Nevada Scanmaster Airmaster antenna

[Troy R.]

I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?

http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

[Rob]

Troy R. wrote:
|| I am after a good V/UHF airband antenna and found this on a Google
|| search. Anybody actually own one and can tell me how they perform?
||
|| http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
||
|| --
|| Regards
|| Troy Rowland



I dont personally, but know someone who does, and loves it, uses it to
listen to the shipping etc clear pickup, mind you, he does live V close to
the port lol

[Bill Crocker]

Looks like the wind blew the fabric off some old ladies umbrella!

Bill Crocker

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

[Marco]

Troy
Try a decent ham dual band antenna, cheaper and a lot better.
Marco

I am after a good V/UHF airband antenna and found this on a Google search. Anybody actually own one
and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

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[Troy R.]

I've gone down the dual band amateur path before and been disappointed,
hence the interest in something like this.

Post by Marco
Troy
Try a decent ham dual band antenna, cheaper and a lot better.
Marco

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

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[Al Klein]

On Fri, 29 Oct 2004 22:45:21 +1000, "Troy R."

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

They don't seem to know much about it. Discones aren't resonant
antennas, but they do pick up signals from the design frequency to
daylight..

[Volker Tonn]

Post by Al Klein
On Fri, 29 Oct 2004 22:45:21 +1000, "Troy R."

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

They don't seem to know much about it. Discones aren't resonant
antennas, but they do pick up signals from the design frequency to
daylight..

Not having read the linked page....
Discones ARE resonant on an extremly wide range.
Therefore they have nearly no gain above the (theortical) isotropic
antenna. This means they have a loss of around 1/2 S-unit against a
dipole or a half-wave vertikal antenna on a specified frequency. Not too
bad for a compromise.
The resonant range of a well designed and built discone is spread 1:10
on wich you can transmit. This is 50 to 500 Mhz or 100 to 1000Mhz for
example, covering the most wanted frequencies for scannists and is also
usable on ham-bands or FRS to transmit.
The receiving range -allowing an impedance mismatch- is much wider when
(usually) allowing a loss of 1 S-unit (-6dB). The difference you only
will notice on faint signals.
There are some other antennas too -directional and omnidirectional-,
providing a relatively wide resonant range but not nearly as wide as a
discone.

[Al Klein]

On Sat, 30 Oct 2004 11:55:50 +0200, Volker Tonn

Post by Volker Tonn

Post by Al Klein
On Fri, 29 Oct 2004 22:45:21 +1000, "Troy R."
They don't seem to know much about it. Discones aren't resonant
antennas, but they do pick up signals from the design frequency to
daylight..

Not having read the linked page....
Discones ARE resonant on an extremly wide range.
Therefore they have nearly no gain above the (theortical) isotropic
antenna. This means they have a loss of around 1/2 S-unit against a
dipole or a half-wave vertikal antenna on a specified frequency. Not too
bad for a compromise.
The resonant range of a well designed and built discone is spread 1:10
on wich you can transmit. This is 50 to 500 Mhz or 100 to 1000Mhz for
example, covering the most wanted frequencies for scannists and is also
usable on ham-bands or FRS to transmit.

We're using different definitions of "resonant". The definition I use
says that an antenna can only resonate on a frequency. (Pretty much,
the frequency a dip meter will indicate when coupled to the antenna.)
It can have a bandwidth over which it can be used, but the resonant
point is (usually) one single frequency. Discones look like dipoles
with the 2 legs being different lengths, so the best one could say -
using my definition - is that they "resonate" on the frequency at
which the disc is 1/2 wavelength in diameter and the frequency at
which the cone element length is 1/4 wavelength.

But they probably are the best tradeoff for multi-band scanning.

[Dale Parfitt]

Snip...

Post by Al Klein
We're using different definitions of "resonant". The definition I use
says that an antenna can only resonate on a frequency. (Pretty much,
the frequency a dip meter will indicate when coupled to the antenna.)
It can have a bandwidth over which it can be used, but the resonant
point is (usually) one single frequency. Discones look like dipoles
with the 2 legs being different lengths, so the best one could say -
using my definition - is that they "resonate" on the frequency at
which the disc is 1/2 wavelength in diameter and the frequency at
which the cone element length is 1/4 wavelength.
But they probably are the best tradeoff for multi-band scanning.

Let's use an accepted engineering definition- resonance is defined when the
input Z has zero reactance- a properly designed discone (disc and cone- not
a skeletal version) is virtually reactance free over a very wide band.
Discones may look like dipoles- although you really have to be imaginitive,
is a derivative of the bicone antenna (replace the disk with another cone).
With proper included cone angle and proper machining of the junction (this
limits hi end performance) it is a wonderfully broadbanded antenna.

Dale W4OP

[Troy R.]

So what you are saying Dale is that a bicone antenna is a good wideband
antenna? Do they exhibit any gain?

Post by Dale Parfitt
Snip...

