"Wes" wrote in message
ups.com...
On Feb 4, 2:35 pm, "Yuri Blanarovich" wrote:
[snip]

Tony,
by using hairpin matching, you take out portion of the highest current on
the element and fold it into the hairpin where it is taken out of antenna
"participation" for the price of match.

You're kidding right?

Disclosu I use a hairpin (beta) match on my HB Yagi.


In that case I must be :-)

Can you elaborate why would I be kidding?

As far as I know:

If you use hair pin inserted in the middle of the element, you get the
shorter physical length of the element - smaller high current carrying
length.
Half wave resonant element has maximum current in the center, by folding
portion of that element into a hair pin we take that portion "out of the
picture". Just like a loading coil at the base of the vertical - current
drop along the coil.

Hairpin is usually folded back on the boom, 90 deg. to radiator, with any
current left, not participating in the plane of the elements.

Hairpin loading stubs were proven to be worse loading elements than good
quality coils.

You would be better off by inserting coil at the feedpoint instead of (Beta
match) hairpin, or use Delta match, or offset feeding at the 50 ohm pointas
mentioned before.

We might be splitting hairs here, but I hate to lose even fraction of dB if
there is a better way.

I know Beta match works, I used it in some antennas (don't like Gamma
matches), even made a QSO with a ligthbulb as an antenna. It's all relative.
Contesters like to chase every fraction of a dB lost, soon they can add up
to some noticeable real dBs.

YMMV

73 Yuri, K3BU

On Feb 5, 7:59 am, "Yuri Blanarovich" wrote:
"Wes" wrote in message

ups.com...

On Feb 4, 2:35 pm, "Yuri Blanarovich" wrote:
[snip]

Tony,
by using hairpin matching, you take out portion of the highest current on
the element and fold it into the hairpin where it is taken out of antenna
"participation" for the price of match.

You're kidding right?

Disclosu I use a hairpin (beta) match on my HB Yagi.

In that case I must be :-)

Can you elaborate why would I be kidding?

As far as I know:

If you use hair pin inserted in the middle of the element, you get the
shorter physical length of the element - smaller high current carrying
length.

I believe that your first problem is that you are considering the
hairpin (Beta) to be part of the radiator instead of considering the
actual case; it's part of the matching network.


Half wave resonant element has maximum current in the center, by folding
portion of that element into a hair pin we take that portion "out of the
picture". Just like a loading coil at the base of the vertical - current
drop along the coil.

op cit. I'm not "folding a portion of the element." If you subscribe
to the idea that part of the antenna can be "folded into" the feeder
and that by selecting the right feeder length you can "lengthen the
antenna" (as shown in a lot of old ARRL literature) then I have a new
limited space antenna for you. It's a one foot long radiator with a
variable length feeder (a la Cecil) that "makes up" the missing
antenna length.


Hairpin is usually folded back on the boom, 90 deg. to radiator, with any
current left, not participating in the plane of the elements.

If I placed a discrete (lumped element) L-network at the feedpoint the
current in it would not be "participating" either.


Hairpin loading stubs were proven to be worse loading elements than good
quality coils.

When, where, by whom, etc? Oh, BTW, did I mention "THE HAIRPIN IS NOT
A LOADING ELEMENT. It's the inductance in an LC L-network.


You would be better off by inserting coil at the feedpoint instead of (Beta
match) hairpin, or use Delta match, or offset feeding at the 50 ohm pointas
mentioned before.

Why? The hairpin will handle all the power an amateur can supply, it
can (does in my case) form an integral balun and it DC grounds the
element.


We might be splitting hairs here, but I hate to lose even fraction of dB if
there is a better way.

No gain is lost. I can model my Yagi with and without the Beta,
resonating the antenna without it by lengthening the element and the
gain remains the same within 0.01 dB.


I know Beta match works, I used it in some antennas (don't like Gamma
matches), even made a QSO with a ligthbulb as an antenna. It's all relative.
Contesters like to chase every fraction of a dB lost, soon they can add up
to some noticeable real dBs.

