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Off-Topic: Your advice/suggestion about antenna

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Edward R Cole

Re: Off-Topic: Your advice/suggestion about antenna

OK, well one can study theory for several years before deciding what
antenna to use ... or just put up something and try it.
My guess a quarter-wave vertical with some radials will work. How
well? You will only find out by trying it.

My favorite HF antenna has been the simple half-wave dipole -cheap,
easy, quick. I did eventually obtain a triband trap yagi for
20-15-10m and works much better. Currently I have a 80/40m inverted-V
...and it works well for my needs. Worked a station on 80m SSB with
S9 signals on Saturday at 11am! Sure he was only a hundred+ miles
(short range is often harder). K3/10+KXPA100

On 630m (475-KHz) I have a 43-foot high inverted-L (that is 8% of a
quarter-wave). And my radials are limited to 100-foot by my property
lines. Obviously a very poor antenna. My CW signals was heard 4,000
miles away in Buffalo, NY. Not an everyday occurrence, but a surprise to me.

73, Ed

-----------------------

There is some erroneous information here, as well as in Don W3FPR's post.

Radials, whether buried or raised, only affect near field ground return
currents.? You cannot improve ground conductivity beyond the radials,
and the strength of the low angle lobe is directly affected by the
ground conductivity several wavelengths distant from the vertical.? This
is well established science and you can clearly see the effect in simple
models.

Dave?? AB7E

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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Bob McGraw - K4TAX

Re: Off-Topic: Your advice/suggestion about antenna

Antenna fact: If it stayed up in the last storm, either (a) it was well
built and properly installed, or (b) it wasn't large enough.

Thus, if it works to your satisfaction, then it is a good antenna.

73

Bob, K4TAX

On 3/15/2020 2:37 PM, Edward R Cole wrote:

> OK, well one can study theory for several years before deciding what
> antenna to use ... or just put up something and try it.
> My guess a quarter-wave vertical with some radials will work. How
> well? You will only find out by trying it.
>
> My favorite HF antenna has been the simple half-wave dipole -cheap,
> easy, quick. I did eventually obtain a triband trap yagi for
> 20-15-10m and works much better. Currently I have a 80/40m inverted-V
> ...and it works well for my needs. Worked a station on 80m SSB with
> S9 signals on Saturday at 11am! Sure he was only a hundred+ miles
> (short range is often harder). K3/10+KXPA100
>
> On 630m (475-KHz) I have a 43-foot high inverted-L (that is 8% of a
> quarter-wave). And my radials are limited to 100-foot by my property
> lines. Obviously a very poor antenna. My CW signals was heard 4,000
> miles away in Buffalo, NY. Not an everyday occurrence, but a surprise
> to me.
>
> 73, Ed
>
> -----------------------
>
> There is some erroneous information here, as well as in Don W3FPR's post.
>
> Radials, whether buried or raised, only affect near field ground return
> currents.? You cannot improve ground conductivity beyond the radials,
> and the strength of the low angle lobe is directly affected by the
> ground conductivity several wavelengths distant from the vertical.? This
> is well established science and you can clearly see the effect in simple
> models.
>
> Dave?? AB7E
>
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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David Gilbert

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Edward R Cole

Well, I'm still under the impression that we are members of a
knowledge-based hobby, and being willing to understand the basics of
antennas seems like it fits that description. It doesn't take years of
study to understand the basics ... a bit of reading the ARRL Antenna
Book and a couple hours playing around with EZNEC+ covers that pretty
nicely. Not being dismissive of advice from others who maybe had spent
quite a while trying to understand antenna theory helps as well.

I regularly try out different antennas, some for home use, some for
Field Day, and some for other portable ventures. I model EVERYTHING
before I try to build it and I guarantee it has saved me hours of wasted
effort and lots of dollars of wasted money. I can also categorically
state that I have learned FAR more about antennas from modeling than I
ever did from trial and error..

73,
Dave AB7E

p.s. A vertical with however many radials you can afford to lay down
over really lossy ground will be a crummy antenna for low angle work.
That's a fact.

