Re: Topband: FW: Hi-Z Around Trees

[Gary Smith]

My 8 element HI-Z array array is 
definitely in woods with a couple trees 
unfortunately located within 4 or so feet 
of the elements.

How this performs with 160 DX, I'll know 
better after a few contests and the band 
opens up a bit. One thing for sure, I'm 
finding this system very sensitive and 
directive. Much less noise than I am used 
to on 160 with my other Rx antenna with 
older preamps and it was no slouch.

Try it, you'll like it.

73,

Gary
KA1J

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Re: Topband: FW: Hi-Z Around Trees

[Mike Smith VE9AA]

I don't have a HI-Z, but I do have many antennas in the trees here. (and
have in the past at other locations too)

Recently, I have installed all wire & rope 4-squares on 40 & 80 and a 2-el
on 160m, all in and in some cases attached to or gently touching,

(gasp!)(wait for it.) dunh dunh dunh..TREES !)

 

Worse yet, the 80m/160m arrays are partially nested and the 40m one is
partially nested in the corner of the 80m one.(maybe that's a separate
thread)

 

I posted my results here in 2 separate posts some weeks back, so I won't
repeat the data, except to say the only non-scientific anomaly's I see are
when the 80m array is aimed to the NW through some metal clutter and 2 sheds
(full of wiring and metal).

 

I used trees and did some nesting of arrays nothing bad happened like the
naysayers warned.

 

Would I get 1dB more gain and 2dB more F/B if they were aluminum verticals
out in the middle of a 40acre field?  Probably.

 

I used what I had.

 

I'd worry more about a nearby house, a utility pole full of wires, your
neighbours 18-wheeler, anything large and metallic than I would the harmless
but helpful tree.

 

Mike VE9AA

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

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Re: Topband: FW: Hi-Z Around Trees

[John Harden, D.M.D.]

I have a Hi-Z 4-8 PRO down the hill in a flood plain by the creek. I had 
the area bush-hogged out but there are trees everywhere. It works great 
and is in the smaller circle configuration with an 85 ft diameter spacing..


It compares with my Waller Flag up the hill on a 45G 100 ft Tower at 95 
feet though the FLAG is a better long haul antenna with its horizontal 
polarization.
The flag has a 40 foot boom and is fed with with 100 ohm Twinax to the 
transformer at the tower base. From there I run LMR-600 to the shack 
where I have the stellar N4IS pre-amplifier with 40 dB of amplification. 
The FLAG is turned with a TIC Ring Rotor.


It's good to have both...

K1ZM states in his 160 book that it's best to have as many RX antennas 
as possible.


73,

John, W4NU
Atlanta, GA


On 11/14/2016 5:21 PM, Jeff AC0C wrote:
Sorry to hear that.  But to avoid confusion for the guy asking about 
the trees case, we should be crystal clear that houses (which are 
filled with metal stuff) and antennas (made of usually resonant + 
metal stuff) are in a *completely different category* than a minimally 
interacting thing like a tree, especially when it's several feet from 
the antenna.


73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message- From: Joe Galicic
Sent: Monday, November 14, 2016 3:54 PM
To: p...@paulferguson.us ; topband@contesting.com
Cc: k7...@msn.com
Subject: Re: Topband: FW: Hi-Z Around Trees

I could never get my hiz 2-3 (3 element,4 directions) working on my 
small quarter acre lot.  Too close to trees, houses and antennas.  
Worked with

Lee for a long time trying.  No luck.  N3HEE


Sent from XFINITY Connect Mobile App

-Original Message-

From: p...@paulferguson.us
To: topband@contesting.com
Cc: k7...@msn.com
Sent: 2016-11-14 9:49:58 AM
Subject: Re: Topband: FW: Hi-Z Around Trees

Lee,

Thanks for the guidance.

I plan to use 20-foot fiberglass tube with a wire down the center for
Hi-Z array elements. Would you expect sensitivity to nearby trees to be
about the same for these wire elements versus aluminum tube elements.