I've been a moonbouncer, I know all about fractions of a dB.

"Wes" wrote in message
oups.com...
On Feb 5, 7:59 am, "Yuri Blanarovich" wrote:
"Wes" wrote in message

ups.com...

On Feb 4, 2:35 pm, "Yuri Blanarovich" wrote:
[snip]

Tony,
by using hairpin matching, you take out portion of the highest current
on
the element and fold it into the hairpin where it is taken out of
antenna
"participation" for the price of match.

You're kidding right?

Disclosu I use a hairpin (beta) match on my HB Yagi.

In that case I must be :-)

Can you elaborate why would I be kidding?

As far as I know:

If you use hair pin inserted in the middle of the element, you get the
shorter physical length of the element - smaller high current carrying
length.

I believe that your first problem is that you are considering the
hairpin (Beta) to be part of the radiator instead of considering the
actual case; it's part of the matching network.


Do you have to shorten the (driven) element if you insert the hairpin in the
middle or not (to maintain the resonant frequency)? Telrex 40m Yagis did use
hairpins at the center of the element as a loading and shortening the
element length. To me that is the matching network too, but at the expenses
of shortening the element length - center loading, similar to base loading
the resonant quarter wave vertical.


Half wave resonant element has maximum current in the center, by folding
portion of that element into a hair pin we take that portion "out of the
picture". Just like a loading coil at the base of the vertical - current
drop along the coil.

op cit. I'm not "folding a portion of the element." If you subscribe
to the idea that part of the antenna can be "folded into" the feeder
and that by selecting the right feeder length you can "lengthen the
antenna" (as shown in a lot of old ARRL literature) then I have a new
limited space antenna for you. It's a one foot long radiator with a
variable length feeder (a la Cecil) that "makes up" the missing
antenna length.


You fold the portion of the element, it's called loading, at the base, in
the middle or anywhere along the element length. The folded hairpin has
inductance, just like a coil, and can be replaced with the coil of similar
inductance. The loading element is not the limited space antenna, look at
the currents at its ends and see the difference in curent distribution along
it and how it participates in the overall radiator current distribution and
corresponding area under the cosine curve representative of the efficiency.
We are back to the loading coil "problem" and that's why we pointed out the
efect and its impact on the antenna performance.


Hairpin is usually folded back on the boom, 90 deg. to radiator, with any
current left, not participating in the plane of the elements.

If I placed a discrete (lumped element) L-network at the feedpoint the
current in it would not be "participating" either.


Not much, but help with cleaner pattern.


Hairpin loading stubs were proven to be worse loading elements than good
quality coils.

When, where, by whom, etc? Oh, BTW, did I mention "THE HAIRPIN IS NOT
A LOADING ELEMENT. It's the inductance in an LC L-network.


Here we go again? We are talking about standing wave circuit - antenna
radiator or element. So inductance is not a loading element? As far as I
know inductance (coil, hairpin) or capacitance (top hat, L, T loading) are
used as a loading elements to shorten the physical length of the antenna
element, while maintaining electrical length.
There was an article by W6?? in CQ and other examples when they replaced
hairpin loading on Yagi elements with coils and got significant improvement
in the performance of KLM 3 el 80 Yagi, better gain, much better pattern due
to less interference of the folded back hairpin with the element.
Measurements and modeling before and after showed that.


pointas
mentioned before.

Why? The hairpin will handle all the power an amateur can supply, it
can (does in my case) form an integral balun and it DC grounds the
element.


No argument here, you can do that with coil and gain some edge.

We might be splitting hairs here, but I hate to lose even fraction of dB
if
there is a better way.

No gain is lost. I can model my Yagi with and without the Beta,
resonating the antenna without it by lengthening the element and the
gain remains the same within 0.01 dB.


