ART'S ANTENNA
 

Met an old ham a couple of weeks ago he had recently moved into a
senior citizens complex and was unable to have antennas of any sort
erected, all he had was, as he put it, a piece of wire in the loft.
After a bit of thought I decided to make one of Art's antennas for
him. I made a former 16" long by 10.5"diameter and contra-wound
aprox 550' of twisted (1100' single) 19 gauge copper magnet wire onto
it, covered same in pvc tape and took it over to him yesterday
morning, he took some swr readings they were as follows.

SWR
1.8 = 1.2 :1
3.75 = 1 :1
7.075 = 1.7 :1
14.075 = 4 :1
21.075 = 6 :1

He did not have a variometer but is going to build one, will post
results when He gives them to me, I left him playing with the antenna
and he seemed to be a very happy man.

Derek

ART'S ANTENNA
 

derek wrote:
Met an old ham a couple of weeks ago he had recently moved into a
senior citizens complex and was unable to have antennas of any sort
erected, all he had was, as he put it, a piece of wire in the loft.
After a bit of thought I decided to make one of Art's antennas for
him. I made a former 16" long by 10.5"diameter and contra-wound
aprox 550' of twisted (1100' single) 19 gauge copper magnet wire onto
it, covered same in pvc tape and took it over to him yesterday
morning, he took some swr readings they were as follows.

SWR
1.8 = 1.2 :1
3.75 = 1 :1
7.075 = 1.7 :1
14.075 = 4 :1
21.075 = 6 :1

He did not have a variometer but is going to build one, will post
results when He gives them to me, I left him playing with the antenna
and he seemed to be a very happy man.

Derek

Derek:

That was very kind of you. That kind of help is rare these days--at
least where I live in the USA ...

I will hope against hope that it serves him better than anyone could
have hoped for.

I need more neighbors like yourself (or, at least a few!) :-)

Warm regards,
JS

ART'S ANTENNA
 

derek wrote:

...
Derek

By the way, I was just into Lowes hardware store this day. I was in
search of some "Sono Tube" or "Quick Tube." It is a cardboard tube,
very sturdy. They had lengths of ~4-6 ft. The largest diameter they
had was 12" (they had 8,10,12 inch dia. in stock.) I needed 18" or
larger as I was going to use it for construction of a "cat tree."

But, anyway, sounds like excellent material for a "former."

Regards,
JS

ART'S ANTENNA
 

On Jul 13, 3:48 pm, derek wrote:
Met an old ham a couple of weeks ago he had recently moved into a
senior citizens complex and was unable to have antennas of any sort
erected, all he had was, as he put it, a piece of wire in the loft.
After a bit of thought I decided to make one of Art's antennas for
him. I made a former 16" long by 10.5"diameter and contra-wound
aprox 550' of twisted (1100' single) 19 gauge copper magnet wire onto
it, covered same in pvc tape and took it over to him yesterday
morning, he took some swr readings they were as follows.

SWR
1.8 = 1.2 :1
3.75 = 1 :1
7.075 = 1.7 :1
14.075 = 4 :1
21.075 = 6 :1

He did not have a variometer but is going to build one, will post
results when He gives them to me, I left him playing with the antenna
and he seemed to be a very happy man.

Derek

Good on you Derek. It would appear the instructions on my page
worked out OK for you.
Can you give details about the former you made and what was the length
of the turnings?
If you like I can send details on how to make the variometer and it
wouldn't surprise me if tha
local club doesn't ask you for a demonstration how to make one.
You have no idea how happy you made that ham since he can now work
anywhere
he wants to as well as the local repeaters I garantee he was not a
happy man in the old peoples home
and having the ability of just a piece of wire
Cheers
Art
Unwinantennas.com/

ART'S ANTENNA
 

On Jul 14, 8:16 am, Art Unwin wrote:


Hi Art

I made the former out of plywood and half inch doweling, when
twisting the wire I aimed for two full turns per inch, the wire I
used filled the former with about 6 to 8 foot of wire over. As a
matter of interest you say on your page you used aprox 2000 feet of
wire on a 12 by 12 inch former, from my experience with my former I
would say you only used aprox 1000 feet of wire.