73,
Paul
K5ESW





  Greetings Top-Banders, I have been away for a couple days, sorry for
  the late comments.
The fact is, for me there is no definitive answer to the effect of
trees on the Hi-Z arrays. I have made tests measuring phase shifts
and amplitude changes with a variety of objects around these
elements. My original thoughts after the tests were that any tree or


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Re: Topband: FW: Hi-Z Around Trees

[Jeff AC0C]

Sorry to hear that.  But to avoid confusion for the guy asking about the 
trees case, we should be crystal clear that houses (which are filled with 
metal stuff) and antennas (made of usually resonant + metal stuff) are in a 
*completely different category* than a minimally interacting thing like a 
tree, especially when it's several feet from the antenna.


73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message- 
From: Joe Galicic

Sent: Monday, November 14, 2016 3:54 PM
To: p...@paulferguson.us ; topband@contesting.com
Cc: k7...@msn.com
Subject: Re: Topband: FW: Hi-Z Around Trees

I could never get my hiz 2-3 (3 element,4 directions) working on my small 
quarter acre lot.  Too close to trees, houses and antennas.  Worked with

Lee for a long time trying.  No luck.  N3HEE


Sent from XFINITY Connect Mobile App

-Original Message-

From: p...@paulferguson.us
To: topband@contesting.com
Cc: k7...@msn.com
Sent: 2016-11-14 9:49:58 AM
Subject: Re: Topband: FW: Hi-Z Around Trees

Lee,

Thanks for the guidance.

I plan to use 20-foot fiberglass tube with a wire down the center for
Hi-Z array elements. Would you expect sensitivity to nearby trees to be
about the same for these wire elements versus aluminum tube elements.

73,
Paul
K5ESW





  Greetings Top-Banders, I have been away for a couple days, sorry for
  the late comments.
The fact is, for me there is no definitive answer to the effect of
trees on the Hi-Z arrays. I have made tests measuring phase shifts
and amplitude changes with a variety of objects around these
elements. My original thoughts after the tests were that any tree or


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_
Topband Reflector Archives - http://www.contesting.com/_topband 


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Re: Topband: FW: Hi-Z Around Trees

[Joe Galicic]

I could never get my hiz 2-3 (3 element,4 directions) working on my small 
quarter acre lot.  Too close to trees, houses and antennas.  Worked with 
Lee for a long time trying.  No luck.  N3HEE 


Sent from XFINITY Connect Mobile App

-Original Message-

From: p...@paulferguson.us
To: topband@contesting.com
Cc: k7...@msn.com
Sent: 2016-11-14 9:49:58 AM 
Subject: Re: Topband: FW: Hi-Z Around Trees

Lee,

Thanks for the guidance. 

I plan to use 20-foot fiberglass tube with a wire down the center for  
Hi-Z array elements. Would you expect sensitivity to nearby trees to be 
about the same for these wire elements versus aluminum tube elements.

73,
Paul
K5ESW


> 
> 
>   Greetings Top-Banders, I have been away for a couple days, sorry for
>   the late comments.
> The fact is, for me there is no definitive answer to the effect of
> trees on the Hi-Z arrays. I have made tests measuring phase shifts
> and amplitude changes with a variety of objects around these
> elements. My original thoughts after the tests were that any tree or

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Re: Topband: FW: Hi-Z Around Trees

[daraymond]

I have done similar tests with my Hi-Z 8 circle 160m array and agree with 
Lee's assessment.  My test were based on over the air received signal levels 
on individual elements.  (There are more uncontrollable variations in this 
method as opposed to using C measurements, which is better).  My array uses 
26' elements with one element being very close to various tree branches 
(mainly oak and elm) that had grown close over the past few years.  The 
branches were close enough that, under certain wind conditions, they 
actually lightly brushed against the element (which did have very noticeable 
affect on signal levels).  Most of the time they were within about two feet 
along side the top of the element.  I had a tree crew come in (I couldn't 
get to them safely myself as the trees were in an adjacent ravine) and 
remove the branches and noticed only a small change (maybe a db or so) in 
received signal level.  I'm guessing the type of tree or foliage, the 
moisture content in the foliage at the time, etc., all have some bearing on 
how much the branches affect signal levels.  In any case, I think if your 
foliage is more than 3' or 4' from the element you should be in good shape.


