antenna clearence

systemd0wn · 08-06-2002

aight, i have about 1.3 miles of trees and crap in the way of 2 locations... :P (thanks to the guy who set this up) and i duno if we can get a taller tower or not....

WHAT IF, we were able to set up a bridge in repeater mode, and get it on someone elses TALL tower in between? and point the 2 locations antennas at the repeater? is that possible. thanks for all your help.

we should be able to make the 1.3 mile distance, after doing the math i found it should go 1.88 miles figuring cable loss, etc. and with the amp it should go like 30 some miles! but i guess the tree's are stronger.

panaph0bic · 08-06-2002

not sure if this is at all possible....but i read your location and it says ILLINOIS. .. . where? i live in WHEATON if you know where that is. let me know where you live and if at all close we can possibly do some wardriving.

mellow · 08-06-2002

ive done some reading some time ago that people had found if they turned their antennas at i think 60 degrees instead of vertical or horizontal it cut through the trees better.. i had the same problem with a tree growing up in line of site and other than cutting down the tree i couldnt do anything about it. The repeater idea is going to be an expensive solution. But it will work with an omni that the both locations would point to.

ted · 08-06-2002

Once several years ago I tested with a ham friend of mine how to utilize passive repeaters.

A passive repeater in it's simplest form is a reflector, and both ends beam to it. We did it, and, voila, we had a connection AROUND a mountain, which blocked the line-of-sight between us. We used 70 cm band rigs, but it should work on ISM, too. We tested with a metallic reflector, and also succeded to use a nearly vertical mountain side as a reflector. We had pretty long Yagis in both ends (I have forgotten how many elements and how much gain, but it is not the main point).

We also found out that horizontal polarization is better than vertical -- much better when beaming through forest, and when using a mountain side reflection.

It could be worth a try; using highly directional antennas in both ends, and either a relatively large reflector (in correct angle, it is like optics...) or possibly two directional antennaes feeding each other. (We did not test that two antenna configuration). Or, why not, if there is a tall object like a high rise buildig or water tower in a suitable position in between, just beam it, like we did with the mountain?

systemd0wn · 08-06-2002

damn ted! thats a slick idea. ive herd some about doing that kind of thing, prob. some time out of college 4 years from now, ill get my ham licence, but dont have the time to read again on it. (tried back in jr. hight, but no luck... dont think it would be a prob. now though, if i took the time to read)

anyway, their are NO tall buildings in this small town. haha. prob. a 2 or 3 story is the tallest, the trees here are taller, hah. Im not just reflecting though, and im not real sure but using the bridge in this fashion isnt considered passive repeating, is it? maybe someone can clearify that. Well, i talked to my boss and hes going to contact the owners of that tower i talked about. but first i need to see if we can even get line of sight to that.

The only thing is, is that one of the bridges now has an omni, and 1 of them is going to HAVE to be, becouse in the grand scheme their are 3 buildings.

Ill try adjusting the antenna sometime this week and see if that cuts threw the tree's. Now that i think about it, i dont know how the guy could have known exactly where to aim it in the first place with all the tree's in the way!

panaph0bic, i live about 3 - 3 1/2 hours away... perhaps some time this would be an option... it would be fun!

ted · 08-06-2002

Well, a passive repeater is -- surprise -- passive. Like a resistor or capacitor are passive cmponents. No amplification, and no power source. So an access point does not qualify to the title. It would be an active repeater. And it needs power feed as well, adding to the complications and expenses.

If you try to beam through the woods, I would try with horisontal polarization, use two good, directional high-gain antennas, and aim with a map and a compass. But, even if you some bright and dry day get the link up, it does not mean that it will work on a rainy day. Wet trees absorb signals on this band pretty well!

I think the link through/around the forest should be a dedicated point-to-point link, and it would be better to keep the omnidirectional antenna separate from that PTP link. Maybe using two access points, one for local needs and other for the "difficult link"?

If you can find that somebody's tower is visible from both buildings, try to use it as a passive repeater with two high-gain antennas. One does not need to talk with the owner in the first place--I don't think it is trespassing to beam the construction for a technical test

I think your boss might sign the purchase order for some antennas and cables to test it if there is some hope for a simple solution.

rerunn · 08-06-2002

Quote:

Originally posted by ted

A passive repeater in it's simplest form is a reflector, and both ends beam to it.

This is really interesting to me. Is that repeater simply a physical reflector -- signal hits it and ricochet's off of it?? Or is it actually taking the signal and rebroadcasting the signal in the other intended direction?