No gain lost would be 0.0000 dB :-)


I know Beta match works, I used it in some antennas (don't like Gamma
matches), even made a QSO with a ligthbulb as an antenna. It's all
relative.
Contesters like to chase every fraction of a dB lost, soon they can add
up
to some noticeable real dBs.

I've been a moonbouncer, I know all about fractions of a dB.

Then you should appreciate the above.

73 Yuri, K3BU

This will be the last word I have on this topic.

I have placed two files he

www.k6mhe.com/n7ws/N7WS_Yagi_Resonant.EZ

and he

www.k6mhe.com/n7ws/N7WS_Yagi_Shortened.EZ

The files are models of my 20-meter three-element Yagi that are as
nearly representative of the physical antenna and its location as I
can make them. The only difference between them is the half-length of
the DE. The actual antenna uses the shortened version with a stub
(Beta) matching/balun arrangement.

Two photos of the details of this are he

www.k6mhe.com/n7ws/YagiFeed-1a.jpg

and he

www.k6mhe.com/n7ws/YagiFeed-2a.jpg

The photos were taken with the antenna mounted on the tower and the
tower folded over in case you're wondering about the orientation.

For the purposes of the discussion I have removed the stub matching
system from the model.

The following transformation and matching exercise can be performed
using a Smith Chart, your favorite computer program or with pencil on
the back of an envelope. I happen to prefer, and highly recommend,
AC6LA's XLZIZL.xls Excel workbook for this stuff.

First let's analyze the full-length, resonant DE version. After
running the analysis we (should) have a feedpoint Z of 26.76 +j0 and a
gain at the selected elevation of 12.91 dBi. The SWR is 1.87:1.

Instead of the integral stub, which Yuri believes is part of the
antenna that is "folded back" along the boom, I will move the matching
system away from this location using an ideal ½ wavelength (34.7 foot)
transmission line with an ideal current balun at the antenna end. I
don't believe anyone would argue that the feedpoint impedance is not
replicated exactly at the input end of this line.

At the input end of the lossless line, the Z is of course, 26.76 +j0.
Because, as will be shown, the stub matching system is nothing more
than an L-network; I will use the same at the input of the half-
wavelength line.

I begin by inserting a series capacitor, C = 448 pF and Q = 1000. At
the input side of this capacitor the Z is now: 26.785 -j25.062. If
using XLZIZL, the loss in this capacitor is shown as 0.004 dB, because
Q is not infinite.

Continuing, I place a shunt inductor, L = 0.6, Q = 200 across the
input of the series capacitor. The resulting input Z = 50.00 +j0.2.
The total network loss is 0.02 dB. This is the baseline.

Returning to the shortened driven element version, after analysis, we
find that the input Z = 24.55 -j25.2 and the gain is unchanged at
12.91 dBi. At the input end of our magical ½ wavelength line, the Z
remains 24.55 -j25.2.

Once again using the L-network system, I find that the series
capacitor is unnecessary and I can proceed by adding a shunt
inductance. Rather than using Yuri's "preferred" discrete inductor,
let's use a "lossy" stub. Instead of using the large diameter,
parallel tube stub of the actual antenna, I'll use a standard
transmission line for the stub. XLZIZL has a number if transmission
lines and their parameters "built in," including the Wireman ladder
lines. The parameters for these are those I derived in my ladder line
paper.

http://www.k6mhe.com/n7ws/Ladder_Line.pdf

Selecting Wireman 553, shorting one end and placing the other in
parallel with the input to the lossless line and doing a little
manipulation and I find that a 14.85" length makes the Z = 50.12
+j0.18. The network loss remains 0.02 dB. So much for this less than
ideal stub vs. Yuri's preferred discrete inductor.

There you have it. The stub matching method is equal to a discrete L-
network in efficiency, it does not detract from the antenna efficiency
one bit, it can incorporate the balun function without additional
components, it grounds the feedpoint, with a little sealant on the
cable, it is weatherproof and unlike Gammas and Tee-matches, it will
handle full power without being prone to capacitor breakdown. It is
not part of the radiator; it is part of the matching network. Period.