73. . . Dave, W0FLS

-Original Message- 
From: Lee STRAHAN

Sent: Sunday, November 13, 2016 11:54 PM
To: topband@contesting.com
Subject: Topband: FW: Hi-Z Around Trees



 Greetings Top-Banders, I have been away for a couple days, sorry for the 
late comments.
   The fact is, for me there is no definitive answer to the effect of trees 
on the Hi-Z arrays. I have made tests measuring phase shifts and amplitude 
changes with a variety of objects around these elements. My original 
thoughts after the tests were that any tree or large foliage would have to a 
minimum of 5 feet distance from the elements. There are not many trees where 
I live so this sort of test is very difficult. One of the things I did was 
to measure the capacitance of the elements as a source impedance to the 
amps. Changes in this capacitance would make amplitude changes at the 
amplifiers. The only real changes I measured after numerous tests were when 
I would approach the element with the capacitance meter in operation. When a 
6 foot person approached the elements I could see changes in the element at 
about 3 feet separation. Nothing at 5 feet. This was with a 24 foot aluminum 
element and a low capacity mounting insulator. This capacitance test was 
more sensitive than my voltage and phase measurements.
  Mike NI7T installed a 4 square system in the forest behind his cabin. 
Many pine and redwood trees were within 5 feet of the elements. We were 
never able to discern any negative affects to his array. Front to back 
rejection was well within nominal and front patterns seemed proper. The 
array remained sensitive to weak signals. Larry K1UO had his array in a 
brush patch. As I recall I suggested a 5 foot spacing which he did. If you 
have not seen the DX Larry posts from Maine you are missing something. In 
other words it was apparently adequate spacing.
  So with the 24 foot elements ¾ inch diameter that have around a 75pf 
source capacitance I would say you are pretty safe at 5 feet. Shorter 
elements with significantly less source capacitance would surely need more 
spacing. A 12 foot similar element drops clear down to 42pf source 
capacitance. I would hazard a guess that arrays using short whip elements at 
around 25pf would be quite sensitive to close trees or foliage.
   Barring all this I am confident you would be absolutely safe in my 
estimation at 10 feet distance of brush, tall foliage, and trees from the 
elements.


Lee  K7TJR


Hello Jim


My HI-Z 4 square has trees about 15 feet away from two of the elements (I 
can make exact distance measurements if that would help you).


I do not "think" the trees interact in my setup - but I am not 100% sure. 
Even my HI-Z 8 circle has trees pretty close to 3 elements (10 feet). 
Without measuring changes (impedance) to these elements due to location, I 
am not sure how else to know. However, given Frank's comments - I will be 
trimming some trees today!


I am certain K7TJR is the expert on this has he has heard from users about 
element location and performance for years.


I wish you the best.

73
Tim K3LR


From: donov...@starpower.net<mailto:donov...@starpower.net> 
[mailto:donov...@starpower.net]

Sent: Saturday, November 12, 2016 6:57 PM
To: j...@audiosystemsgroup.com<mailto:j...@audiosystemsgroup.com>
Cc: Lee K7TJR; k...@k3lr.com<mailto:k...@k3lr.com>; Joel Harrison
Subject: Re: Hi-Z Around Trees

Hi Jim,

My comments about short verticals not performing well near trees
applies only to high impedance verticals.   Low impedance are
little affected.

73
Frank
W3LPL


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-
No virus found in this message.
Checked 

Re: Topband: FW: Hi-Z Around Trees

[Tree]

I have a Hi-Z 4 element array that is wedged into the only available space
I could figure out.  It breaks lots of rules:

1. Two of the elements are less than 60 feet away from the transmitting
vertical (a loaded tower).  One of them is about 40 feet away.
2. One of the elements is essentially in a tree and I noticed that some of
the small branches were actually touching the top of the element (was going
to trim them but haven't gotten to it yet).
3. Two of the elements are about 8 feet from an metal barb wire fence +
electric fence .

However, the array works just as I would expect it to.  Last Winter - I had
a 1200 foot Beverage going to the East and while I would say the Beverage
out performed the Hi-Z array - I would say it wasn't more than a db or two.

Certainly one should always do the best they can to isolate it as much as
possible - but don't let a less than optimal situation stop you from trying.