On 3/15/2020 12:37 PM, Edward R Cole wrote:
> OK, well one can study theory for several years before deciding what
> antenna to use ... or just put up something and try it.
> My guess a quarter-wave vertical with some radials will work. How
> well? You will only find out by trying it.
>
> 73, Ed

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Dave New, N8SBE

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by dw-4

Tony Estep

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by David Gilbert

On Sun, Mar 15, 2020 at 5:11 PM David Gilbert <[hidden email]>
wrote:

>
> ...I model EVERYTHING
> before I try to build it and I guarantee it has saved me hours of wasted
> effort and lots of dollars of wasted money. I can also categorically
> state that I have learned FAR more about antennas from modeling than I
> ever did from trial and error.....
>
================
That is so true. As I've posted here before, the 99 bucks you spend for
EZNEC can be the best ham money you ever spent. Its educational value is
really outstanding. No matter what piece of wire you propose to put up, you
can model its radiation pattern and find out so much more than you can from
the rich folklore surrounding antennas. Try it and see!

73,
Tony KT0NY
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NK7Z

Re: Off-Topic: Your advice/suggestion about antenna

https://www.qsl.net/4nec2/

Slightly different, but very usable and free... Also, it supports
variables... Very nice antenna modeling for free...

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 3/16/20 6:39 PM, Tony Estep wrote:

> On Sun, Mar 15, 2020 at 5:11 PM David Gilbert <[hidden email]>
> wrote:
>
>>
>> ...I model EVERYTHING
>> before I try to build it and I guarantee it has saved me hours of wasted
>> effort and lots of dollars of wasted money. I can also categorically
>> state that I have learned FAR more about antennas from modeling than I
>> ever did from trial and error.....
>>
> ================
> That is so true. As I've posted here before, the 99 bucks you spend for
> EZNEC can be the best ham money you ever spent. Its educational value is
> really outstanding. No matter what piece of wire you propose to put up, you
> can model its radiation pattern and find out so much more than you can from
> the rich folklore surrounding antennas. Try it and see!
>
> 73,
> Tony KT0NY
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Jim Brown-10

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Dave New, N8SBE

Blank email.

73, Jim K9YC

On 3/16/2020 2:37 PM, Dave New, N8SBE wrote:

>
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Dave New, N8SBE

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by dw-4

I'm surprised that no one has mentioned MY favorite antenna(s):

1) A 2-el spider-boom quad at 40 ft., covering 20-6M (including the WARC
bands):

https://www.qsl.net/ei7ba/Cubical%20Quad.htm

2) A ZS6BKW dipole, which is 92 ft. long, includes a 40 ft. window line
section, and then 75 ft. of coax. I only use it on 30-80M, using the
ATU on my K3S to tune into it:

https://www.amateurradiosupplies.com/product-p/11003.htm

The quad is a pile-up buster, especially on 20M. It's been up for about
10 years, so needs some TLC, but I'd say that it's held up pretty well,
considering everyone says that quads don't (hold up well).

A 2-el quad performs at or better than a 3-el yagi at low heights above
ground (35 vs 65 ft), and I have the wallpaper to prove it.

The ZS6BKW is up about 35-40 ft. (slopes at one end) and doesn't do so
well for DX, but is a killer for NA contests (NAQP, Sweepstakes, MI QSO
party) from the Midwest.

This all fits on a postage-stamp lot, in a non-HOA neighborhood.

Ya gotta' make do with what you can get up in the air...

73,

-- Dave, N8SBE
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Bob McGraw - K4TAX

Off-Topic: Your advice/suggestion about antenna

As discussed below, what ever you wish to call it, the antenna that is,
being: a G5RV, a double Zepp, an all band antenna, a center fed dipole
and a few more brand names, the center fed dipole with with a balanced
feed and a suitable balun can be matched on all bands, 160M - 6M with
the tuner in the K3S or the KAT500.    There are no magic numbers
regarding lengths.

There are two questions to answer:

(Q) How long should the antenna be?

(A) As long as one has for available space.

(Q) How long should the feed line be?

(A) Long enough to reach from the feed point to the station operating
position.

Now, the length of the wire is relative, being the most one can put up
in the clear. The feedline, be it true open wire of about any impedance
or ~450 window line or 300 ohm transmitting twin lead is all that is
necessary.

Agreed, some combinations of lengths are more difficult to match. If
this occurs, then add some 4 to 6 ft of feed line length, or add 4 to 10
ft to antenna length.   Or shorten the feed line length. The point
being, if one can attain a 2:1 match or better it will radiate quite
efficiently. If your amp won't tolerate this, then a bit more attention
to length is required.

The topic of what balun to use is an extensive discussion. Most baluns
are OK, while some are just purely awful. Some may not alone provide
the necessary common mode current rejection. Power rating of baluns are
for a MATCHED condition, to which we most always use them in a highly
unmatched condition. Thus the suggestion is one consider a much higher
power rated balun than one intends to run. My reference to balun usage
and design is https://www.dj0ip.de/balun-stuff/.

