Long Range Wifi

[DonRotolo]

Yagis at both ends will give you plenty of link margin if it is only trees. I fear you are really hitting up against the speed of light.

WiFi has some very tight send-and-respond timing, particularly at high throughput. 1.1 km is a significant fraction of the ultimate limit for 802.11 distance, specifically because of the time it takes for the signal to travel - at the speed of light.

Oh, and your dish-on-a-pole-on-a-tower will come down in the first or second ice storm - you get those in PA, right? Don't ask how I know.

Oh, and what Al said about trees. (But, perversely, although a tree WILL grow, your antenna won't get any higher off the ground as it does).

I encourage you to learn about WiFi link timing and do the math for 1.1 km. You will be surprised at how tenuous that link is, but not for signal strength. Try 802.16 instead, built exactly for what you want to do.

[Scott L.]

Originally Posted by DonRotolo

Yagis at both ends will give you plenty of link margin if it is only trees. I fear you are really hitting up against the speed of light.

WiFi has some very tight send-and-respond timing, particularly at high throughput. 1.1 km is a significant fraction of the ultimate limit for 802.11 distance, specifically because of the time it takes for the signal to travel - at the speed of light.

Oh, and your dish-on-a-pole-on-a-tower will come down in the first or second ice storm - you get those in PA, right? Don't ask how I know.

Oh, and what Al said about trees. (But, perversely, although a tree WILL grow, your antenna won't get any higher off the ground as it does).

I encourage you to learn about WiFi link timing and do the math for 1.1 km. You will be surprised at how tenuous that link is, but not for signal strength. Try 802.16 instead, built exactly for what you want to do.

https://dl.ubnt.com/datasheets/Power...Beam5ac_DS.pdf

The dishes are the PBE-5AC-500. 5.8GHZ Carrier using 80MHz channel.
Light travels 300,000km/s, so a 1.1km distance would take 3.67uS one way
Tower is a rohn 25G series.
21'pipe is 1-1/4" ID with 1.66"OD

[gblake]

Originally Posted by Scott L.

https://dl.ubnt.com/datasheets/Power...Beam5ac_DS.pdf

The dishes are the PBE-5AC-500. 5.8GHZ Carrier using 80MHz channel.
Light travels 300,000km/s, so a 1.1km distance would take 3.67uS one way
Tower is a rohn 25G series.
21'pipe is 1-1/4" ID with 1.66"OD

If you do have any doubts about your expected throughput, and if you already have the equipment, take it to the two sides of an easily accessible 1.1km wide unobstructed "valley", and then see how much throughput you can get. That will put an upper bound on what you can try to achieve shooting through the trees.

In the same vein, attach some weight lifting weights to the pole to represent your equipment, plus ice & snow, then mount the pole on something sturdy (at ground level), then pull hard on its top with a rope to mimic a strong wind. See what happens (be out of the way if anything breaks loose).

For the weight and wind loadng test, if you can attach the pole to something at ground level using the same brackets you want to use to lock it in place up in the air, even better. See how they hold up when you abuse them.

[bdaroz]

Not wanting to derail Scott's question, but much along the same lines...

Any suggestions or ideas on a ~750' run thru some trees and the tops of 2-3 houses?

I could try to elevate but that would only get me away from maybe 2 of the houses, trees would still be in the way.

[DonRotolo]

OK, one thing is that it boasts "automatic distance selection (ACK Timing)" so my comments about lightspeed are somewhat less relevant.

The spec for the 500 also calls for a 60 lb wind loading force at 60 MPH. Your 6061 aluminum pipe (nominal 1.25" Sch 80) yields at 24000 lbs, you have a Section Modulus of 0.291 cuin. Bending stress at the bottom of the 18' pole is (60 lb x 216 in) / .291 = 44,536 psi which is nearly double the pipe's strength - it'll bend long before 60 MPH is seen. Source (pdf)

And I still thing you're underestimating the effects of tree sway. The 3 dB beamwidth is shown as about 5 degrees, which is pretty tight (but typical for a dish, or a Yagi with comparable gain), wobble will kill your performance.