73 Tree N6TR

On Mon, Nov 14, 2016 at 5:07 AM, Michael Walker 
wrote:

> Same reply.  At our contest station, we have a 300M beverage just running
> through the woods and tree branches in Northern Ontario
>
> No scientific testing, but it just worked.
>
> Mike va3mw
>
>
> On Mon, Nov 14, 2016 at 7:49 AM, Paul Mclaren  wrote:
>
> > On a similar note can I ask about beverages touching leaves and other
> > vegetagian.   Will this result in poor performance and if so is it
> > significant?
> >
> > Regards
> >
> > Paul MM0ZBH
> >
> > On 14 November 2016 at 12:41, Michael Walker 
> wrote:
> >
> >> For my 80CW and 160 verticals, I have wires suspended through 90 ft tall
> >> evergreens.  I have been doing that for years and I put them in place
> >> using
> >> a drone (long before everyone was doing it).
> >>
> >> I have radials underneath.  In fact, they are on a common feedpoint.
> >>
> >> Based on my 160M or 80M WSPR / JT65 testing, I would be hard pressed to
> >> say
> >> that much if any RF is being absorbed by the trees.
> >>
> >> In my case, I work with what I have available.  For me, they just work.
> >>
> >> Mike va3mw
> >>
> >>
> >> On Mon, Nov 14, 2016 at 12:54 AM, Lee STRAHAN  wrote:
> >>
> >> >
> >> >
> >> >   Greetings Top-Banders, I have been away for a couple days, sorry for
> >> the
> >> > late comments.
> >> > The fact is, for me there is no definitive answer to the effect of
> >> > trees on the Hi-Z arrays. I have made tests measuring phase shifts and
> >> > amplitude changes with a variety of objects around these elements. My
> >> > original thoughts after the tests were that any tree or large foliage
> >> would
> >> > have to a minimum of 5 feet distance from the elements. There are not
> >> many
> >> > trees where I live so this sort of test is very difficult. One of the
> >> > things I did was to measure the capacitance of the elements as a
> source
> >> > impedance to the amps. Changes in this capacitance would make
> amplitude
> >> > changes at the amplifiers. The only real changes I measured after
> >> numerous
> >> > tests were when I would approach the element with the capacitance
> meter
> >> in
> >> > operation. When a 6 foot person approached the elements I could see
> >> changes
> >> > in the element at about 3 feet separation. Nothing at 5 feet. This was
> >> with
> >> > a 24 foot aluminum element and a low capacity mounting insulator. This
> >> > capacitance test was more sensitive than my voltage and phase
> >> measurements.
> >> >Mike NI7T installed a 4 square system in the forest behind his
> cabin.
> >> > Many pine and redwood trees were within 5 feet of the elements. We
> were
> >> > never able to discern any negative affects to his array. Front to back
> >> > rejection was well within nominal and front patterns seemed proper.
> The
> >> > array remained sensitive to weak signals. Larry K1UO had his array in
> a
> >> > brush patch. As I recall I suggested a 5 foot spacing which he did. If
> >> you
> >> > have not seen the DX Larry posts from Maine you are missing something.
> >> In
> >> > other words it was apparently adequate spacing.
> >> >So with the 24 foot elements ¾ inch diameter that have around a
> 75pf
> >> > source capacitance I would say you are pretty safe at 5 feet. Shorter
> >> > elements with significantly less source capacitance would surely need
> >> more
> >> > spacing. A 12 foot similar element drops clear down to 42pf source
> >> > capacitance. I would hazard a guess that arrays using short whip
> >> elements
> >> > at around 25pf would be quite sensitive to close trees or foliage.
> >> > Barring all this I am confident you would be absolutely safe in my
> >> > estimation at 10 feet distance of brush, tall foliage, and trees from
> >> the
> >> > elements.
> >> >
> >> > Lee  K7TJR
> >> >
> >> > >>Hello Jim
> >> >
> >> > My HI-Z 4 square has trees about 15 feet away from two of the elements
> >> (I
> >> > can make exact distance measurements if that would help 

Re: Topband: FW: Hi-Z Around Trees

[Paul Ferguson]

Lee,

Thanks for the guidance. 

