard, the coverage
can drop to 1/4 mile in each direction.

I obviously have a lot of bugs to work out in this
system.

I hope this helps.

Best Wishes
Bruce, MICRO1690/1700

[Ken Norris]

Well, there you go … it just goes to show how many variables can affect a Part 15 AM radio signal … doesn’t take much, eh? 😉

Find a plateau, a 100 ft. diameter flat spot on top of a hill higher than buildings around it with highly conductive rich soil in the center of your listening area with a mesh at the foot of the ground-mounted antenna and 60 or so 40 ft radials with ground stakes at both ends of each.

Just a dream 😉

[MICRO1700]

Hi Ken!

Yup, for me it’s a continuing experiment.

I actually really like the experimental part.

I have enjoyed reading your posts, Ken. If
you are able, keep letting us know what you
are doing.

Best Wishes
Bruce, MICRO 1690/1700

[nose49]

Thanks Ken and Bruce,
That was a lot of good detailed info Bruce, encouraging, good range. I’m gonna give it a shot. Ken, I’m looking out my window at that hill (actually a ridge line) about a 1/2 mile from my property, I just happen to be in the river valley below. That was why I used the mast in the first place, works great get a couple (sometimes 3) miles in one direction (east) a lot less in the opposite direction. Think I’m going to bring it to ground level in light of the scrutiny that the FCC is giving part 15 right now. At least till we see how that all settles down. Also talked to the Isotron builder today, (Bilal) but I think that is still going to be a ground issue. So I’m putting it on the ground, lots of radials give that a shot and maybe go multiple transmitters.
Thanks,
Mike

[MICRO1700]

Hi Mike:

I noticed you mentioned the Bilal
Isotron. I have looked at their
website many times and have
wondered about that antenna.
Specifically the Part 15 AM broadcast
band version.

It looks like it is center fed. So you
would have to get the Isotron up
on the pole and then place the
transmitter right on it’s feed point.
I believe the Amateur Radio versions
of that antenna are all 50 ohms
impedance, so I’m assuming that
the Part 15 version is too. So, if
that is correct, any Part 15 AM transmitter
you placed on there would have to
see 50 ohms one way or the other.

If I had the money, I would get one
just to try it.

Anyway, putting that aside, I wish you
the best of luck with your experiments.

To me, Part 15 experimenting is great
because of what I have learned doing
it.

Best Wishes
Bruce, MICRO1690/1700

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