The issue of using a balanced feed system is much easier than the "old
ham lore" will stipulate. Just use common sense. It ain't rocket
science folks, nor does it require a Ph.D to make it work and work
quite well, I might add.

Yes, it is very much OK to bring the balanced feed line all the way to
the operating position where it then attaches to the balun of ones
choice. It is not necessary to have the balun outside and bring the
feed point in via a length of coax. If one is going to use open wire
line or balanced line, then don't screw up the system by introducing a
length of coax to go from the station to the balun in the outside
world.    There will be an unbelievable amount of high SWR on that coax
{and equal amount of loss} and likely a high amount of common mode
current. Do it correct the first time, enjoy the very favorable
results, and forget about the "old ham lore" for it is not correct!
I've only been doing it this way for some 50+ years.

I sit here today with a very modest station. Then antenna is a 256 ft
center fed wire with 450 ohm window line. The center of the antenna is
50 or so feet and the feed line is what ever it took from a 100 ft roll
to get from the feed point, through the attic eve, drop down through the
ceiling to the operating position. There was about 25 ft of 450 ohm
window line left over. I easily work all modes and frequencies 160M -
6M up to 500 watts from my KPA500 and KAT500.   The antenna and feed
line have been in the air and in place for 10+ years and I expect it to
last longer than I do.

Yes, when it rains or snows the SWR goes up, but so what? That is what
the dang tuner is for and it does an excellent job with just the touch
of a button.

If you only have 90 ft for the antenna, that's OK, If you only have 55
ft for the antenna, that's OK. The feed line goes from point A to point
B, whatever that length might be. Shorter lengths of antenna become a
real challenge to get a good match on frequencies lower than the
resonant length but it will work if you can match it.   For get about
the charts, the computer modeling, and put up what you can, in a
reasonable fashion, and begin to enjoy ham radio.

73

Bob, K4TAX

On 3/17/2020 2:42 PM, Dave New, N8SBE wrote:
> 2) A ZS6BKW dipole, which is 92 ft. long, includes a 40 ft. window line
> section, and then 75 ft. of coax. I only use it on 30-80M, using the
> ATU on my K3S to tune into it:
The ZS6BKW is up about 35-40 ft. (slopes at one end) and doesn't do so

well for DX, but is a killer for NA contests (NAQP, Sweepstakes, MI QSO
party) from the Midwest.

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David Gilbert

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Dave New, N8SBE

No, your wallpaper notwithstanding, that statement is not true and it
has been debunked many times.

Dave AB7E

On 3/17/2020 12:42 PM, Dave New, N8SBE wrote:
> A 2-el quad performs at or better than a 3-el yagi at low heights above
> ground (35 vs 65 ft), and I have the wallpaper to prove it.
>
>
>
> -- Dave, N8SBE

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Lyn WØLEN

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Bob McGraw - K4TAX

Bingo! One simple post, Bob, and you've covered pretty much everything anyone needs to know about wire dipole-type antennas. This is exactly the process I worked thru in deciding to build mine last year, with one embellishment - and that was to fine tune the size (I had 400 feet to work with) based on the particular frequency on which I wanted it to actually be a 1.25 wavelength EDZ, for maximum performance on 3.5 MHz (360 feet).

Like you, I am feeding it from the KPA/KAT500 but needed to use a short run of coax into the attic in order to connect to the balun, which is right above the shack ceiling.

At the balanced line feedpoint (I am using approximately 160 feet of 600 ohm open wire “TrueLadderLine”) I measured the impedance with an analyzer across all bands 160 – 6m and calculated that I needed a 4:1 impedance transformer in order to present a workable match to the KAT. But I also wanted a 1:1 Current Mode balun to reduce common mode issues. Coincidentally at just that time, Balun Designs was developing a hybrid balun that actually incorporated both into one package.

I couldn’t be happier with how this all came together. It is broad banded, visually acceptable and most important a great performer.

73

Lyn, W0LEN

"Bob McGraw K4TAX" posted:

As discussed below, what ever you wish to call it, the antenna that is,

being: a G5RV, a double Zepp, an all band antenna, a center fed dipole

and a few more brand names, the center fed dipole with with a balanced

feed and a suitable balun can be matched on all bands, 160M - 6M with

the tuner in the K3S or the KAT500. There are no magic numbers

regarding lengths.

There are two questions to answer:

(Q) How long should the antenna be?

(A) As long as one has for available space.

(Q) How long should the feed line be?

(A) Long enough to reach from the feed point to the station operating

position.