Post by Al Klein
We're using different definitions of "resonant". The definition I use
says that an antenna can only resonate on a frequency. (Pretty much,
the frequency a dip meter will indicate when coupled to the antenna.)
It can have a bandwidth over which it can be used, but the resonant
point is (usually) one single frequency. Discones look like dipoles
with the 2 legs being different lengths, so the best one could say -
using my definition - is that they "resonate" on the frequency at
which the disc is 1/2 wavelength in diameter and the frequency at
which the cone element length is 1/4 wavelength.
But they probably are the best tradeoff for multi-band scanning.

Let's use an accepted engineering definition- resonance is defined when the
input Z has zero reactance- a properly designed discone (disc and cone- not
a skeletal version) is virtually reactance free over a very wide band.
Discones may look like dipoles- although you really have to be
imaginitive,
is a derivative of the bicone antenna (replace the disk with another cone).
With proper included cone angle and proper machining of the junction (this
limits hi end performance) it is a wonderfully broadbanded antenna.
Dale W4OP

[Volker Tonn]

Post by Troy R.
So what you are saying Dale is that a bicone antenna is a good wideband
antenna? Do they exhibit any gain?

Gain? ...compared to what?
Yes, the bicone antenna has gain!
It's gain is comparable to a dipole.
But a bicone is far away to be as broadband as a discone.

[Dale Parfitt]

Post by Volker Tonn

Post by Troy R.
So what you are saying Dale is that a bicone antenna is a good wideband
antenna? Do they exhibit any gain?

Gain? ...compared to what?
Yes, the bicone antenna has gain!
It's gain is comparable to a dipole.
But a bicone is far away to be as broadband as a discone.

Can you show me a text indicating that a bicone has a bandwidth different
from a discone?

Dale W4OP

[Dale Parfitt]

Post by Troy R.
So what you are saying Dale is that a bicone antenna is a good wideband
antenna? Do they exhibit any gain?

Yes,
The bicone ( or biconical dipole) is an excellent broadband antenna with
bandwidth characteristics exceeding 10:1 when properly constructed. Ideally
the two cones are just that- a pair of cones, not an array of spokes. Of
particular importance to the hi frequency performance is that the tips of
the cones come to fine points. Maintaining this geometry extends the hi end
bandwidth.
A bicone will exhibit approximately 2dB gain over a discone. A discone can
be thought of as a degenerative form of the bicone, where the flare angle of
one of the cones is extended to 180 degrees-i.e. a flat cone = disc.

73,

Dale W4OP
for PAR Electronics, Inc.

[Volker Tonn]

Post by Al Klein
On Sat, 30 Oct 2004 11:55:50 +0200, Volker Tonn

Post by Volker Tonn

Post by Al Klein
On Fri, 29 Oct 2004 22:45:21 +1000, "Troy R."
They don't seem to know much about it. Discones aren't resonant
antennas, but they do pick up signals from the design frequency to
daylight..

Not having read the linked page....
Discones ARE resonant on an extremly wide range.
Therefore they have nearly no gain above the (theortical) isotropic
antenna. This means they have a loss of around 1/2 S-unit against a
dipole or a half-wave vertikal antenna on a specified frequency. Not too
bad for a compromise.
The resonant range of a well designed and built discone is spread 1:10
on wich you can transmit. This is 50 to 500 Mhz or 100 to 1000Mhz for
example, covering the most wanted frequencies for scannists and is also
usable on ham-bands or FRS to transmit.

We're using different definitions of "resonant". The definition I use
says that an antenna can only resonate on a frequency. (Pretty much,
the frequency a dip meter will indicate when coupled to the antenna.)
It can have a bandwidth over which it can be used, but the resonant
point is (usually) one single frequency. Discones look like dipoles
with the 2 legs being different lengths, so the best one could say -
using my definition - is that they "resonate" on the frequency at
which the disc is 1/2 wavelength in diameter and the frequency at
which the cone element length is 1/4 wavelength.

To say so, a discone has it's "middle frequency". But impedance curve
stays constantly over a very wide range around. So in theoretics you can
get a frequency modulated signal with center frequency of let's say
500Mhz and a bandwidth of 800Mhz through a discone with a straight power
curve wich has no loss by mismatching of the antennea.
I don't know of any TRX providing such a signal :-)

As I understand the principle of a discone the disc is a load plate wich
spreads the bandwidth in conjunction wich the conical "antenna wire". So
the "resonant" wavelength is more related to the length of the cone
measured from the the top plate in 90 degree angle to the bottom.
You may correct me if I'm wrong :-)
Have a nice weekend.

[paul churchill]

So after all that is someone out there going to answer the original question
which was basically (Is the scanmaster airband discone that nevada sell
worth it's price tag) rgds all from M3PAC.... PAUL.....

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

[Marco]

Perhaps

a) Nobody on this NG uses it, or
b) Any that do use do not think it worth commenting on.