I plan to use 20-foot fiberglass tube with a wire down the center for  
Hi-Z array elements. Would you expect sensitivity to nearby trees to be 
about the same for these wire elements versus aluminum tube elements.

73,
Paul
K5ESW


> 
> 
>   Greetings Top-Banders, I have been away for a couple days, sorry for
>   the late comments.
> The fact is, for me there is no definitive answer to the effect of
> trees on the Hi-Z arrays. I have made tests measuring phase shifts
> and amplitude changes with a variety of objects around these
> elements. My original thoughts after the tests were that any tree or

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: FW: Hi-Z Around Trees

[Michael Walker]

Same reply.  At our contest station, we have a 300M beverage just running
through the woods and tree branches in Northern Ontario

No scientific testing, but it just worked.

Mike va3mw


On Mon, Nov 14, 2016 at 7:49 AM, Paul Mclaren  wrote:

> On a similar note can I ask about beverages touching leaves and other
> vegetagian.   Will this result in poor performance and if so is it
> significant?
>
> Regards
>
> Paul MM0ZBH
>
> On 14 November 2016 at 12:41, Michael Walker  wrote:
>
>> For my 80CW and 160 verticals, I have wires suspended through 90 ft tall
>> evergreens.  I have been doing that for years and I put them in place
>> using
>> a drone (long before everyone was doing it).
>>
>> I have radials underneath.  In fact, they are on a common feedpoint.
>>
>> Based on my 160M or 80M WSPR / JT65 testing, I would be hard pressed to
>> say
>> that much if any RF is being absorbed by the trees.
>>
>> In my case, I work with what I have available.  For me, they just work.
>>
>> Mike va3mw
>>
>>
>> On Mon, Nov 14, 2016 at 12:54 AM, Lee STRAHAN  wrote:
>>
>> >
>> >
>> >   Greetings Top-Banders, I have been away for a couple days, sorry for
>> the
>> > late comments.
>> > The fact is, for me there is no definitive answer to the effect of
>> > trees on the Hi-Z arrays. I have made tests measuring phase shifts and
>> > amplitude changes with a variety of objects around these elements. My
>> > original thoughts after the tests were that any tree or large foliage
>> would
>> > have to a minimum of 5 feet distance from the elements. There are not
>> many
>> > trees where I live so this sort of test is very difficult. One of the
>> > things I did was to measure the capacitance of the elements as a source
>> > impedance to the amps. Changes in this capacitance would make amplitude
>> > changes at the amplifiers. The only real changes I measured after
>> numerous
>> > tests were when I would approach the element with the capacitance meter
>> in
>> > operation. When a 6 foot person approached the elements I could see
>> changes
>> > in the element at about 3 feet separation. Nothing at 5 feet. This was
>> with
>> > a 24 foot aluminum element and a low capacity mounting insulator. This
>> > capacitance test was more sensitive than my voltage and phase
>> measurements.
>> >Mike NI7T installed a 4 square system in the forest behind his cabin.
>> > Many pine and redwood trees were within 5 feet of the elements. We were
>> > never able to discern any negative affects to his array. Front to back
>> > rejection was well within nominal and front patterns seemed proper. The
>> > array remained sensitive to weak signals. Larry K1UO had his array in a
>> > brush patch. As I recall I suggested a 5 foot spacing which he did. If
>> you
>> > have not seen the DX Larry posts from Maine you are missing something.
>> In
>> > other words it was apparently adequate spacing.
>> >So with the 24 foot elements ¾ inch diameter that have around a 75pf
>> > source capacitance I would say you are pretty safe at 5 feet. Shorter
>> > elements with significantly less source capacitance would surely need
>> more
>> > spacing. A 12 foot similar element drops clear down to 42pf source
>> > capacitance. I would hazard a guess that arrays using short whip
>> elements
>> > at around 25pf would be quite sensitive to close trees or foliage.
>> > Barring all this I am confident you would be absolutely safe in my
>> > estimation at 10 feet distance of brush, tall foliage, and trees from
>> the
>> > elements.
>> >
>> > Lee  K7TJR
>> >
>> > >>Hello Jim
>> >
>> > My HI-Z 4 square has trees about 15 feet away from two of the elements
>> (I
>> > can make exact distance measurements if that would help you).
>> >
>> > I do not "think" the trees interact in my setup - but I am not 100%
>> sure.
>> > Even my HI-Z 8 circle has trees pretty close to 3 elements (10 feet).
>> > Without measuring changes (impedance) to these elements due to
>> location, I
>> > am not sure how else to know. However, given Frank's comments - I will
>> be
>> > trimming some trees today!
>> >
>> > I am certain K7TJR is the expert on this has he has heard from users
>> about
>> > element location and performance for years.
>> >
>> > I wish you the best.
>> >
>> > 73
>> > Tim K3LR
>> >
>> > 
>> > From: donov...@starpower.net [mailto:
>> > donov...@starpower.net]
>> > Sent: Saturday, November 12, 2016 6:57 PM
>> > To: j...@audiosystemsgroup.com
>> > Cc: Lee K7TJR; k...@k3lr.com; Joel Harrison
>> > Subject: Re: Hi-Z Around Trees
>> >
>> > Hi Jim,
>> >
>> > My comments about short verticals not performing well near trees
>> > applies only to high impedance verticals.   Low impedance are
>> > little affected.
>> >
>> > 73
>> > Frank
>> > W3LPL
>> > 
>> >
>> > _