Wes wrote:
This will be the last word I have on this topic.

I have placed two files he

www.k6mhe.com/n7ws/N7WS_Yagi_Resonant.EZ

and he

www.k6mhe.com/n7ws/N7WS_Yagi_Shortened.EZ

The files are models of my 20-meter three-element Yagi that are as
nearly representative of the physical antenna and its location as I
can make them. The only difference between them is the half-length of
the DE. The actual antenna uses the shortened version with a stub
(Beta) matching/balun arrangement.

Two photos of the details of this are he

www.k6mhe.com/n7ws/YagiFeed-1a.jpg

and he

www.k6mhe.com/n7ws/YagiFeed-2a.jpg

The photos were taken with the antenna mounted on the tower and the
tower folded over in case you're wondering about the orientation.

For the purposes of the discussion I have removed the stub matching
system from the model.

The following transformation and matching exercise can be performed
using a Smith Chart, your favorite computer program or with pencil on
the back of an envelope. I happen to prefer, and highly recommend,
AC6LA's XLZIZL.xls Excel workbook for this stuff.

First let's analyze the full-length, resonant DE version. After
running the analysis we (should) have a feedpoint Z of 26.76 +j0 and a
gain at the selected elevation of 12.91 dBi. The SWR is 1.87:1.

Instead of the integral stub, which Yuri believes is part of the
antenna that is "folded back" along the boom, I will move the matching
system away from this location using an ideal ½ wavelength (34.7 foot)
transmission line with an ideal current balun at the antenna end. I
don't believe anyone would argue that the feedpoint impedance is not
replicated exactly at the input end of this line.

At the input end of the lossless line, the Z is of course, 26.76 +j0.
Because, as will be shown, the stub matching system is nothing more
than an L-network; I will use the same at the input of the half-
wavelength line.

I begin by inserting a series capacitor, C = 448 pF and Q = 1000. At
the input side of this capacitor the Z is now: 26.785 -j25.062. If
using XLZIZL, the loss in this capacitor is shown as 0.004 dB, because
Q is not infinite.

Continuing, I place a shunt inductor, L = 0.6, Q = 200 across the
input of the series capacitor. The resulting input Z = 50.00 +j0.2.
The total network loss is 0.02 dB. This is the baseline.

Returning to the shortened driven element version, after analysis, we
find that the input Z = 24.55 -j25.2 and the gain is unchanged at
12.91 dBi. At the input end of our magical ½ wavelength line, the Z
remains 24.55 -j25.2.

Once again using the L-network system, I find that the series
capacitor is unnecessary and I can proceed by adding a shunt
inductance. Rather than using Yuri's "preferred" discrete inductor,
let's use a "lossy" stub. Instead of using the large diameter,
parallel tube stub of the actual antenna, I'll use a standard
transmission line for the stub. XLZIZL has a number if transmission
lines and their parameters "built in," including the Wireman ladder
lines. The parameters for these are those I derived in my ladder line
paper.

http://www.k6mhe.com/n7ws/Ladder_Line.pdf

Selecting Wireman 553, shorting one end and placing the other in
parallel with the input to the lossless line and doing a little
manipulation and I find that a 14.85" length makes the Z = 50.12
+j0.18. The network loss remains 0.02 dB. So much for this less than
ideal stub vs. Yuri's preferred discrete inductor.

There you have it. The stub matching method is equal to a discrete L-
network in efficiency, it does not detract from the antenna efficiency
one bit, it can incorporate the balun function without additional
components, it grounds the feedpoint, with a little sealant on the
cable, it is weatherproof and unlike Gammas and Tee-matches, it will
handle full power without being prone to capacitor breakdown. It is
not part of the radiator; it is part of the matching network. Period.

Hi Wes,

A very interesting design and discussion. Thank you for posting it.

