I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

'Captain' Kirk DeHaan wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

Wait for winter and use a beam antenna to locate the tree(s) that need to be
trimmed.

If a 10 element beam won't "blast" through the trees in the summer, it should
get you down to a line of 1 or two trees that need to be cut.

A more radio oriented project would be to put a 6m or 10m input on the
repeater. 10m should groundwave over the trees anyway. It's easy enough to
test.

10m inputs are IMHO neat, at the top of the sunspot cycle, they give your
repeater worldwide input. At that point a 10m output would be good too, but
for now, it's not much of a problem.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
It's amazing how many people have no clue what the word "contiguous" means. :-(

On Sun, 22 May 2011 18:29:03 +0000 (UTC), Geoffrey S. Mendelson wrote:

10m inputs are IMHO neat, at the top of the sunspot cycle,
they give your repeater worldwide input.

s/input/QRM/

On 22 mayo, 20:04, 'Captain' Kirk DeHaan
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. *It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. *I would have a
line of sight if not for the trees as I'm up enough in altitude. *I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. *Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? *I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

Hello,

The repeater antenna will probably have most of its radiation in the
horizontal plane and 145 MHz is far above the critical frequency, so
your rays will leave earth.

Did you monitor the signal for several time (also winter and rain) to
assess the real influence of the trees? Do you have any possibility to
move the J-pole to another place?

As you can open the repeater now and then, some 10 dB additional gain
will certainly help you to get above the FM-knee (assuming that you
can get the beam at same height as the J-pole. Nice thing is, it will
also improve reception.

With kind regards,

Wim
PA3DJS
www.tetech.nl
remove abc first in case of PM

On May 22, 11:04*am, 'Captain' Kirk DeHaan
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. *It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. *I would have a
line of sight if not for the trees as I'm up enough in altitude. *I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. *Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? *I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

I can't see that NVIS has any VHF backers.

Can you exploit Google Maps, satellite view, to establish a precise
line bearing from your antenna to the repeater site? If you need even
more help than you get from your new yagi, then such a line bearing
will help identify your "trouble trees."

I had to do it for a new FD site a few years ago. We're in San Diego
and I wanted to work 2m into Los Angeles. First, I used a protractor
to determine LA was X-degrees True (whatever it was) from us; next, on
a close-up print of the FD site, I plotted that same line bearing from
the antenna site to obvious local landmarks which we then used on the
the ground for pointing the 2m beam.

This is not the only approach, but it got me what I needed.

"Sal"
(KD6VKW)

On 5/22/2011 3:11 PM, Sal M. Onella wrote:
On May 22, 11:04 am, 'Captain' Kirk
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

I can't see that NVIS has any VHF backers.

Can you exploit Google Maps, satellite view, to establish a precise
line bearing from your antenna to the repeater site? If you need even
more help than you get from your new yagi, then such a line bearing
will help identify your "trouble trees."

I had to do it for a new FD site a few years ago. We're in San Diego
and I wanted to work 2m into Los Angeles. First, I used a protractor
to determine LA was X-degrees True (whatever it was) from us; next, on
a close-up print of the FD site, I plotted that same line bearing from
the antenna site to obvious local landmarks which we then used on the
the ground for pointing the 2m beam.


For this kind of thing "RadioMobile" from VE2DBE is the application of
choice. It will load the SRTM terrain DEMs, etc. and plot out the path
quite nicely.
http://www.cplus.org/rmw/english1.html


But, if you can get in sometimes, but not others, the next question is,
"can you hear it"?

How long is your coax?
If more than 20 ft, are you running a preamp?

Getting 10-15 dB gain over a jpole would be easy with a moderate length
Yagi. A M2 2M4 (4 elements, $115) is about 10dBi. A 2M9($240) is about
14dBi

On 5/22/2011 1:04 PM, 'Captain' Kirk DeHaan wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I have
a lot of trees, mostly poplars, in the direct path. I would have a line
of sight if not for the trees as I'm up enough in altitude. I can cut
the trees, they're mine, but finding the right ones is difficult and i
don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it being
applied in HF.

'Captain' Kirk DeHaan
N6SXR

Your yagi may fix your problem completely. Other things to consider:

* Try moving your existing antenna. Even a small movement may cure the
problem as you may have cancelling reflections at times. There is almost
always a "sweet spot" somewhere in the vicinity.

* Try tilting your antenna to 45 degrees and see if that helps. It might
improve reception due to the random polarization of the incoming signal
caused by the trees.

Note: do this on a day when the signal is either weak or non-existent.
You can always apologize for kerchunking. Or, use your S-meter if you
have one.

Cheers & Good Luck,
John
KD5YI

On Sun, 22 May 2011 17:55:16 -0500, John KD5YI
wrote:

* Try moving your existing antenna. Even a small movement may cure the
problem as you may have cancelling reflections at times. There is almost
always a "sweet spot" somewhere in the vicinity.

I beg to differ. I have about 30 years experience in dealing with
propogation through a dense redwood forest (Ben Lomond CA). The trees
in my area are about 120ft high. While moving the antenna around may
temporarily improve the signal quality by reducing frequency selective
fading, multipath, reflections, and just plain bad luck, they do not
tend to remain improved. Trees grow and move around. What works well
now, will probably not work well tomorrow.