Now, the length of the wire is relative, being the most one can put up

in the clear. The feedline, be it true open wire of about any impedance

or ~450 window line or 300 ohm transmitting twin lead is all that is

necessary.

Agreed, some combinations of lengths are more difficult to match. If

this occurs, then add some 4 to 6 ft of feed line length, or add 4 to 10

ft to antenna length. Or shorten the feed line length. The point

being, if one can attain a 2:1 match or better it will radiate quite

efficiently. If your amp won't tolerate this, then a bit more attention

to length is required.

The topic of what balun to use is an extensive discussion. Most baluns

are OK, while some are just purely awful. Some may not alone provide

the necessary common mode current rejection. Power rating of baluns are

for a MATCHED condition, to which we most always use them in a highly

unmatched condition. Thus the suggestion is one consider a much higher

power rated balun than one intends to run. My reference to balun usage

and design is https://www.dj0ip.de/balun-stuff/.

The issue of using a balanced feed system is much easier than the "old

ham lore" will stipulate. Just use common sense. It ain't rocket

science folks, nor does it require a Ph.D to make it work and work

quite well, I might add.

Yes, it is very much OK to bring the balanced feed line all the way to

the operating position where it then attaches to the balun of ones

choice. It is not necessary to have the balun outside and bring the

feed point in via a length of coax. If one is going to use open wire

line or balanced line, then don't screw up the system by introducing a

length of coax to go from the station to the balun in the outside

world. There will be an unbelievable amount of high SWR on that coax

{and equal amount of loss} and likely a high amount of common mode

current. Do it correct the first time, enjoy the very favorable

results, and forget about the "old ham lore" for it is not correct!

I've only been doing it this way for some 50+ years.

I sit here today with a very modest station. Then antenna is a 256 ft

center fed wire with 450 ohm window line. The center of the antenna is

50 or so feet and the feed line is what ever it took from a 100 ft roll

to get from the feed point, through the attic eve, drop down through the

ceiling to the operating position. There was about 25 ft of 450 ohm

window line left over. I easily work all modes and frequencies 160M -

6M up to 500 watts from my KPA500 and KAT500. The antenna and feed

line have been in the air and in place for 10+ years and I expect it to

last longer than I do.

Yes, when it rains or snows the SWR goes up, but so what? That is what

the dang tuner is for and it does an excellent job with just the touch

of a button.

If you only have 90 ft for the antenna, that's OK, If you only have 55

ft for the antenna, that's OK. The feed line goes from point A to point

B, whatever that length might be. Shorter lengths of antenna become a

real challenge to get a good match on frequencies lower than the

resonant length but it will work if you can match it. For get about

the charts, the computer modeling, and put up what you can, in a

reasonable fashion, and begin to enjoy ham radio.

73

Bob, K4TAX

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Lyn WØLEN

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Bob McGraw - K4TAX

Bingo! One simple post, Bob, and you've covered pretty much everything anyone needs to know about wire dipole-type antennas. This is exactly the process I worked thru in deciding to build mine last year, with one embellishment - and that was to fine tune the size (I had 400 feet to work with) based on the particular frequency on which I wanted it to actually be a 1.25 wavelength EDZ, for maximum performance on 3.5 MHz (360 feet).
Like you, I am feeding it from the KPA/KAT500 but needed to use a short run of coax into the attic in order to connect to the balun, which is right above the shack ceiling.

At the balanced line feedpoint (I am using approximately 160 feet of 600 ohm open wire “TrueLadderLine”) I measured the impedance with an analyzer across all bands 160 – 6m and calculated that I needed a 4:1 impedance transformer in order to present a workable match to the KAT. But I also wanted a 1:1 Current Mode balun to reduce common mode issues. Coincidentally at just that time, Balun Designs was developing a hybrid balun that actually incorporated both into one package.

I couldn’t be happier with how this all came together. It is broad banded, visually acceptable and most important a great performer.

73
Lyn, W0LEN

"Bob McGraw K4TAX" posted:
As discussed below, what ever you wish to call it, the antenna that is,
being: a G5RV, a double Zepp, an all band antenna, a center fed dipole
and a few more brand names, the center fed dipole with with a balanced
feed and a suitable balun can be matched on all bands, 160M - 6M with
the tuner in the K3S or the KAT500. There are no magic numbers
regarding lengths.

There are two questions to answer:

(Q) How long should the antenna be?

(A) As long as one has for available space.

(Q) How long should the feed line be?

(A) Long enough to reach from the feed point to the station operating
position.

