Constructional details
 

In the picture below appears the geometry of the Hentenna.
No constructional details are given.

http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the connector.
Because of the skin effect there is current in the interior and the exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma

(I assume "a" in the diagram you linked to is the wire radius or
diameter, though it probably is not critical.)

Yes, it appears that it would be best if the feed is balanced. A
balun to transform from an unbalanced feed to a balanced one is a good
idea for this antenna. You can put the balun at the antenna, or some
distance away and feed from the balun to the antenna with balanced
line, if the line is arranged symmetrically with respect to the
antenna. It would also be good to know the approximate feedpoint
impedance of the antenna. An eznec (or similar) model of the antenna
should give you an idea about the feedpoint impedance. If you use
coaxial feedline to the balun, which connects in turn directly to the
antenna, and if you dress the feedline so it runs away from the
antenna perpendicular to the wire where the feed point is, a single
balun is likely enough, but if the feedline runs away from the antenna
at an angle, it may be advisable to also use a choke-type balun
perhaps 1/4 wavelength from the feedpoint. On the other hand, I would
not expect enough gain from this antenna that it would matter a lot,
and you may do fine not using a balun at all and just letting the
feedline radiate a little.

Cheers,
Tom

"emma" wrote in message ...
In the picture below appears the geometry of the Hentenna.
No constructional details are given.

http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the connector.
Because of the skin effect there is current in the interior and the exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma

Yes,"a" in the diagram below is the wire radius.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

My design results, for two different radius values,
of R, X, Z, Rho, SWR and Directivity, as they vary with the driving element
position,
are shown at

http://antennas.ee.duth.gr/recradioa...ntennaA/Henten
naA.htm

and

http://antennas.ee.duth.gr/recradioa...ntennaB/Henten
naB.htm

I would be most grateful if you could have a look at these results and make
any comments.

I would also appreciate any reference you may point at, in addition to those
I collected at

http://antennas.ee.duth.gr/recradioa...ferences/refer
ences.htm

Thank you in advance for your time,

Emma





"Tom Bruhns" wrote in message
m...
(I assume "a" in the diagram you linked to is the wire radius or
diameter, though it probably is not critical.)

Yes, it appears that it would be best if the feed is balanced. A
balun to transform from an unbalanced feed to a balanced one is a good
idea for this antenna. You can put the balun at the antenna, or some
distance away and feed from the balun to the antenna with balanced
line, if the line is arranged symmetrically with respect to the
antenna. It would also be good to know the approximate feedpoint
impedance of the antenna. An eznec (or similar) model of the antenna
should give you an idea about the feedpoint impedance. If you use
coaxial feedline to the balun, which connects in turn directly to the
antenna, and if you dress the feedline so it runs away from the
antenna perpendicular to the wire where the feed point is, a single
balun is likely enough, but if the feedline runs away from the antenna
at an angle, it may be advisable to also use a choke-type balun
perhaps 1/4 wavelength from the feedpoint. On the other hand, I would
not expect enough gain from this antenna that it would matter a lot,
and you may do fine not using a balun at all and just letting the
feedline radiate a little.

Cheers,
Tom

"emma" wrote in message
...
In the picture below appears the geometry of the Hentenna.
No constructional details are given.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the
connector.
Because of the skin effect there is current in the interior and the
exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of
two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma

Yes,"a" in the diagram below is the wire radius.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

My design results, for two different radius values,
of R, X, Z, Rho, SWR and Directivity, as they vary with the driving element
position,
are shown at

http://antennas.ee.duth.gr/recradioa...ntennaA/Henten
naA.htm

and

http://antennas.ee.duth.gr/recradioa...ntennaB/Henten
naB.htm

I would be most grateful if you could have a look at these results and make
any comments.

I would also appreciate any reference you may point at, in addition to those
I collected at

http://antennas.ee.duth.gr/recradioa...ferences/refer
ences.htm

Thank you in advance for your time,

Emma



"Tom Bruhns" wrote in message
m...
(I assume "a" in the diagram you linked to is the wire radius or
diameter, though it probably is not critical.)

Yes, it appears that it would be best if the feed is balanced. A
balun to transform from an unbalanced feed to a balanced one is a good
idea for this antenna. You can put the balun at the antenna, or some
distance away and feed from the balun to the antenna with balanced
line, if the line is arranged symmetrically with respect to the
antenna. It would also be good to know the approximate feedpoint
impedance of the antenna. An eznec (or similar) model of the antenna
should give you an idea about the feedpoint impedance. If you use
coaxial feedline to the balun, which connects in turn directly to the
antenna, and if you dress the feedline so it runs away from the
antenna perpendicular to the wire where the feed point is, a single
balun is likely enough, but if the feedline runs away from the antenna
at an angle, it may be advisable to also use a choke-type balun
perhaps 1/4 wavelength from the feedpoint. On the other hand, I would
not expect enough gain from this antenna that it would matter a lot,
and you may do fine not using a balun at all and just letting the
feedline radiate a little.