Re: Topband: FW: Hi-Z Around Trees

[Paul Mclaren]

On a similar note can I ask about beverages touching leaves and other
vegetagian.   Will this result in poor performance and if so is it
significant?

Regards

Paul MM0ZBH

On 14 November 2016 at 12:41, Michael Walker  wrote:

> For my 80CW and 160 verticals, I have wires suspended through 90 ft tall
> evergreens.  I have been doing that for years and I put them in place using
> a drone (long before everyone was doing it).
>
> I have radials underneath.  In fact, they are on a common feedpoint.
>
> Based on my 160M or 80M WSPR / JT65 testing, I would be hard pressed to say
> that much if any RF is being absorbed by the trees.
>
> In my case, I work with what I have available.  For me, they just work.
>
> Mike va3mw
>
>
> On Mon, Nov 14, 2016 at 12:54 AM, Lee STRAHAN  wrote:
>
> >
> >
> >   Greetings Top-Banders, I have been away for a couple days, sorry for
> the
> > late comments.
> > The fact is, for me there is no definitive answer to the effect of
> > trees on the Hi-Z arrays. I have made tests measuring phase shifts and
> > amplitude changes with a variety of objects around these elements. My
> > original thoughts after the tests were that any tree or large foliage
> would
> > have to a minimum of 5 feet distance from the elements. There are not
> many
> > trees where I live so this sort of test is very difficult. One of the
> > things I did was to measure the capacitance of the elements as a source
> > impedance to the amps. Changes in this capacitance would make amplitude
> > changes at the amplifiers. The only real changes I measured after
> numerous
> > tests were when I would approach the element with the capacitance meter
> in
> > operation. When a 6 foot person approached the elements I could see
> changes
> > in the element at about 3 feet separation. Nothing at 5 feet. This was
> with
> > a 24 foot aluminum element and a low capacity mounting insulator. This
> > capacitance test was more sensitive than my voltage and phase
> measurements.
> >Mike NI7T installed a 4 square system in the forest behind his cabin.
> > Many pine and redwood trees were within 5 feet of the elements. We were
> > never able to discern any negative affects to his array. Front to back
> > rejection was well within nominal and front patterns seemed proper. The
> > array remained sensitive to weak signals. Larry K1UO had his array in a
> > brush patch. As I recall I suggested a 5 foot spacing which he did. If
> you
> > have not seen the DX Larry posts from Maine you are missing something. In
> > other words it was apparently adequate spacing.
> >So with the 24 foot elements ¾ inch diameter that have around a 75pf
> > source capacitance I would say you are pretty safe at 5 feet. Shorter
> > elements with significantly less source capacitance would surely need
> more
> > spacing. A 12 foot similar element drops clear down to 42pf source
> > capacitance. I would hazard a guess that arrays using short whip elements
> > at around 25pf would be quite sensitive to close trees or foliage.
> > Barring all this I am confident you would be absolutely safe in my
> > estimation at 10 feet distance of brush, tall foliage, and trees from the
> > elements.
> >
> > Lee  K7TJR
> >
> > >>Hello Jim
> >
> > My HI-Z 4 square has trees about 15 feet away from two of the elements (I
> > can make exact distance measurements if that would help you).
> >
> > I do not "think" the trees interact in my setup - but I am not 100% sure.
> > Even my HI-Z 8 circle has trees pretty close to 3 elements (10 feet).
> > Without measuring changes (impedance) to these elements due to location,
> I
> > am not sure how else to know. However, given Frank's comments - I will be
> > trimming some trees today!
> >
> > I am certain K7TJR is the expert on this has he has heard from users
> about
> > element location and performance for years.
> >
> > I wish you the best.
> >
> > 73
> > Tim K3LR
> >
> > 
> > From: donov...@starpower.net [mailto:
> > donov...@starpower.net]
> > Sent: Saturday, November 12, 2016 6:57 PM
> > To: j...@audiosystemsgroup.com
> > Cc: Lee K7TJR; k...@k3lr.com; Joel Harrison
> > Subject: Re: Hi-Z Around Trees
> >
> > Hi Jim,
> >
> > My comments about short verticals not performing well near trees
> > applies only to high impedance verticals.   Low impedance are
> > little affected.
> >
> > 73
> > Frank
> > W3LPL
> > 
> >
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> >
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Re: Topband: FW: Hi-Z Around Trees