Derek

ART'S ANTENNA
 

On Jul 14, 8:16 am, Art Unwin wrote

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

ART'S ANTENNA
 

Another good use for those concrete form tubes is making antenna carriers.
Made one for a three element yagi, A3S, and it works fine.
Put a couple of tubes together so it was just over 14 feet long.
Added two garage door "D" handles, put a plug in one permanently and a
removable plug, held in place with Velcro in the other.
Now for Field Day or SkyWarn Recognition Day we can just pick it up, put it
on the trailer, hold it down with a couple of tarp straps and drive off.
Very easy to get the antenna in and out of the tube.
Protects the antenna and makes transport a snap.
All elements are left at their fully assembled length, no break down
required.
With a 10" inch or larger tube the fiberglass mounting tube for the driven
element does not even need to be removed.

K7SAM

ART'S ANTENNA
 

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

ART'S ANTENNA
 

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

up that is similar to mine except I split the coilnumbers by two and
it is still to insensitive so now I have to put a blob of solder in
betwwee the coils to short them until I get the right ratio to suit
the antenna. I like to slow down the swr meter so that I constantly do
not scoot pass the right point

ART'S ANTENNA
 

"Art Unwin" wrote in message
...
On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

Oh, that little, that's thing is for girls, see
http://w5jgv.com/variometer/variometer.htm
Mike :-)

ART'S ANTENNA
 

On Jul 14, 2:29 pm, "amdx" wrote:
"Art Unwin" wrote in message

...

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

Oh, that little, that's thing is for girls, seehttp://w5jgv.com/variometer/variometer.htm
Mike :-)

That one is at least four times the coil turns needed. The previous
one was at least two times the number of coils need.
And if the wire length used was 1100 feet or so the latter also is
much more than required and can be divided by two again.
The idea is not to put a 1000 feet of wire on the variometer or to use
the radiator beyond the HF bands!

ART'S ANTENNA
 

Frank wrote:

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

A general rule of thumb for electrically small antennas is:
small-broadband-efficient, pick any two. One of the common features of
many small antennas is some lossy component or components which make the
bandwidth acceptable. Of course, this also means lowered efficiency,
often to an extreme extent. But most amateurs are able to measure SWR
and almost none are able to measure efficiency, so the loss fools a lot
of people into thinking the small antenna is performing well. I suspect
the variometer is the "secret ingredient" in this case, and that its
chief function is to provide loss. People duplicating the antenna might
try substituting a non-inductive resistor as a simpler way to achieve
the same result.

This isn't to say that a small inefficient antenna "doesn't work". I've
personally worked over 30 countries with a watt and a half on 40 meters
using simple antennas, and many, many people have done a great deal
better with much lower power. So you can still work a lot of stations
with a 100 watt rig and 1% efficient antenna.

Roy Lewallen, W7EL

ART'S ANTENNA
 

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

2 elements required? What does that mean?

ART'S ANTENNA
 

Art Unwin wrote:

...
2 elements required? What does that mean?

Who knows absolutely?

But, most likely, he means a dipole.

On a full wave monopole with no counterpoise and choking off the outer
braid ... I guess you have "one element" as opposed to "2 elements" (for
example: monopole-with-counterpoise/dipole 1/4 wave, 1/2 wave.)

But then, I am guessing. scratches head

Regards,
JS

ART'S ANTENNA
 

2 elements required? What does that mean?

In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

73,

Frank

ART'S ANTENNA
 

On Jul 14, 7:23 pm, "Frank" wrote:
2 elements required? What does that mean?

In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

73,

Frank

Has not a variometer 2 elements?

ART'S ANTENNA
 

Art Unwin wrote:

...
2 elements required? What does that mean?