I could be wrong but I think Yuri's main point was that if [fill in
the blank] loading unit radiates at right angles to the beam pattern
(or out of phase with it) it detracts from the gain of the antenna. I
think that's probably a reasonable claim.

73, ac6xg

"Wes" wrote in message
ups.com...
This will be the last word I have on this topic.

As: This is the last word from the higher authority, like, no more
arguments, I am right, case closed? Just in case you might be wrong, here
we go:-)


I have placed two files he
www.k6mhe.com/n7ws/N7WS_Yagi_Resonant.EZ
and he
www.k6mhe.com/n7ws/N7WS_Yagi_Shortened.EZ
The files are models of my 20-meter three-element Yagi that are as
nearly representative of the physical antenna and its location as I
can make them. The only difference between them is the half-length of
the DE. The actual antenna uses the shortened version with a stub
(Beta) matching/balun arrangement.

What you mean half length of DE?
Resonant DE is 410.68" long
Shortened DE is 399.64" long - that is 11.04" difference
Resonant frequency on resonant model is 14.18 and shortened is 14.48


Instead of the integral stub, which Yuri believes is part of the
antenna that is "folded back" along the boom, I will move the matching
system away from this location using an ideal ½ wavelength (34.7 foot)
transmission line with an ideal current balun at the antenna end. I
don't believe anyone would argue that the feedpoint impedance is not
replicated exactly at the input end of this line.

Yuri believes? Is anyone there who does not believe that hairpin loading
stub or beta match stub inserted in the middle of driven element is not the
part of the element, aka, standing wave resonant circuit? Like there is no
RF current flowing into the hairpin? Like element does not have to be
shortened to compensate for the insertion of the stub? Doesn't Yagi antenna
work with half wave (+-) resonant elements? If you loaded, inserted stubs in
the parasitic elements, you would not have to shorten them?

"Calculations" proving ??? snipped

The network loss remains 0.02 dB. So much for this less than
ideal stub vs. Yuri's preferred discrete inductor.

There you have it. The stub matching method is equal to a discrete L-
network in efficiency, it does not detract from the antenna efficiency
one bit, it can incorporate the balun function without additional
components, it grounds the feedpoint, with a little sealant on the
cable, it is weatherproof and unlike Gammas and Tee-matches, it will
handle full power without being prone to capacitor breakdown. It is
not part of the radiator; it is part of the matching network. Period.

Claiming that beta match or hairpin loading inductance is not the part of
the radiator is news to me.
Claiming that driven element was shortened to half, when in fact just by 11"
and resonant frequency moved from abt 14.18 to 14.48 MHz, and modeling the
antenna without the beta match hair pin, and then "calculating" 0.02 dB
difference in gain, sure "proves" the point.

Here I described the real life situation and modeling by using simple case
of 40m dipole, resonant and resonant shortened with "beta match" hairpin. I
maintain the resonant frequency and compensate for the effects of inserting
the hairpin. The gain on the dipole drops by 0.15 dB when fed at the 75 ohm
point and by 0.2 dB when fed close to 50 ohm point. You can read the rest at
my web site:
http://www.k3bu.us/beta_match.htm

Again, it has ben proven by modeling and in practice that loading solenoid
coils are better performers as loading element than hairpins, especially
when better symetry along the element is important for bettern pattern and
F/B. But I guess, that's another story to argue.

Not the last word from me, if I am wrong and made error in modeling, I would
like to be corrected. (I tried to post the EZNEC files, but having problem
downloading them. Will try to rectify.)

73 Yuri, K3BU.us

On Feb 10, 7:27 pm, "Yuri Blanarovich" wrote:

My previous ISP sold me off to a new one. SInce that time I've had no
end of email problems and in addition the new guys don't provide
newsgroups, so I've been reduced to using Google Groups. Yuch.

I spent too much time composing a response to Yuri's last post and
then did not see it appear after posting. I will not waste further
time, but in a nutshell I offered another case using the self-
reactance of the DE as part of the matching network.

