Driving down I-5 between SF and LA, I've seen many radio towers that
rest on a single point.

I don't know what they are transmitting.

I do know that they look like regular towers from about ten feet up.
From ten feet and higher, they have a diminishing square cross
section. (May be triangular.)

Instead of resting on four (or three) legs though, they rest on a
single point, making the whole tower sort of a very elongated diamond
shape.

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

Thanks,


Jerry

They are resting on a single insulator. This is a very common practice
with BC monopoles.

They are not unstable. They are just not self-supporting.

Danny, K6MHE


On 13 Oct 2003 01:06:59 -0700,
(Jerry Asher) wrote:

Driving down I-5 between SF and LA, I've seen many radio towers that
rest on a single point.

I don't know what they are transmitting.

I do know that they look like regular towers from about ten feet up.
From ten feet and higher, they have a diminishing square cross
section. (May be triangular.)

Instead of resting on four (or three) legs though, they rest on a
single point, making the whole tower sort of a very elongated diamond
shape.

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

Thanks,


Jerry

I suppose the real answer is "I don't know", but I never let
that get in the way ... ;-)

If the tower gets narrow at its base then it will transmit relatively
little moment to the base. This means that the wind (and
earthquake) loads will be picked up by the guy wires. The
lower sections of the tower and the base can be smaller as a result.

Bruce Raymond/ND8I


"Jerry Asher" wrote in message
om...
Driving down I-5 between SF and LA, I've seen many radio towers that
rest on a single point.

I don't know what they are transmitting.

I do know that they look like regular towers from about ten feet up.
From ten feet and higher, they have a diminishing square cross
section. (May be triangular.)

Instead of resting on four (or three) legs though, they rest on a
single point, making the whole tower sort of a very elongated diamond
shape.

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

Thanks,


Jerry

(Jerry Asher) wrote in message

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

It's not unstable with the guy wires. That design is usually used when
the tower is insulated from ground with a big insulator I think. It's
probably a 1/4 wave AM-BC antenna . MK

(Mark Keith) wrote in message . com...
(Jerry Asher) wrote in message

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

It's not unstable with the guy wires. That design is usually used when
the tower is insulated from ground with a big insulator I think. It's
probably a 1/4 wave AM-BC antenna . MK

Thanks to all that replied. I've been puzzled by this for about nine
months of such trips now, and finally remembered to post.


Jerry

Jerry:

I just read that the WLW tower has been marked as a historical landmark. It
is one of the few remaining originals of that design, and has considerable
story coverage on the 'net. Do a Google search for WLW, and enjoy.

--
Crazy George
Remove N O and S P A M imbedded in return address
"Jerry Asher" wrote in message
om...
Driving down I-5 between SF and LA, I've seen many radio towers that
rest on a single point.

I don't know what they are transmitting.

I do know that they look like regular towers from about ten feet up.
From ten feet and higher, they have a diminishing square cross
section. (May be triangular.)

Instead of resting on four (or three) legs though, they rest on a
single point, making the whole tower sort of a very elongated diamond
shape.

The whole tower is kept from tipping over through the use of guy
wires.

Why build an unstable tower? What are the advantages of this design?

Thanks,


Jerry

In article , jerry-
says...
Why build an unstable tower? What are the advantages of this design?

In addition to the insulate-from-ground comments, it's possible they
used that design to lessen the risk of damage from earthquake and wind-
loading. The guy wires are more flexible and can give a bit more than
having the antenna anchored to the ground with steel sunk into concrete.

--

-- //Steve//

Steve Silverwood, KB6OJS
Fountain Valley, CA
Email:
Web: http://home.earthlink.net/~kb6ojs_steve

On 13 Oct 2003 18:44:18 -0700,
(Jerry Asher) wrote:

Thanks to all that replied. I've been puzzled by this for about nine
months of such trips now, and finally remembered to post.

Towers that come down to a single point are preferred because there
is no side stress on the base or the bottom of the tower. If each
leg were to come down to the base, any imbalance would be felt on a
single SMALLER and WEAKER point (the tower leg), stressing that
point.

gm
--
Replace x in adr with c