There ya' go ... his response.

It appears, what he was saying was/is, you cannot obtain maximum
transfer of power to the antenna with the variometer alone--you must use
a pi/LC/etc. (a capacitance in conjunction with an inductance) ...

I re-read his post, that meaning was implied well--but I could only see
it with hindsight.

JS

ART'S ANTENNA
 

In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

73,

Frank

Has not a variometer 2 elements?

No. A variometer is simply a variable inductor.

I should also have added to the above:
Series L, Shunt L etc. etc.......

Frank

ART'S ANTENNA
 

On Jul 14, 8:36 pm, "Frank" wrote:
In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

73,

Frank

Has not a variometer 2 elements?

No. A variometer is simply a variable inductor.

I should also have added to the above:
Series L, Shunt L etc. etc.......

Frank

Then what I can do is to split the circuit in half of a varometer
and connect one in series with the positive and one in series to the
negative
so I have equal turns added or subtracted of opposite wound and
controlled by the single motor.
Sounds good

ART'S ANTENNA
 

Frank wrote:
2 elements required? What does that mean?

In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

Other combinations can be used, for example, adjusting a transmission
line stub length and position, or a transformer in conjunction with a
reactance. The point is that an impedance has two values, commonly
expressed as R and X or as a magnitude and phase angle, so to achieve a
specific impedance requires two "degrees of freedom" -- that is, two
things which you can adjust and which, in simple terms, don't adjust
exactly the same thing. With only one adjustable element, you can get a
specific R, say, or X, but not both.

Roy Lewallen, W7EL

ART'S ANTENNA
 

Roy Lewallen wrote:
With only one adjustable element, you can get a
specific R, say, or X, but not both.

With only one adjustable element, i.e. ladder-line length,
I get X=0 and 35 R 85 ohms which is close enough to
50 ohms for most of us non-perfectionists.

http://www.w5dxp.com/notuner.htm
--
73, Cecil http://www.w5dxp.com

ART'S ANTENNA
 

Then what I can do is to split the circuit in half of a varometer
and connect one in series with the positive and one in series to the
negative
so I have equal turns added or subtracted of opposite wound and
controlled by the single motor.
Sounds good

Not sure I understand what you mean. Comments by Roy, and
others, noted. All these methods are certainly valid. The first step is to
determine the actual impedance of your load before you attempt
to match it, and then design an appropriate network.
For measurement a vector network analyzer is the best method,
but expensive. The "TAPR" analyzer, by Tentec looks
good at $655. Most of the cheap analyzers are not very
accurate, and VSWR is not very useful.

The Smith Chart; provided by Dellsperger, at:
http://www.fritz.dellsperger.net/ is an excellent (free) tool for
matching network design. Also Chris Bowick's
"RF Circuit Design" (At Amazon.com) provides an
insight in the use of the Smith Chart.

Experimentation by variable: series L, shunt C, or shunt C, series L,
could provied a reasonable match. Others probably
have some practical idea.

73,

Frank

ART'S ANTENNA
 

On Jul 15, 2:44 pm, "Frank" wrote:
Then what I can do is to split the circuit in half of a varometer
and connect one in series with the positive and one in series to the
negative
so I have equal turns added or subtracted of opposite wound and
controlled by the single motor.
Sounds good

Not sure I understand what you mean. Comments by Roy, and
others, noted. All these methods are certainly valid. The first step is to
determine the actual impedance of your load before you attempt
to match it, and then design an appropriate network.
For measurement a vector network analyzer is the best method,
but expensive. The "TAPR" analyzer, by Tentec looks
good at $655. Most of the cheap analyzers are not very
accurate, and VSWR is not very useful.

The Smith Chart; provided by Dellsperger, at:http://www.fritz.dellsperger.net/is an excellent (free) tool for
matching network design. Also Chris Bowick's
"RF Circuit Design" (At Amazon.com) provides an
insight in the use of the Smith Chart.