[Michael Walker]

For my 80CW and 160 verticals, I have wires suspended through 90 ft tall
evergreens.  I have been doing that for years and I put them in place using
a drone (long before everyone was doing it).

I have radials underneath.  In fact, they are on a common feedpoint.

Based on my 160M or 80M WSPR / JT65 testing, I would be hard pressed to say
that much if any RF is being absorbed by the trees.

In my case, I work with what I have available.  For me, they just work.

Mike va3mw


On Mon, Nov 14, 2016 at 12:54 AM, Lee STRAHAN  wrote:

>
>
>   Greetings Top-Banders, I have been away for a couple days, sorry for the
> late comments.
> The fact is, for me there is no definitive answer to the effect of
> trees on the Hi-Z arrays. I have made tests measuring phase shifts and
> amplitude changes with a variety of objects around these elements. My
> original thoughts after the tests were that any tree or large foliage would
> have to a minimum of 5 feet distance from the elements. There are not many
> trees where I live so this sort of test is very difficult. One of the
> things I did was to measure the capacitance of the elements as a source
> impedance to the amps. Changes in this capacitance would make amplitude
> changes at the amplifiers. The only real changes I measured after numerous
> tests were when I would approach the element with the capacitance meter in
> operation. When a 6 foot person approached the elements I could see changes
> in the element at about 3 feet separation. Nothing at 5 feet. This was with
> a 24 foot aluminum element and a low capacity mounting insulator. This
> capacitance test was more sensitive than my voltage and phase measurements.
>Mike NI7T installed a 4 square system in the forest behind his cabin.
> Many pine and redwood trees were within 5 feet of the elements. We were
> never able to discern any negative affects to his array. Front to back
> rejection was well within nominal and front patterns seemed proper. The
> array remained sensitive to weak signals. Larry K1UO had his array in a
> brush patch. As I recall I suggested a 5 foot spacing which he did. If you
> have not seen the DX Larry posts from Maine you are missing something. In
> other words it was apparently adequate spacing.
>So with the 24 foot elements ¾ inch diameter that have around a 75pf
> source capacitance I would say you are pretty safe at 5 feet. Shorter
> elements with significantly less source capacitance would surely need more
> spacing. A 12 foot similar element drops clear down to 42pf source
> capacitance. I would hazard a guess that arrays using short whip elements
> at around 25pf would be quite sensitive to close trees or foliage.
> Barring all this I am confident you would be absolutely safe in my
> estimation at 10 feet distance of brush, tall foliage, and trees from the
> elements.
>
> Lee  K7TJR
>
> >>Hello Jim
>
> My HI-Z 4 square has trees about 15 feet away from two of the elements (I
> can make exact distance measurements if that would help you).
>
> I do not "think" the trees interact in my setup - but I am not 100% sure.
> Even my HI-Z 8 circle has trees pretty close to 3 elements (10 feet).
> Without measuring changes (impedance) to these elements due to location, I
> am not sure how else to know. However, given Frank's comments - I will be
> trimming some trees today!
>
> I am certain K7TJR is the expert on this has he has heard from users about
> element location and performance for years.
>
> I wish you the best.
>
> 73
> Tim K3LR
>
> 
> From: donov...@starpower.net [mailto:
> donov...@starpower.net]
> Sent: Saturday, November 12, 2016 6:57 PM
> To: j...@audiosystemsgroup.com
> Cc: Lee K7TJR; k...@k3lr.com; Joel Harrison
> Subject: Re: Hi-Z Around Trees
>
> Hi Jim,
>
> My comments about short verticals not performing well near trees
> applies only to high impedance verticals.   Low impedance are
> little affected.
>
> 73
> Frank
> W3LPL
> 
>
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> Topband Reflector Archives - http://www.contesting.com/_topband
>
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Topband: FW: Hi-Z Around Trees