Now, the length of the wire is relative, being the most one can put up
in the clear. The feedline, be it true open wire of about any impedance
or ~450 window line or 300 ohm transmitting twin lead is all that is
necessary.

Agreed, some combinations of lengths are more difficult to match. If
this occurs, then add some 4 to 6 ft of feed line length, or add 4 to 10
ft to antenna length. Or shorten the feed line length. The point
being, if one can attain a 2:1 match or better it will radiate quite
efficiently. If your amp won't tolerate this, then a bit more attention
to length is required.

The topic of what balun to use is an extensive discussion. Most baluns
are OK, while some are just purely awful. Some may not alone provide
the necessary common mode current rejection. Power rating of baluns are
for a MATCHED condition, to which we most always use them in a highly
unmatched condition. Thus the suggestion is one consider a much higher
power rated balun than one intends to run. My reference to balun usage
and design is https://www.dj0ip.de/balun-stuff/.

The issue of using a balanced feed system is much easier than the "old
ham lore" will stipulate. Just use common sense. It ain't rocket
science folks, nor does it require a Ph.D to make it work and work
quite well, I might add.

Yes, it is very much OK to bring the balanced feed line all the way to
the operating position where it then attaches to the balun of ones
choice. It is not necessary to have the balun outside and bring the
feed point in via a length of coax. If one is going to use open wire
line or balanced line, then don't screw up the system by introducing a
length of coax to go from the station to the balun in the outside
world. There will be an unbelievable amount of high SWR on that coax
{and equal amount of loss} and likely a high amount of common mode
current. Do it correct the first time, enjoy the very favorable
results, and forget about the "old ham lore" for it is not correct!
I've only been doing it this way for some 50+ years.

I sit here today with a very modest station. Then antenna is a 256 ft
center fed wire with 450 ohm window line. The center of the antenna is
50 or so feet and the feed line is what ever it took from a 100 ft roll
to get from the feed point, through the attic eve, drop down through the
ceiling to the operating position. There was about 25 ft of 450 ohm
window line left over. I easily work all modes and frequencies 160M -
6M up to 500 watts from my KPA500 and KAT500. The antenna and feed
line have been in the air and in place for 10+ years and I expect it to
last longer than I do.

Yes, when it rains or snows the SWR goes up, but so what? That is what
the dang tuner is for and it does an excellent job with just the touch
of a button.

If you only have 90 ft for the antenna, that's OK, If you only have 55
ft for the antenna, that's OK. The feed line goes from point A to point
B, whatever that length might be. Shorter lengths of antenna become a
real challenge to get a good match on frequencies lower than the
resonant length but it will work if you can match it. For get about
the charts, the computer modeling, and put up what you can, in a
reasonable fashion, and begin to enjoy ham radio.

73

Bob, K4TAX

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Jim Brown-10

Re: Off-Topic: Your advice/suggestion about antenna

On 3/17/2020 3:30 PM, Lyn Norstad wrote:
> One simple post, Bob, and you've covered pretty much everything anyone needs to know about wire dipole-type antennas.

NOT! While non-resonant dipoles are certainly viable transmitting
antennas, there is FAR more to know about them, including:

1) Their directional patterns are different on every band;

2) They have very poor rejection of common mode noise on the feedline
unless choked at the FEEDPOINT (i.e. where the feedline connects to the
horizontal wires) and I know of no practical choke to do that effectively.

3) #2 is true because in the common mode circuit, the feedline is part
of the antenna unless the choke disconnects it, and it can only do that
at the feedpoint. The only thing that a choke can do farther down the
line is add high impedance to that common mode circuit, creating a
current minima at that point. Remember, it's an ANTENNA, not a simple
series circuit.

4) A well-balanced transformer coupled tuner CAN present an open to the
common mode circuit, but the rest of the feedline is still part of the
antenna, so any common mode noise received on the feedline is coupled to
the antenna, and from there back down the feedline as a differential
signal.

5) Many years ago, N7WS published his research showing that window line
gets pretty lossy when wet. It's in one of ARRL's excellent Antenna
Compendiums.

Bottom line -- this is one of those antennas that "works," but how well
it "works" depends on your local noise level and whether the station(s)
you want to work are in one of the nulls of its pattern. It's one of
those antennas that was a lot better idea 20 years ago when it was
highly advocated by smart engineers when noise levels were a LOT lower
for most hams than they are today.

73, Jim K9YC
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David Gilbert

Re: Off-Topic: Your advice/suggestion about antenna

Thank you, Jim. I was going to refute some of the comments by K4TAX and
W0LEN myself, but I'm getting tired of challenging every bit of antenna
misinformation that shows up here.