In this example, to avoid any "loss due to loading" resulting from
shortening the DE, I *lengthen* the DE to obtain an inductive
reactance for the series arm of an L-network and then use a shunt
capacitor for the second matching element.

The model is he

http://www.k6mhe.com/n7ws/N7WS_Yagi_Lengthened.EZ

Run the analysis, and add a shunt 195 pF and see what you get.

Regards,

Wes N7WS

Looks like W8JI type of response: I am right, I will not respond to
questions and arguments and my is last word!"

Fact 1. - When hairpin or beta match is inserted in the driven element or
any resonant half wave dipole, it has current flowing through it.

Fact 2. That element has to be shortened if resonance is to be maintained,
which means that it is a center inductive loading element, hairpin, beta
match is the part of the antenna standing wave circuit.

Fact 3. There is current that would more, less belong to the antenna element
flowing in the hairpin, folded on itself and on right angle to driven
element, not contributing to overall current distribution. That can be seen
in my EZNEC model in the article. That portion of the current is not in line
with the rest of the element, it is missing from as to compared to full size
element and therefore efficiency is slightly lower (middle part of the
cosine wave is "missing" folded with hairpin). On typical 40m dipole, as I
modeled, it accounts for about 0.2 dB loss.

The original argument was is the beta match lossy or not.
My modeling of the real situation is ignored, also findings and experimental
verification of others who replaced hairpins with solenoid coils is ignored.
What you are "arguing" is that if you place the matching network in the
driven element (now you even lengthen it) that there is no loss.
http://www.k3bu.us/beta_match.htm
Is my modeling of 40m dipole wrong? Where? On dipole it shows about 0.2 dB
loss, which gets bit more when used in multielement array.

If you are denying that there is a RF antenna current flowing in the Beta
match hairpin, then you are denying reality and I rest my case. No point of
arguing or discussing when you do not show where I am wrong, but you offer
"proof" by juggling matching components at the feedpoint. We are talking
about hairpin that is part of the antenna element, has current flowing in
the system and it has feedline attached at the feedpoint of element and
hairpin. No tricks with coils or capacitors inserted half wave somewhere.

73 Yuri, K3BU.us

We are not arguing loss due to loading, we are arguing - does hairpin beta
match contribute to the loss in the system or not.
I mentioned that there are better alternatives, if one choses to be less
lossy.


"Wes" wrote in message
oups.com...
On Feb 10, 7:27 pm, "Yuri Blanarovich" wrote:

My previous ISP sold me off to a new one. SInce that time I've had no
end of email problems and in addition the new guys don't provide
newsgroups, so I've been reduced to using Google Groups. Yuch.

I spent too much time composing a response to Yuri's last post and
then did not see it appear after posting. I will not waste further
time, but in a nutshell I offered another case using the self-
reactance of the DE as part of the matching network.

In this example, to avoid any "loss due to loading" resulting from
shortening the DE, I *lengthen* the DE to obtain an inductive
reactance for the series arm of an L-network and then use a shunt
capacitor for the second matching element.

The model is he

http://www.k6mhe.com/n7ws/N7WS_Yagi_Lengthened.EZ

Run the analysis, and add a shunt 195 pF and see what you get.

Regards,

Wes N7WS

Wes wrote:
op cit. I'm not "folding a portion of the element." If you subscribe
to the idea that part of the antenna can be "folded into" the feeder
and that by selecting the right feeder length you can "lengthen the
antenna" (as shown in a lot of old ARRL literature) then I have a new
limited space antenna for you. It's a one foot long radiator with a
variable length feeder (a la Cecil) that "makes up" the missing
antenna length.

Why didn't I think of that? The SWR on the ladder line on 40m
would only be 47,000,000:1 and the feedpoint impedance would
be 10 micro-ohms at system resonance.
--
73, Cecil http://www.w5dxp.com