I gave up on fixed antenna mounts for my rooftop verticals. (Well, I
have one mounted on a tripod, but that was before I realized what was
happening). Most of my verticals are mounted on 2x12 planks, held
down to the roof with sand bags, concrete blocks, and buckets full of
water. Every few months, I move the antennas around to see if I can
improve the signals to specific repeaters.

* Try tilting your antenna to 45 degrees and see if that helps. It might
improve reception due to the random polarization of the incoming signal
caused by the trees.

I beg to differ again. Tree trunks are mostly water and do an
impressive job of simulating a slot type polarization filter at 2m and
440Mhz frequencies. Leaves and branches will pass RF fairly well, but
not tree trunks. I've played with both polarizations, circular
polarization:
http://802.11junk.com/jeffl/circular-polarization/
and some diversity reception. Empirically, signals are about 6dB
stronger going through the trees vertically polarized, than
horizontal. The effect continues up to at least 2.4GHz. Above that,
at 5.7GHz, the signals seem to be going through the holes between the
leaves.

I must admit that I haven't actually tried 45 degrees on 2m or 440Mhz,
but I don't think it will help much. Still, it's an easy thing to
try.

Note: do this on a day when the signal is either weak or non-existent.
You can always apologize for kerchunking. Or, use your S-meter if you
have one.

Do it on a windy day, when the trees are moving around, so you can see
how much it will change.

Cheers & Good Luck,
John
KD5YI

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 5/22/2011 8:26 PM, Jeff Liebermann wrote:
On Sun, 22 May 2011 17:55:16 -0500, John
wrote:

* Try moving your existing antenna. Even a small movement may cure the
problem as you may have cancelling reflections at times. There is almost
always a "sweet spot" somewhere in the vicinity.

I beg to differ. I have about 30 years experience in dealing with
propogation through a dense redwood forest (Ben Lomond CA). The trees
in my area are about 120ft high. While moving the antenna around may
temporarily improve the signal quality by reducing frequency selective
fading, multipath, reflections, and just plain bad luck, they do not
tend to remain improved. Trees grow and move around. What works well
now, will probably not work well tomorrow.

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

I gave up on fixed antenna mounts for my rooftop verticals. (Well, I
have one mounted on a tripod, but that was before I realized what was
happening). Most of my verticals are mounted on 2x12 planks, held
down to the roof with sand bags, concrete blocks, and buckets full of
water. Every few months, I move the antennas around to see if I can
improve the signals to specific repeaters.

Good for you! Pat yourself on the back.

* Try tilting your antenna to 45 degrees and see if that helps. It might
improve reception due to the random polarization of the incoming signal
caused by the trees.

I beg to differ again. Tree trunks are mostly water and do an
impressive job of simulating a slot type polarization filter at 2m and
440Mhz frequencies. Leaves and branches will pass RF fairly well, but
not tree trunks. I've played with both polarizations, circular
polarization:
http://802.11junk.com/jeffl/circular-polarization/
and some diversity reception. Empirically, signals are about 6dB
stronger going through the trees vertically polarized, than
horizontal. The effect continues up to at least 2.4GHz. Above that,
at 5.7GHz, the signals seem to be going through the holes between the
leaves.

I must admit that I haven't actually tried 45 degrees on 2m or 440Mhz,
but I don't think it will help much. Still, it's an easy thing to
try.

You spent more words debunking the suggestion than admitting that you
don't really know whether it could help or not. Good move. And, by the
way, I have experience to the contrary at both 144 and 444 MHz. It all
depends on the location of the source and the receiver. At 2 meters,
some rotation of the antenna can sometimes be helpful. Note that we are
not concerned with GHz.

John

On Sun, 22 May 2011 20:56:52 -0500, John KD5YI
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

30 years of trying to maintain a stable signal to several distant
repeaters is sufficient to convince me. Trees move and grow, causing
signals to change.

Also, temporary is a rather useless term. In my experience, if it
works, it's permanent.

Good for you! Pat yourself on the back.

Thank you for the traditional contentious remark.

You spent more words debunking the suggestion than admitting that you
don't really know whether it could help or not.

True. I spent more words explaining why I suspect it will not work,
what I expect will happen, and a bit of substantiation. I consider
this a substantial improvement over the traditional one-line
pontification.

Good move. And, by the
way, I have experience to the contrary at both 144 and 444 MHz. It all
depends on the location of the source and the receiver. At 2 meters,
some rotation of the antenna can sometimes be helpful.

Perhaps it would be helpful if you read what I had written. I said
that rotating the antenna might help temporarily, but that movements
of the trees, tree growth, swaying branches in the wind, and possibly
sources of reflections, will soon negate any temporary benefits. If
the yagi is going to arrive shortly, then tilting the antenna is
probably a useful exercise.

Note that we are not concerned with GHz.

Topic drift follows:
Since you mentioned GHz, one of the other problems with living in the
deep dark forest is that DBS satellite dish reception is a problem. I
hacked an 8ft diameter hole in the tree canopy by lopping off some
branches at about the 80ft level, through which I point my DirecTV
dish. Every year, the trees grow a little, requiring that I move the
dish around my roof. During the twice annual solar satellite outage:
http://en.wikipedia.org/wiki/Sun_outage
Twice a year, I photograph the sunlight shining through the hole and
onto the dish and roof. If there are shadows of branches on the dish,
I move it to a better location.
http://www.11junk.com/jeffl/pics/DBS/
Note the shadow at 12 o'clock on the dish.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558