Experimentation by variable: series L, shunt C, or shunt C, series L,
could provied a reasonable match. Others probably
have some practical idea.

73,

Frank

Yes Frank I for some reason found myself settlled on 50 0hms impedance
and I can'r remember why and I didn't make a note of it.
In retrospect I should be looking at around 200 plus or minus! This
should not change to repetitiveness of resonances which is of
importance
for all frequency coverage.
So I am going back to the 100 ohm and upwards that I started with and
first check on sw BC and then fine tune on transmit.
I also checked back on the programming and got somewhere near your
figures tho in practicality my measured impedance
were way higher. I suspect the twisting of wires is the culprit for
the differences
Regards
Art
Regards
Art

ART'S ANTENNA
 

On Jul 14, 3:10 am, derek wrote:
On Jul 14, 8:16 am, Art Unwin wrote

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

If he hasn't got a variometer he can use his tuner as a substitute.
The SWR meter he is using is referenced to 50 ohms so his readings are
false.
When using twisted wire the impedance will go very much higher than
untwisted wire
at least one hundred times . The impedance of his antenna is probably
around the 300 ohm mark so he should
add a 6 or 9 to one transformer. As a furthur adjustment he can put
the up and down wires in parallell such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly. So there are
options available which the ham can chose as well as changing
connections from series to parallel as well as the diferent places he
can add his tuner in the circuit. If he stands the wire tube antenna
upright say as a lamp shade so it appears unobstrusive the radiation
will be omni radial or partialy direcftional if he tilts it and if it
is low power DX that is his hobby then the lower lobe is at least half
of that of a yagi which in his circumstances it should be ideal.Since
the wire is close wound I am not sure of the power limitations but
with it being Hi Temp magnet wire with circuitry of a wavelength I
really don't see a guy in a nursing home having a problem
One thing I am not sure of is the nearnes of the point radiation
antenna with respect to personal health so he may well want to place
it outside say as a frost protector for a rose bush or the like
Regards
Art

ART'S ANTENNA
 

On Jul 15, 7:18 pm, Art Unwin wrote:
On Jul 14, 3:10 am, derek wrote:

On Jul 14, 8:16 am, Art Unwin wrote

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

If he hasn't got a variometer he can use his tuner as a substitute.
The SWR meter he is using is referenced to 50 ohms so his readings are
false.
When using twisted wire the impedance will go very much higher than
untwisted wire
at least one hundred times . The impedance of his antenna is probably
around the 300 ohm mark so he should
add a 6 or 9 to one transformer. As a furthur adjustment he can put
the up and down wires in parallell such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly. So there are
options available which the ham can chose as well as changing
connections from series to parallel as well as the diferent places he
can add his tuner in the circuit. If he stands the wire tube antenna
upright say as a lamp shade so it appears unobstrusive the radiation
will be omni radial or partialy direcftional if he tilts it and if it
is low power DX that is his hobby then the lower lobe is at least half
of that of a yagi which in his circumstances it should be ideal.Since
the wire is close wound I am not sure of the power limitations but
with it being Hi Temp magnet wire with circuitry of a wavelength I
really don't see a guy in a nursing home having a problem
One thing I am not sure of is the nearnes of the point radiation
antenna with respect to personal health so he may well want to place
it outside say as a frost protector for a rose bush or the like
Regards
Art

On the suject of transformers. In the US somebody makes a pre packaged
transformer with five female coax conections depending on the ratio
required,
Since the frequency span is so large as well various locations it may
be that his ratio will land between 6 and 9 to 1
He may want to have ratios that are not as course. What he can do is
to have two rotating contacts ie minuits and hours instead of the
single one provided
On the female conectors you place a cent or copper disk in the centre
which is your contact The rotary cam that moves the contact around is
a 5 pointed star cam with slots from each point towards the center.
The outside of the star surface moves a pin around a fifth of the way
which is the distance between coax connector. So the switch does not
just float across the contact the pin which runs on the cam goes down
and up each slot which provides a stop of rotary motionwhile the
contact is made. I would not make this until the situation proves that
you need it but it does supply matches to with one ohm or so for the
intervening distance beteen 6 and 9 to one. One last thing , If power
is to be used by others on top band it is adviseable to gang two
toroids in parallel
to avoid saturation of the toroidal material. I added the above incase
other club members decide to copy with more favourable operating
conditions
Art
unwinantennas.com/