Possibly the "silence speaks volumes".

Marco
(Who uses a Diamond D707)

Post by paul churchill
So after all that is someone out there going to answer the original question
which was basically (Is the scanmaster airband discone that nevada sell
worth it's price tag) rgds all from M3PAC.... PAUL.....

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

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[Iden]

Post by paul churchill
So after all that is someone out there going to
answer the original question which was basically
(Is the scanmaster airband discone that nevada sell
worth it's price tag) rgds all from M3PAC....

Being an antenna nut and regular listener to aircraft
communications, I, too, would like to know.

I presume you mean this antenna:
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

It is sort of a bi-cone antenna and sort of
a "dipole cluster" antenna.

The same basic idea (dipole cluster) is used in the
Antennacraft Scantenna ST-2:
http://www.grove-ent.com/ANT7.html
but this one is not optimized for the aircraft bands.

The discontinued Channel Master 5094A Monitenna
is much the same and has proved to be a good
monitor antenna for me for the "public service"
bands. It, too, is not optimized for the aircraft bands

The Scanmaster Airmaster should work pretty
well just by looking at it but one never knows until
they are in place and operating.

I created and moderate and aircraft listener's group
http://groups.yahoo.com/group/AirCommSouthwest/
of nearly 600 members and I posted an inquiry
about the Scanmaster Airmaster but apparently
no one has had experience with one, though the
inquiry did start and aircraft monitoring antenna
thread.

One problem in the U.S. is that no one seems to
sell the Airmaster, at least, I can't find a retailer.
One may be able to buy them from the U.K.
though.

I did buy a so called "Double Discone" (bi-cone)
on eBay and have yet to try it but it looks like
one could make and Airmaster out of it by
cutting the elements. It would be nice to have
the element dimensions from the Airmaster.

Here is a description of the "Double Discone:"
http://www.radio-ware.com/products/ant426.htm

Here is another option:
http://www.ssejim.co.uk/vhfairbandant.htm
http://www.ssejim.co.uk/uhfairbandant.htm
http://www.ssejim.co.uk/dip2002abeu.htm

I did buy the last item from the U.K. and it seems
to work well. I have separate antennas for
VHF and UHF aircraft and then combine them
into a single coax feed.

Another option to combine VHF and UHF aircraft
antennas would be the CF-142:
http://www.cometantenna.com/products.php?CatID=3&famID=23&childID=44

Iden - Northern California

[ukmonitor]

YES THE SCANMASTER AIRBAND DOUBLE DISCONE WORKS WELL.

But you could make one for a few pounds.

Dual or Tri-band band amateur antennas have internal matching networks
which can give poor results when used outside their intendend
frequency ranges.

They can work reasonably well upto approx. +/- 20% outside their
design frequencies (plus a few odd harmonic resonses), which may be OK
for PMR monitoring. But it will not provide good coverage of the whole
of the UHF MIL air band.

I use a Double discone and can monitor re-broadcast satcom traffic in
the UHF Mil band, so I think it is good enough.....

UKM

Post by paul churchill
So after all that is someone out there going to answer the original question
which was basically (Is the scanmaster airband discone that nevada sell
worth it's price tag) rgds all from M3PAC.... PAUL.....

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google search.
Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html
--
Regards
Troy Rowland

[Henk]

"Troy R." <***@NOSPAMoptusnet.com.au> wrote in news:41823b62$0$22672$***@news.optusnet.com.au:

Hi Troy, I used to have one, it worked fine for about 1 year then it got
broke. Dunno what was wrong with it though.

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google
search. Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

[Marco]

Post by Henk
Hi Troy, I used to have one, it worked fine for about 1 year then it got
broke. Dunno what was wrong with it though.

Post by Troy R.
I am after a good V/UHF airband antenna and found this on a Google
search. Anybody actually own one and can tell me how they perform?
http://www.nevadaradio.co.uk/acatalog/scanmaster-airmaster.html

Troy
Why not try a !good! amateur dual band 2m/70cm antenna, a lot cheaper, less obtrusive, and IMHO a
lot better.
Marco


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[Henk]

Yes! Or just buy a regular discone OR open dipole. That'll work just as
well but cheaper ;-)

Post by Marco
Troy
Why not try a !good! amateur dual band 2m/70cm antenna, a lot
cheaper, less obtrusive, and IMHO a lot better.
Marco

[Laurie]

Post by Marco
Why not try a !good! amateur dual band 2m/70cm antenna, a lot
cheaper, less obtrusive, and IMHO a lot better.

This may not really be a good idea.
The aircraft band is a long way from the 2m bands and you will be using the
antenna well outside its designed frequency band. Depending on the precise
construction of the antenna, it may receive no better than a damp piece of
string. My own 2m/70cms co-linear (well sited, outside) actually receives
less than a discone in the loft on airband. No contest on 2m or 70cms
though, the co-linear is far better.