73,
Dave AB7E

On 3/17/2020 4:42 PM, Jim Brown wrote:

> On 3/17/2020 3:30 PM, Lyn Norstad wrote:
>> One simple post, Bob, and you've covered pretty much everything
>> anyone needs to know about wire dipole-type antennas.
>
> NOT! While non-resonant dipoles are certainly viable transmitting
> antennas, there is FAR more to know about them, including:
>
> 1) Their directional patterns are different on every band;
>
> 2) They have very poor rejection of common mode noise on the feedline
> unless choked at the FEEDPOINT (i.e. where the feedline connects to
> the horizontal wires) and I know of no practical choke to do that
> effectively.
>
> 3) #2 is true because in the common mode circuit, the feedline is part
> of the antenna unless the choke disconnects it, and it can only do
> that at the feedpoint. The only thing that a choke can do farther down
> the line is add high impedance to that common mode circuit, creating a
> current minima at that point. Remember, it's an ANTENNA, not a simple
> series circuit.
>
> 4) A well-balanced transformer coupled tuner CAN present an open to
> the common mode circuit, but the rest of the feedline is still part of
> the antenna, so any common mode noise received on the feedline is
> coupled to the antenna, and from there back down the feedline as a
> differential signal.
>
> 5) Many years ago, N7WS published his research showing that window
> line gets pretty lossy when wet. It's in one of ARRL's excellent
> Antenna Compendiums.
>
> Bottom line -- this is one of those antennas that "works," but how
> well it "works" depends on your local noise level and whether the
> station(s) you want to work are in one of the nulls of its pattern.
> It's one of those antennas that was a lot better idea 20 years ago
> when it was highly advocated by smart engineers when noise levels were
> a LOT lower for most hams than they are today.
>
> 73, Jim K9YC
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Vic Rosenthal

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Jim Brown-10

I wonder. Wouldn’t such noise be out of phase on the two halves of the flat top and hence be rejected?

Also, the nulls will be in the same directions (although the tightness of the pattern will vary) when the antenna is operated from half its design frequency to twice that (e.g., from 40 to 10 meters).

...from someone who is using such a system with open wire feed and a Johnson Matchbox.

Victor 4X6GP

> On 18 Mar 2020, at 1:42, Jim Brown <[hidden email]> wrote:
>
> 4) A well-balanced transformer coupled tuner CAN present an open to the common mode circuit, but the rest of the feedline is still part of the antenna, so any common mode noise received on the feedline is coupled to the antenna, and from there back down the feedline as a differential signal.
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Lyn WØLEN

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Jim Brown-10

Jim -

Your comments are well taken ... but mostly invalid for my installation.

For example -

1) Their directional patterns are different on every band;

Exactly, and this plays perfectly into my coverage needs. For example, I
need (and designed for) 80 meter coverage concentrated in a N-S direction.
For every other band, I need (and designed for) more of an omni pattern.
That works best for me and is reasonably well provided by this antenna's
multi-lobe patterns.

2) They have very poor rejection of common mode noise on the feedline
unless choked at the FEEDPOINT (i.e. where the feedline connects to the
horizontal wires) and I know of no practical choke to do that effectively.

I have a hybrid 4:1 / 1:1 balun at the shack end of the balanced feedline
and have absolutely no issues. None. It is a Balun Designs 4116t.

5) Many years ago, N7WS published his research showing that window
line gets pretty lossy when wet. It's in one of ARRL's excellent Antenna
Compendiums.

Agreed, and that's why I didn't use window line. I used open-wire, or true
ladder line, from TrueLadderLine.com. Rain has no effect unless the line
itself is pressed against tree leaves (I do have to do a little tree
trimming now and then).

Noise level is markedly lower than reported by other hams in the area,
whether using vertical or compromised horizontal antennas. My noise level
went down at least 2-3 S units in switching from the attic-mounted G5RV Jr,
while both received and transmitted signals are higher by a similar amount.

Bottom line is that it does what it is intended to do, and does it quite
well.

73

Lyn, W0LEN

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Bob McGraw - K4TAX

Re: Off-Topic: Your advice/suggestion about antenna

I have to agree with Lyn on several points.   I do agree the directional
pattern is different on every band. For me, that suffices as I am not
one to aggressively chase DX.   If you need specific directional
patterns, then other considerations for antennas should be undertaken.