I don't disagree you need to get above the trees.

[gblake]

Don - The OP says the pipe is galvanized steel - Blake

[DonRotolo]

Ah, missed that. Steel should be OK, at about 54k. Thanks Blake.

750 feet through the trees: The lower the frequency, the less the trees matter. So 2.4 GHz is better than 5 GHz, 900 MHz even better. Not sure there's a good commercial solution below that. Even 440 MHz is affected, while 150 hardly at all.
No chance you could run some Ethernet, is there? drainage culverts sometimes offer a solution to cross streets...

[gblake]

Originally Posted by DonRotolo

Ah, missed that. Steel should be OK, at about 54k. Thanks Blake.

750 feet through the trees: The lower the frequency, the less the trees matter. So 2.4 GHz is better than 5 GHz, 900 MHz even better. Not sure there's a good commercial solution below that. Even 440 MHz is affected, while 150 hardly at all.
No chance you could run some Ethernet, is there? drainage culverts sometimes offer a solution to cross streets...

Yep, just don't ask me to be one of the poor saps who has to lug a steel pipe, plus the payload, up that 60' tower; and then hold the pipe & payload upright and aloft to attach it to the tower.

That's not a desk job. I'll create the drawings, if someone else will do the climbing .

[Scott L.]

Originally Posted by gblake

Yep, just don't ask me to be one of the poor saps who has to lug a steel pipe, plus the payload, up that 60' tower; and then hold the pipe & payload upright and aloft to attach it to the tower.

That's not a desk job. I'll create the drawings, if someone else will do the climbing .

I raised the pipe using ropes, and a jin pole, same with the dish and the top tower section comes to a point with a mast bushing in its center. So the pipe was raised, than lowered through the bushing, dish was attached and the whole assembly was raised back up. I was securely attached to the tower with my work at heights harness.

As for the 750' culverts are the way to cross streets, if used I would run the cable through 1/2" black water line to help protect it. as for the 100m ethernet limitation, a poe extender solves that

http://www.bhphotovideo.com/c/produc...x_Outdoor.html

[Al Skierkiewicz]

Scott,
Sorry but work got in the way of responding. I have to weigh in on the pipe moving around. We have ours mounted on 4" galvanized pipe and it is only 10 feet high (roof mounted) to keep the patterns aligned. Mounting another dish on a tree flexes even more that a small pipe. With both the tower and the tree moving around and twisting, it is very likely that the dishes will pull out of alignment on a regular basis that will be nearly impossible to compensate with a moving dish.
A system to aim antennas real time, requires some method to determine the direction of the move and magnitude. I have seen this done with a system that "wobbles" the device so that a feedback mechanism can detect both direction and magnitude. You would not want to due that with a dish for mechanical stress. You could move the feed horn which is a much smaller mass but it may not give you the range needed.
As to trees in the fresnel zone, if they were simply into the zone and not obstructing it, the path loss would seem to overcome the phase rotation introduced by the leaves. However, I think the trees are likely obstructing the path and you have significant path loss that this dish pair cannot overcome. Just running a quick path loss calc it looks like you could easily have 80 dB loss without the trees with this dish pair. I would bet that the tress introduce a variable or between 20 and 40 dB additional loss. That eats all of your available margin. The only way to overcome path loss is to increase transmit power, receiver gain or antenna gain(size). With the antennas you are using, none of those are possible. Even going to the 620 antenna only gets you another 2dBi. I think you have to pick up another 10-20dB of gain.
For my money, a larger antenna mounted on the tower and not a pipe is preferred. I can speak to leaves being a significant attenuator at 450 MHz. Many digital broadcast stations are finding that antenna placement for our viewers need to be away from trees. Many folks who had no problem with reception of our high VHF station in the past, have issues on our Ch47 (660MHz) UHF digital station. When it rains, data loss is significant to the point of no reception at all.