Cheers,
Tom

"emma" wrote in message
...
In the picture below appears the geometry of the Hentenna.
No constructional details are given.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the
connector.
Because of the skin effect there is current in the interior and the
exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of
two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma

Hi Emma,

I don't have many comments, only that the increased bandwidth you see
in your model with the larger wire is consistent with what I'd expect,
and that it surprises me a little that the resistive part of the
feedpoint impedance is monotonic with "d" in the thin-wire case but
not in the thicker-wire case.

Also, I see antenna design as a series of tradeoffs which can be
divided into a few areas: arrange conductors so that you can get
current distributions give you the directional pattern you want and
also in an arrangement that you can build with sufficient mechanical
ruggedness and in a suitable mechanical configuration for your
application. Arrange a feed and matching system so you can get the
desired current distribution on the conductors. Decouple your
feedline and any other conductors in the area from the antenna
structure. The tradeoffs come when you find there is no practical way
to feed your ideal antenna, or when you find it's too big to mount on
your car, or whatever. The antenna you've modeled doesn't seem very
difficult to build, so I would suggest actually building one and
testing it to see if it works like you expect, and if it's
mechanically practical for you. These are pretty generic comments,
but I'm honestly not very clear on just what you wish to
accomplish--what problem you are trying to solve.

Cheers,
Tom


"Emma" wrote in message ...
Yes,"a" in the diagram below is the wire radius.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

My design results, for two different radius values,
of R, X, Z, Rho, SWR and Directivity, as they vary with the driving element
position,
are shown at

http://antennas.ee.duth.gr/recradioa...ntennaA/Henten
naA.htm

and

http://antennas.ee.duth.gr/recradioa...ntennaB/Henten
naB.htm

I would be most grateful if you could have a look at these results and make
any comments.

I would also appreciate any reference you may point at, in addition to those
I collected at

http://antennas.ee.duth.gr/recradioa...ferences/refer
ences.htm

Thank you in advance for your time,

Emma

Tom,

thank you for your comments.
I will try to make it more clear.
These are some results I arrived at before
I start its construction and carry out the measurements.
Firstly, my aim was to find the exact place of the driven-element
where the SWR is lowest.
I used RICHWIRE for my simulation.This program has an upper limit
for the wire radius.So I had to make two categories of diagams,
one for wire radius 0.00037 [wl], which is rather not realizable,
and one for 0.0037 [wl] ignoring the programs criteria.
I ended up that the Hentenna is unfortunately a narrow band antenna.
So it would be rather difficult to build it.
What I am working on now, is changing the antennas dimensions
so that I would come to an even lower SWR and a broader bandwidth.

Emma




"Emma" wrote in message ...
Yes,"a" in the diagram below is the wire radius.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

My design results, for two different radius values,
of R, X, Z, Rho, SWR and Directivity, as they vary with the driving element
position,
are shown at

http://antennas.ee.duth.gr/recradioa...ntennaA/Henten
naA.htm

and

http://antennas.ee.duth.gr/recradioa...ntennaB/Henten
naB.htm

I would be most grateful if you could have a look at these results and make
any comments.

I would also appreciate any reference you may point at, in addition to those
I collected at

http://antennas.ee.duth.gr/recradioa...ferences/refer
ences.htm

Thank you in advance for your time,

Emma



"Tom Bruhns" wrote in message
m...
(I assume "a" in the diagram you linked to is the wire radius or
diameter, though it probably is not critical.)

Yes, it appears that it would be best if the feed is balanced. A
balun to transform from an unbalanced feed to a balanced one is a good
idea for this antenna. You can put the balun at the antenna, or some
distance away and feed from the balun to the antenna with balanced
line, if the line is arranged symmetrically with respect to the
antenna. It would also be good to know the approximate feedpoint
impedance of the antenna. An eznec (or similar) model of the antenna
should give you an idea about the feedpoint impedance. If you use
coaxial feedline to the balun, which connects in turn directly to the
antenna, and if you dress the feedline so it runs away from the
antenna perpendicular to the wire where the feed point is, a single
balun is likely enough, but if the feedline runs away from the antenna
at an angle, it may be advisable to also use a choke-type balun
perhaps 1/4 wavelength from the feedpoint. On the other hand, I would
not expect enough gain from this antenna that it would matter a lot,
and you may do fine not using a balun at all and just letting the
feedline radiate a little.

Cheers,
Tom

"emma" wrote in message
...
In the picture below appears the geometry of the Hentenna.
No constructional details are given.


http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the
connector.
Because of the skin effect there is current in the interior and the
exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of
two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma

On 20 Nov 2003 06:09:42 -0800, (emma) wrote:

I will try to make it more clear.
These are some results I arrived at before
I start its construction and carry out the measurements.
Firstly, my aim was to find the exact place of the driven-element
where the SWR is lowest.
I used RICHWIRE for my simulation.This program has an upper limit
for the wire radius.So I had to make two categories of diagams,
one for wire radius 0.00037 [wl], which is rather not realizable,
and one for 0.0037 [wl] ignoring the programs criteria.
I ended up that the Hentenna is unfortunately a narrow band antenna.
So it would be rather difficult to build it.
What I am working on now, is changing the antennas dimensions
so that I would come to an even lower SWR and a broader bandwidth.