On point #2, the balanced feed line is twisted at my installation. This
is one advantage to the vinyl covered line. This makes essentially a
twisted pair which Bell Labs many years show is a way to minimize
induction into the feed line.    In transforming from balanced to
unbalanced, I use two "baluns" at the shack end of the feed line. One
is a 4:1 dual core balun operating as a wide band transformer and the
second is a 1:1 balun operating as a balanced to unbalanced
configuration. It also provides a significant amount of common mode
current rejection. This has been verified by measurement of the common
mode current on the shield of the short jumper between the balun and the
ATU. {See https://www.dj0ip.de/balun-stuff/ }

As to the research N7WS,   I've read his paper several times. In fact,
a fresh copy is on my desk.   Due to test equipment limitations, he did
his wet/dry line measurements at 50 MHz and higher with a short piece of
feed line.    I did my measurements between 1.8 MHz and 30 MHz with 100
ft of feed line. The line was measured, for wet/dry purposes, in a
matched impedance configuration between 1.8 MHz and 30 MHz.    I agree
with his data on velocity factor changes but can not agree on increased
loss data.

The work of KV5R where he references; "Many amateurs use non-resonant
(even random length) antennas fed with open wire lines and tuners. They
radiate signals just as well as those fed with coaxial cable and
resonant antennas. ...... ARRL Antenna Book, Ch2" As long as the
antenna length is 1/2 wavelength at the lowest frequency the efficiency
is near 90%.     {See KV5R.Com}

The work of G3TXQ seems to contradict parts of the work done by N7WS.
His measurement for wet/dry line being 60ft of 300 ohm line
configuration with a 6:1 SWR does more agree with my measurements using
100 ft of line. Thus 60 ft of dry line at 27.0 MHz shows 0.71 dB loss
and 0.93 dB loss when wet.    His measurements of 450 ohm window line
fall within the same range of loss measurements between wet or dry.

As to noise in the local area at my QTH, having two different antennas,
one being a resonant dipole fed with a 1:1 current balun at the feed
point and RG-213 and the other being a 256 ft center fed wire with a
balanced feed I do not find the balanced fed antenna to be any more
prone to noise than the resonant dipole on 80M and 20M.    There is a
bit of a skew in orientation due to placement of the ends.

A 2nd test, at a 2nd site which easily allows one antenna to be pulled
in place and measured and then lowered and the a 2nd antenna pulled into
the same location, I find again there is no difference between a coax
fed antenna and one fed with balanced feed line, in terms of noise
pickup.   Field strength measurements at several points at a distance of
approximately 1 mile is indeterminable between the two.

As the song says "that's my story and I'm sticking to it".

73

Bob,K4TAX

On 3/18/2020 7:39 AM, Lyn Norstad wrote:

> Jim -
>
>
>
> Your comments are well taken ... but mostly invalid for my installation.
>
>
>
> For example -
>
>
>
> 1) Their directional patterns are different on every band;
>
>
>
> Exactly, and this plays perfectly into my coverage needs. For example, I
> need (and designed for) 80 meter coverage concentrated in a N-S direction.
> For every other band, I need (and designed for) more of an omni pattern.
> That works best for me and is reasonably well provided by this antenna's
> multi-lobe patterns.
>
>
>
> 2) They have very poor rejection of common mode noise on the feedline
> unless choked at the FEEDPOINT (i.e. where the feedline connects to the
> horizontal wires) and I know of no practical choke to do that effectively.
>
>
>
> I have a hybrid 4:1 / 1:1 balun at the shack end of the balanced feedline
> and have absolutely no issues. None. It is a Balun Designs 4116t.
>
>
>
> 5) Many years ago, N7WS published his research showing that window
> line gets pretty lossy when wet. It's in one of ARRL's excellent Antenna
> Compendiums.
>
>
>
> Agreed, and that's why I didn't use window line. I used open-wire, or true
> ladder line, from TrueLadderLine.com. Rain has no effect unless the line
> itself is pressed against tree leaves (I do have to do a little tree
> trimming now and then).
>
>
>
> Noise level is markedly lower than reported by other hams in the area,
> whether using vertical or compromised horizontal antennas. My noise level
> went down at least 2-3 S units in switching from the attic-mounted G5RV Jr,
> while both received and transmitted signals are higher by a similar amount.
>
>
>
>
> Bottom line is that it does what it is intended to do, and does it quite
> well.
>
>
>
> 73
>
> Lyn, W0LEN
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Jim Brown-10

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Lyn WØLEN

On 3/18/2020 5:39 AM, Lyn Norstad wrote:
> I have a hybrid 4:1 / 1:1 balun at the shack end of the balanced
> feedline and have absolutely no issues.