[Lee STRAHAN]

  Greetings Top-Banders, I have been away for a couple days, sorry for the late 
comments.
The fact is, for me there is no definitive answer to the effect of trees on 
the Hi-Z arrays. I have made tests measuring phase shifts and amplitude changes 
with a variety of objects around these elements. My original thoughts after the 
tests were that any tree or large foliage would have to a minimum of 5 feet 
distance from the elements. There are not many trees where I live so this sort 
of test is very difficult. One of the things I did was to measure the 
capacitance of the elements as a source impedance to the amps. Changes in this 
capacitance would make amplitude changes at the amplifiers. The only real 
changes I measured after numerous tests were when I would approach the element 
with the capacitance meter in operation. When a 6 foot person approached the 
elements I could see changes in the element at about 3 feet separation. Nothing 
at 5 feet. This was with a 24 foot aluminum element and a low capacity mounting 
insulator. This capacitance test was more sensitive than my voltage and phase 
measurements.
   Mike NI7T installed a 4 square system in the forest behind his cabin. Many 
pine and redwood trees were within 5 feet of the elements. We were never able 
to discern any negative affects to his array. Front to back rejection was well 
within nominal and front patterns seemed proper. The array remained sensitive 
to weak signals. Larry K1UO had his array in a brush patch. As I recall I 
suggested a 5 foot spacing which he did. If you have not seen the DX Larry 
posts from Maine you are missing something. In other words it was apparently 
adequate spacing.
   So with the 24 foot elements ¾ inch diameter that have around a 75pf source 
capacitance I would say you are pretty safe at 5 feet. Shorter elements with 
significantly less source capacitance would surely need more spacing. A 12 foot 
similar element drops clear down to 42pf source capacitance. I would hazard a 
guess that arrays using short whip elements at around 25pf would be quite 
sensitive to close trees or foliage.
Barring all this I am confident you would be absolutely safe in my 
estimation at 10 feet distance of brush, tall foliage, and trees from the 
elements.

Lee  K7TJR

>>Hello Jim

My HI-Z 4 square has trees about 15 feet away from two of the elements (I can 
make exact distance measurements if that would help you).

I do not "think" the trees interact in my setup - but I am not 100% sure. Even 
my HI-Z 8 circle has trees pretty close to 3 elements (10 feet). Without 
measuring changes (impedance) to these elements due to location, I am not sure 
how else to know. However, given Frank's comments - I will be trimming some 
trees today!

I am certain K7TJR is the expert on this has he has heard from users about 
element location and performance for years.

I wish you the best.

73
Tim K3LR


From: donov...@starpower.net 
[mailto:donov...@starpower.net]
Sent: Saturday, November 12, 2016 6:57 PM
To: j...@audiosystemsgroup.com
Cc: Lee K7TJR; k...@k3lr.com; Joel Harrison
Subject: Re: Hi-Z Around Trees

Hi Jim,

My comments about short verticals not performing well near trees
applies only to high impedance verticals.   Low impedance are
little affected.

73
Frank
W3LPL


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