Emma


Hi Emma,

How do you arrive at the conclusion your (or any) Hentenna is narrow
band? What data supports this? The numerous links you provided
suggest nothing remarkable except gain. In other words, what
bandwidth do you call narrow? Normal? Wide?

To my eye, this design is a shorted stub that is tapped within to find
a match from a continuum of impedances available as a product of its
resonant geometry and the position of the tap. Loss, being
inferentially linked to bandwidth, is a product of bulk conductor
(wire radius for sure). Wire radius certainly impacts resonance vs.
size (and we are back to geometry of resonance to find the Z of
choice).

73's
Richard Clark, KB7QHC

Richard Clark wrote in message . ..
On 20 Nov 2003 06:09:42 -0800, (emma) wrote:

I will try to make it more clear.
These are some results I arrived at before
I start its construction and carry out the measurements.
Firstly, my aim was to find the exact place of the driven-element
where the SWR is lowest.
I used RICHWIRE for my simulation.This program has an upper limit
for the wire radius.So I had to make two categories of diagams,
one for wire radius 0.00037 [wl], which is rather not realizable,
and one for 0.0037 [wl] ignoring the programs criteria.
I ended up that the Hentenna is unfortunately a narrow band antenna.
So it would be rather difficult to build it.
What I am working on now, is changing the antennas dimensions
so that I would come to an even lower SWR and a broader bandwidth.

Emma


Hi Emma,

How do you arrive at the conclusion your (or any) Hentenna is narrow
band? What data supports this? The numerous links you provided
suggest nothing remarkable except gain. In other words, what
bandwidth do you call narrow? Normal? Wide?

To my eye, this design is a shorted stub that is tapped within to find
a match from a continuum of impedances available as a product of its
resonant geometry and the position of the tap. Loss, being
inferentially linked to bandwidth, is a product of bulk conductor
(wire radius for sure). Wire radius certainly impacts resonance vs.
size (and we are back to geometry of resonance to find the Z of
choice).

73's
Richard Clark, KB7QHC


Hi Richard,

I found your comments really interesting.
Firstly, I would like to explain why
I think that the Hentenna is a narrowband antenna.
My design results for SWR vs frequency,
while the antennas dimensions vary,
are shown at

http://antennas.ee.duth.gr/recradioa...q/Hentenna.htm

The table below could also be usefull



BANDWIDTH

50 Ohm 75 Ohm 300 Ohm
H = wl/2 W = wl/4 : - - 14.4 %

H = wl/4 W = wl : - 3.6 % -

H = wl W = wl/4 : - 3.6 % -

H = wl/2 W = wl/6 : 2.7 % 3.6 % -



Moreover, IMHO I don't think that the Hentenna
is a shorted stub .The distance W is
longer than the distance between two transmission
lines.
I would be most grateful if you could make
any more comments.


Emma

On 26 Nov 2003 08:36:52 -0800, (emma) wrote:

Hi Richard,

I found your comments really interesting.
Firstly, I would like to explain why
I think that the Hentenna is a narrowband antenna.
My design results for SWR vs frequency,
while the antennas dimensions vary,
are shown at

http://antennas.ee.duth.gr/recradioa...q/Hentenna.htm

The traces should be separable in their display. In other words, dot
markers for one Z, box markers for the next Z, delta markers for the
last Z and so on.

Further, since you admit dimensions vary, for GHz designs this could
bring a substantial bias in results.

The table below could also be usefull

In the future, please observe newsgroup protocol and use "fixed font"
when aligning text columns of data.

BANDWIDTH

50 Ohm 75 Ohm 300 Ohm
H = wl/2 W = wl/4 : - - 14.4 %

H = wl/4 W = wl : - 3.6 % -

H = wl W = wl/4 : - 3.6 % -

H = wl/2 W = wl/6 : 2.7 % 3.6 % -

Moreover, IMHO I don't think that the Hentenna
is a shorted stub .The distance W is
longer than the distance between two transmission
lines.
I would be most grateful if you could make
any more comments.

Emma

Hi Emma,

A shorted stub it is. A simple look at the geometry is intuitive to
this statement. Resonance provides the logical basis for this
statement. Obviously distances and wire diameter are chosen on the
basis of Z desired. I've done dozens of models of this style, and
variations of it, years ago. I observed then that the characteristic
of "miracle antenna" applied to it now is overstated.

73's
Richard Clark, KB7QHC

Hi Richard,

I tried it. I considered my Hentenna as a transmission line and I
applied the standing wave theory according to "THE ARRL ANTENNA BOOK
18th Ed 1997, Fig 65".
The currents flow the antenna as shown below:

http://antennas.ee.duth.gr/recradioa...ndingwaves.htm


Obviously, the currents of the 3 parallel horizontal branches are
flowing in the same direction. Their sum gives the total field. On the
other hand, we have 3 antiparallel pairs of currents flowing through
the vertical branches. Therefore the field becomes equal to zero.
As a result, the arrangement radiates and it can not be considered as
a transmission line.

Emma.