Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle
Trees cause real attenuation on both 2M and 70cm. Near field effects are more pronounced that far field.
It's not a hobby killer but it will degrade your performance.
Trees are a hobby killer for EME on 2M and above.
73 - Paul - W2HRO
On Fri, Sep 14, 2018, 16:46 Bob- W7LRD w7lrd@comcast.net wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Trees with wet leafs on them tend to gobble up UHF uplinks. It’s not quite as bad on VHF but can have an affect.
Jeff WE4B
On Sep 14, 2018, at 3:51 PM, Paul Andrews w2hro.fn20@gmail.com wrote:
Trees cause real attenuation on both 2M and 70cm. Near field effects are more pronounced that far field.
It's not a hobby killer but it will degrade your performance.
Trees are a hobby killer for EME on 2M and above.
73 - Paul - W2HRO
On Fri, Sep 14, 2018, 16:46 Bob- W7LRD w7lrd@comcast.net wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
If you are working with 5w into a handheld Yagi trees + leaves are rough. Running +50w into huge yagis with preamps they probably do not matter too much on 2m/70cm, above that and they certainly will.
Different answer for different operating conditions.
73, Don KB2YSI
On Fri, Sep 14, 2018, 18:51 Jeff Johns jeff30339@gmail.com wrote:
Trees with wet leafs on them tend to gobble up UHF uplinks. It’s not quite as bad on VHF but can have an affect.
Jeff WE4B
On Sep 14, 2018, at 3:51 PM, Paul Andrews w2hro.fn20@gmail.com wrote:
Trees cause real attenuation on both 2M and 70cm. Near field effects are more pronounced that far field.
It's not a hobby killer but it will degrade your performance.
Trees are a hobby killer for EME on 2M and above.
73 - Paul - W2HRO
On Fri, Sep 14, 2018, 16:46 Bob- W7LRD w7lrd@comcast.net wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Leaves on trees a make a difference for me.
I call it “Arboreal QSB”.
One advantage of portable ops is that you can move away from the Arboreal QSB.
-- bag
Bryan KL7CN/W6 bryan@kl7cn.net
On Sep 14, 2018, at 13:45, Bob- W7LRD w7lrd@comcast.net wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Hi Bob,
Trees probably do have an effect, but unlike others, I've not found it to be a significant problem. At least, not one where I need to plan my passes around which trees might be in the way. The only time they did was with AO-40, where transmitting on 70cm directly into a huge oak tree would have the signal bounce back and interfere with the 2.4 ghz downlink. One could map out where the limbs were based on the results.
In an area of the country where shade in the summer is prized more than many other things, taking a chain saw to a heritage-sized oak tree in pursuit of a QSO just wasn't an option. So, AO-40 contacts to the south-east never happened. Then "unintended chemistry experiments in space" made it no longer relevant. {sniff} The only issue I have with the trees now is to keep them trimmed appropriately so they don't snag the antennas as they swing round.
Greg KO6TH
Bob- W7LRD wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Well said, Greg -- to clarify my original comments:
1. Arboreal QSB is real, but... 2. It's not that significant. 3. Switching polarity helps quite a bit.
I really only notice it when operating FO-29 on passes during the height of the Spring when the leaves seem to have the most moisture.
Otherwise, it's not a general concern. But it is fun to say "Arboreal QSB".
-- bag
Bryan KL7CN/W6 Location: CM98, usually E-Mail: bryan@KL7CN.net Telephone/SMS: 408-836-7279
On Sep 14, 2018, at 14:13, Greg D ko6th.greg@gmail.com wrote:
Hi Bob,
Trees probably do have an effect, but unlike others, I've not found it to be a significant problem. At least, not one where I need to plan my passes around which trees might be in the way. The only time they did was with AO-40, where transmitting on 70cm directly into a huge oak tree would have the signal bounce back and interfere with the 2.4 ghz downlink. One could map out where the limbs were based on the results.
In an area of the country where shade in the summer is prized more than many other things, taking a chain saw to a heritage-sized oak tree in pursuit of a QSO just wasn't an option. So, AO-40 contacts to the south-east never happened. Then "unintended chemistry experiments in space" made it no longer relevant. {sniff} The only issue I have with the trees now is to keep them trimmed appropriately so they don't snag the antennas as they swing round.
Greg KO6TH
Bob- W7LRD wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Agreed!
