T Antenna for 160 Meters
 

I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be 40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and it
is playing very well but the noise is S9 to 5 Over. I understand the the T
Antenna is a much more quiet antenna?

Thanks
Scott

An inverted-L antenna can be converted to a T-antenna just by sliding the
vertical wire from the end of the L to the centre of the T. At intermediate
positions we get the original Windom antenna.

The small difference in configuration between the two is unlikely to have
much of an effect on signal to noise ratio.

The T behaves more like a true vertical than the L. It is well known the
vertical is a low-angle receiving antenna and therefore picks up more
locally generated noise.

So if there *IS* any difference between the two then it will be in favour of
your existing inverted-L.

The local noise environment, ie., where the noise is coming from, will also
have an effect at least as great changing the wire configuration. But not
very much.

(By the way, the lengths of the T-antenna wires are non-critical. The
bottom-end loading coil can be dispensed with and incorporated in the tuner
if the tuner has sufficient inductance.)
----
Reg, G4FGQ

==================================

"Scott Gordon" wrote -
I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be
40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and
it
is playing very well but the noise is S9 to 5 Over. I understand the the
T
Antenna is a much more quiet antenna?

Thanks
Scott

Reg,

Thanks for your input. I had read in another article that a T would be
much quieter or it was for this ham. Quote "At my QTH my 1/4 wave inverted L
noise level was always S9 to +5 over. With my linear loaded voltage fed Tee,
the noise level has been reduced to S0-1." unQuote.

I don't really have room for a dipole on 160 meters, it would probably be a
little more quite than what I have. I read a artical as well in W6SAI
antenna book about a compact T antenna that I will try out once the weather
warms up a bit.

Thanks
Scott

"Reg Edwards" wrote in message
...
An inverted-L antenna can be converted to a T-antenna just by sliding the
vertical wire from the end of the L to the centre of the T. At
intermediate
positions we get the original Windom antenna.

The small difference in configuration between the two is unlikely to have
much of an effect on signal to noise ratio.

The T behaves more like a true vertical than the L. It is well known the
vertical is a low-angle receiving antenna and therefore picks up more
locally generated noise.

So if there *IS* any difference between the two then it will be in favour
of
your existing inverted-L.

The local noise environment, ie., where the noise is coming from, will
also
have an effect at least as great changing the wire configuration. But not
very much.

(By the way, the lengths of the T-antenna wires are non-critical. The
bottom-end loading coil can be dispensed with and incorporated in the
tuner
if the tuner has sufficient inductance.)
----
Reg, G4FGQ

==================================

"Scott Gordon" wrote -
I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be
40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and
it
is playing very well but the noise is S9 to 5 Over. I understand the
the
T
Antenna is a much more quiet antenna?

Thanks
Scott

"Scott Gordon" wrote in message igy.com...
I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be 40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and it
is playing very well but the noise is S9 to 5 Over. I understand the the T
Antenna is a much more quiet antenna?

Nope. Should be little if any difference. The only real difference
will be an overhead null on the T, compared to no null on the L due to
the unbalanced horizontal loading wire. The pattern of the T is much
the same as a monopole.
I use both here. The T is usually the best at any long distance. The
current distribution is much better on my T than on the L. So it has
less ground loss, and is more efficient. My T is about 40 ft tall, and
has 4 60 ft loading wires. "120 ft across". The difference between
using 4 top load wires and 2 top load wires seemed to be pretty small.
MK

Mark,

Thanks for the information. How are you feeding your T and does it have any
type of matching network?

Scott

"Mark Keith" wrote in message
om...
"Scott Gordon" wrote in message
igy.com...
I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be
40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and
it
is playing very well but the noise is S9 to 5 Over. I understand the
the T
Antenna is a much more quiet antenna?

Nope. Should be little if any difference. The only real difference
will be an overhead null on the T, compared to no null on the L due to
the unbalanced horizontal loading wire. The pattern of the T is much
the same as a monopole.
I use both here. The T is usually the best at any long distance. The
current distribution is much better on my T than on the L. So it has
less ground loss, and is more efficient. My T is about 40 ft tall, and
has 4 60 ft loading wires. "120 ft across". The difference between
using 4 top load wires and 2 top load wires seemed to be pretty small.
MK

On Mon, 02 Feb 2004 14:30:39 GMT, "Scott Gordon"
wrote:

I seen in a recent article showing a Compact T Antenna for 160 Meters.

Tophat is 80 ft long and the T is connected in the center and should be 40ft
long with a 20uH to the feedpoint then the shield to ground.

Has anyone used one of these antennas? I use a Inverted L right now and it
is playing very well but the noise is S9 to 5 Over. I understand the the T
Antenna is a much more quiet antenna?

Thanks
Scott

A classic vertical antenna should indeed have a pretty deep overhead
null. Perhaps also your T antenna might have this null- it probably
depends on how symmetrical you can make the antenna. I can think
of scenarios where the difference between an inverted L and a T
antenna should be minimal, namely when the predominate noise source
is man-made and local. OTOH your T antenna might discriminate better
against atmospheric noise that originates fairly 'close by', but is
beyond ground wave range. Certainly if your T has a good overhead
null, there is one kind of noise that it will reject much better than
your inverted L, namely the very loud close-in signals from your
competition in a big pileup, and especially if the DX is working
everyone transceive instead of QSX up/down. The DX is often
puny weak and the pile more like 40+dB over S9. If your ham
neighbor 50-100 miles up the road from you simply has to have
the DX you are calling, his high-angle NVIS signal may be deafening
on an inverted L but manageable on a vertical having a good
overhead null. BTW the foregoing discussion assumes you are
using your antenna to receive as well as to transmit. It certainly
sounds that way from the way you posed your question.
73, David K3KY

P.S. An interesting artifact of bobtail/ half square arrays is that
often the ham who has just put one up becomes worried that the
antenna is not working. The band sounds too quiet at first. But
upon tuning around, he finds that there are good signals across
the band standing out well from the background. Here we see
a double treat in effect- good overhead null plus the nice, deep
end nulls off the ends in line with the horizontal wire. It is a
striking effect which I have heard myself at this QTH. Just
a thought...