ART'S ANTENNA
 

On Sun, 13 Jul 2008 13:48:52 -0700 (PDT), derek
wrote:

he took some swr readings they were as follows.

SWR
1.8 = 1.2 :1
3.75 = 1 :1
7.075 = 1.7 :1
14.075 = 4 :1
21.075 = 6 :1

On Tue, 15 Jul 2008 17:18:22 -0700 (PDT), Art Unwin
wrote:

The SWR meter he is using is referenced to 50 ohms so his readings are
false.

What a curious indictment of this design. When it "works" (built to
the authur's specification too) it is a false antenna.

Of course, there are any number of oddities struggling for oxygen in
this goldfish bowl.

he can put the up and down wires in parallell
and it thus fails:
1. to be the loop Guss designed;
2. to be in equilibrium.
such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly.
Equilibrium demands 1 wavelength, but the authur allows up to 100%
error. Pretty loose equilibrium there.

So what does equilibrium mean when both a loop of 1100 feet (not a
wavelength at 160M) and half that, 550 feet (not a wavelength at 160M)
are prescribed simultaneously?

When a half-wave, thin-wire dipole is called for, millions of radio
operators for 3 centuries understood that to be 95% of 262 feet
(accounting for end effect). A full wave loop was similarly closer to
525 feet than 1100 feet.

The oddities abound, but those above are enough to ignite a bonfire of
the vanities.

73's
Richard Clark, KB7QHC

ART'S ANTENNA
 

Art Unwin wrote:


On the suject of transformers. In the US somebody makes a pre packaged
transformer with five female coax conections depending on the ratio
required,

How could you consider using anything from the US! What is wrong with
you?! Everything from the US is CRAP! Especially! Anything!
Associated! With! RF!

What in the SEVEN HELLS are you thinking?!

tom
K0TAR

ART'S ANTENNA
 

Tom Ring wrote:

...
How could you consider using anything from the US! What is wrong with
you?! Everything from the US is CRAP! Especially! Anything!
Associated! With! RF!

What in the SEVEN HELLS are you thinking?!

tom
K0TAR

That argument may well be true. Can you name something made in the USA
so I could check it out?

Mostly, I am aware of things with American names, but made in other
countries. Sometimes, you I might be fortunate, enough, to find
something assembled in America--with parts made in other countries.

Like I say, the world looks like walmart, to me--nothing in walmart
(mostly!) has had an American hand in its' manufacture--only its
marketing and retail to Americans ... the actual money is going to
another nation.

Regards,
JS

ART'S ANTENNA
 

John Smith wrote:
.... Sometimes, you I might be fortunate, enough, to find ...
...

Change that to:

Sometimes, you OR I might be fortunate, enough, to find ...

Ignore the other mistakes, also ...

Regards,
JS

ART'S ANTENNA
 

On Jul 15, 7:18*pm, Art Unwin wrote:
and if it
is low power DX that is his hobby

I suspect he is Sierra Oscar Lima. :(

ART'S ANTENNA
 

John Smith wrote:
"That argument may be true. Could you name something made in the USA so
I could check it out?"

You may not want to check out with it. I bought a field-effect Heathkit
dipper at a hamfest and it needed a 9-volt battery. Fry`s Electronics
was having a made in USA Energizer battery sale so I bought a 9V
two-pack for $5.89. Next time I`ll buy Panasonic or Sony batteries at
the 99-Cent Store.

Best regards, Richard Harrison, KB5WZI