Good point about polarity choices. It's kind of interesting to consider the diffraction effects that large, long hunks of wet wood might have on a 70cm signal. Probably less so on 2m, given the wavelength.
Oh, I forgot to mention that green wood is pretty much a killer on 2.4 ghz. Think of what makes your microwave oven work. I suspect, but have not tried it yet, that the 1.2 ghz uplink to AO-92 on weekends might be affected if you don't have a lot of power to start with.
For some time, a bunch of years ago, our home internet was delivered via a commercial Wi-Fi-based service. I was a bit of a test subject, being on the fringe needing to burn a bit of an RF hole through yet more of our dear oak trees. What was interesting was that the presence of rain didn't make much of a difference on that band. Wood, wet or "dry" still absorbed signal quite well, and as the trees grew over time, the signal degraded to the point of stopping service. Fortunately, the cable internet folks came through about the same time and we switched.
So there is a point, somewhere between 70cm and 13 cm, where trees become a crippling factor. Below that, they're mostly just shade.
Greg KO6TH
Bryan KL7CN wrote:
Well said, Greg -- to clarify my original comments:
- Arboreal QSB is real, but...
- It's not that significant.
- Switching polarity helps quite a bit.
I really only notice it when operating FO-29 on passes during the height of the Spring when the leaves seem to have the most moisture.
Otherwise, it's not a general concern. But it is fun to say "Arboreal QSB".
-- bag
Bryan KL7CN/W6 Location: CM98, usually E-Mail: bryan@KL7CN.net Telephone/SMS: 408-836-7279
On Sep 14, 2018, at 14:13, Greg D ko6th.greg@gmail.com wrote:
Hi Bob,
Trees probably do have an effect, but unlike others, I've not found it to be a significant problem. At least, not one where I need to plan my passes around which trees might be in the way. The only time they did was with AO-40, where transmitting on 70cm directly into a huge oak tree would have the signal bounce back and interfere with the 2.4 ghz downlink. One could map out where the limbs were based on the results.
In an area of the country where shade in the summer is prized more than many other things, taking a chain saw to a heritage-sized oak tree in pursuit of a QSO just wasn't an option. So, AO-40 contacts to the south-east never happened. Then "unintended chemistry experiments in space" made it no longer relevant. {sniff} The only issue I have with the trees now is to keep them trimmed appropriately so they don't snag the antennas as they swing round.
Greg KO6TH
Bob- W7LRD wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
As some brilliant person once said “ best amplifier I ever bought was a chain saw”.
Ed Krome K9EK
Sent from my iPhone
On Sep 14, 2018, at 5:21 PM, Bryan KL7CN bryan@kl7cn.net wrote:
Well said, Greg -- to clarify my original comments:
- Arboreal QSB is real, but...
- It's not that significant.
- Switching polarity helps quite a bit.
I really only notice it when operating FO-29 on passes during the height of the Spring when the leaves seem to have the most moisture.
Otherwise, it's not a general concern. But it is fun to say "Arboreal QSB".
-- bag
Bryan KL7CN/W6 Location: CM98, usually E-Mail: bryan@KL7CN.net Telephone/SMS: 408-836-7279
On Sep 14, 2018, at 14:13, Greg D ko6th.greg@gmail.com wrote:
Hi Bob,
Trees probably do have an effect, but unlike others, I've not found it to be a significant problem. At least, not one where I need to plan my passes around which trees might be in the way. The only time they did was with AO-40, where transmitting on 70cm directly into a huge oak tree would have the signal bounce back and interfere with the 2.4 ghz downlink. One could map out where the limbs were based on the results.
In an area of the country where shade in the summer is prized more than many other things, taking a chain saw to a heritage-sized oak tree in pursuit of a QSO just wasn't an option. So, AO-40 contacts to the south-east never happened. Then "unintended chemistry experiments in space" made it no longer relevant. {sniff} The only issue I have with the trees now is to keep them trimmed appropriately so they don't snag the antennas as they swing round.
Greg KO6TH
Bob- W7LRD wrote:
Hi All- Just wondering-in the real world how much attenuation is there with trees? I am surrounded with fir trees, a huge maple tree and cedar tree, (I live in the north west). I run a IC-910, preamps at the cp yagis.
73 Bob W7LRD
Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (8)
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Bob- W7LRD -
Bryan Green -
Bryan KL7CN
-
Don KB2YSI -
Ed Krome -
Greg D -
Jeff Johns -
Paul Andrews