Hi Len,

The problem is noise pickup on the line. I think I remember that your
QTH is relatively isolated, hence not much local noise. The other
question is, how would you know if you had an issue without an A/B
comparison to a resonant dipole with a choke at the feedpoint?

None. It is a Balun Designs 4116t.

This company appears to have no clue about how chokes work to kill
noise, but they're very good at selling them. Their definition of
"working" seems to be that the customer pays and the "balun" doesn't
burn up. Last year, a member of our contest club building a station in
the Caribbean asked me to measure one of their products. It looked
NOTHING like the data sheet on their website. After I circulated the
data to a few engineers as a "heads up," the plot disappeared from their
website.

73, Jim K9YC

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Jim Brown-10

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Bob McGraw - K4TAX

Hi Bob,

On 3/18/2020 7:18 AM, Bob McGraw K4TAX wrote:

> On point #2, the balanced feed line is twisted at my installation. This
> is one advantage to the vinyl covered line. This makes essentially a
> twisted pair which Bell Labs many years show is a way to minimize
> induction into the feed line. In transforming from balanced to
> unbalanced, I use two "baluns" at the shack end of the feed line. One
> is a 4:1 dual core balun operating as a wide band transformer and the
> second is a 1:1 balun operating as a balanced to unbalanced
> configuration. It also provides a significant amount of common mode
> current rejection. This has been verified by measurement of the common
> mode current on the shield of the short jumper between the balun and the
> ATU. {See https://www.dj0ip.de/balun-stuff/ }

Several points. First, twisting applies ONLY to coupling INTO the line
-- that is, the DIFFERENTIAL circuit.

Second, to be effective for that, distance between twists must be a very
small fraction of the wavelength. For example, the high twist rate
(called the "lay" by cable engineers) of CAT5 prevents very good
rejection of differential mode crosstalk into the low HF spectrum.

Measuring common mode current at the shack end of a line tells us
NOTHING about common mode current anywhere else on the line, because,
like any antenna, current varies along the wires that form it. In the
common mode circuit, the feedline is a single wire connected to the
center of the antenna on one end.

With no choke and no transformer in the shack, the connection is to
"ground," whatever that is. That causes the current to be near a maxima,
depending on what "ground" is, and current on the wire varies along the
wire (the line) like with any other antenna. A quarter wave up from the
maxima it will be a current minima and a voltage maxima; a half wave up
is another current maxima. This is not a transmission line effect, it is
an antenna effect; VF ~ 0.98, the VF of a wire with insulation.

An effective choke and/or a transformer at the shack end forces a
current MINIMA at that point, with maxima and minima along the line up
to the intentional antenna. A "balun" that is inductive or capacitive at
the frequency of interest will modify that current distribution; so will
a transformer that has capacitance between windings.

On 3/18/2020 7:18 AM, Bob McGraw K4TAX wrote:
> As to the research N7WS, I've read his paper several times. In fact,
> a fresh copy is on my desk. Due to test equipment limitations, he did
> his wet/dry line measurements at 50 MHz and higher with a short piece of
> feed line. I did my measurements between 1.8 MHz and 30 MHz with 100
> ft of feed line. The line was measured, for wet/dry purposes, in a
> matched impedance configuration between 1.8 MHz and 30 MHz. I agree
> with his data on velocity factor changes but can not agree on increased
> loss data.

Wes's choice of VHF is quite reasonable, and on a percentage basis, IS
representative of loss at MF and HF. Because loss for lines using
non-ferrous conductors increases approximately as the square root of
frequency, it's easier to measure at VHF, but the curves for all such
cables will be approximately parallel to each other. This can be seen in
the plot on page 2 of this link. All of the lines are approximately
parallel except for the kW twinlead (CCS conductors) and the coax with a
CCS center.

http://k9yc.com/Coax-Stubs.pdf

As to your tests between antennas at your QTH -- what matters is signal
to noise on RX, and the differences are likely to be in the 3-9 dB
range, depending on what noise sources are around you. To observe them,
we must do A/B comparisons on many WEAK signals, switching between the
antennas many times on each signal. Where this matters is copying weak
signals -- we won't hear differences on stronger ones. And it only
matters if your QTH is noisy.

73, Jim K9YC

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Jim Brown-10

Re: Off-Topic: Your advice/suggestion about antenna

In reply to this post by Jim Brown-10

My work has been published for ten years, the most current work for two
years, and there have been millions of downloads.

73, Jim

On 3/18/2020 12:29 PM, Lyn Norstad wrote:
> so I am sure they would welcome your expertise.
>
> Perhaps you should make your services available to them.
>

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