'scuse my ignorance -- This is all kinda new but Im finding it incredibly interesting.

fordem · 08-06-2002

Do a google search on passive repeaters and you'll come up with all sorts of interesting stuff - including several discussions on linking pringles cans or parabolics with LMR400 and pointing them in different directions.

I recall seeing one with actual test results but can't seem to find it again

rerunn · 08-06-2002

Quote:

Originally posted by fordem
Do a google search on passive repeaters and you'll come up with all sorts of interesting stuff

Uhh... yhea i should have known better

So from my RTFG session -- passive repeater can be as simple as two antennas linked back to back with proper cabling as can be seen here -- no electronics involved. Nice.

Check out this mother of a repeater:

edit -- sorry for the LARGE picture -- lesson well learned.

sparafina · 08-06-2002

Have you read Cringely's article on setting up repeaters?

http://www.pbs.org/cringely/pulpit/pulpit20020207.html

lincomatic · 08-06-2002

Quote:

Originally posted by sparafina
Have you read Cringely's article on setting up repeaters?

http://www.pbs.org/cringely/pulpit/pulpit20020207.html

haven't a bunch of people pretty much debunked it as a hoax?
a friend of mine who is a microwave guy thinks that a bank shot off a water tower or other large object is probably better than cringley's dual-yagi passive repeater

rerunn · 08-06-2002

Quote:

Originally posted by sparafina
Have you read Cringely's article on setting up repeaters?

http://www.pbs.org/cringely/pulpit/pulpit20020207.html

Actually, I did read that a long time ago. But I failed to realize at the time what it was

As far as the hoax thing goes.... I emailed him and asked for more details. Cant hurt right?

lincomatic · 08-06-2002

Quote:

Originally posted by rerunn

Actually, I did read that a long time ago. But I failed to realize at the time what it was

As far as the hoax thing goes.... I emailed him and asked for more details. Cant hurt right?

good luck. rob flickenger (of pringles fame) couldn't get any good info out of him.

rerunn · 08-06-2002

Found a message on the RFMON list from a Jason Lewis dated Feb 8, 2002.

Heres a snippet:

Very cool. I sent him email about the repeater and he says that it is
identical to this one.

http://www.netscum.com/~clapp/wireless.html

All we really need is passive repeaters in high trees!!

jas

lincomatic · 08-06-2002

here is flickenger's analysis of cringe's passive repeater:

http://www.oreillynet.com/cs/user/view/wlg/1124

08-06-2002	#1 (permalink)
systemd0wn Probematic Stumbler Join Date: Apr 2002 Location: Illinois Posts: 153	antenna clearence aight, i have about 1.3 miles of trees and crap in the way of 2 locations... :P (thanks to the guy who set this up) and i duno if we can get a taller tower or not.... WHAT IF, we were able to set up a bridge in repeater mode, and get it on someone elses TALL tower in between? and point the 2 locations antennas at the repeater? is that possible. thanks for all your help. we should be able to make the 1.3 mile distance, after doing the math i found it should go 1.88 miles figuring cable loss, etc. and with the amp it should go like 30 some miles! but i guess the tree's are stronger. __________________ Systemd0wn '311 Transistor, its a lightning resistor'

08-06-2002	#5 (permalink)
systemd0wn Probematic Stumbler Join Date: Apr 2002 Location: Illinois Posts: 153	damn ted! thats a slick idea. ive herd some about doing that kind of thing, prob. some time out of college 4 years from now, ill get my ham licence, but dont have the time to read again on it. (tried back in jr. hight, but no luck... dont think it would be a prob. now though, if i took the time to read) anyway, their are NO tall buildings in this small town. haha. prob. a 2 or 3 story is the tallest, the trees here are taller, hah. Im not just reflecting though, and im not real sure but using the bridge in this fashion isnt considered passive repeating, is it? maybe someone can clearify that. Well, i talked to my boss and hes going to contact the owners of that tower i talked about. but first i need to see if we can even get line of sight to that. The only thing is, is that one of the bridges now has an omni, and 1 of them is going to HAVE to be, becouse in the grand scheme their are 3 buildings. Ill try adjusting the antenna sometime this week and see if that cuts threw the tree's. Now that i think about it, i dont know how the guy could have known exactly where to aim it in the first place with all the tree's in the way! panaph0bic, i live about 3 - 3 1/2 hours away... perhaps some time this would be an option... it would be fun! __________________ Systemd0wn '311 Transistor, its a lightning resistor'

08-06-2002	#14 (permalink)
rerunn rerunn run run Join Date: Jun 2002 Location: way up north Posts: 70	More on cringely Found a message on the RFMON list from a Jason Lewis dated Feb 8, 2002. Heres a snippet: Very cool. I sent him email about the repeater and he says that it is identical to this one. http://www.netscum.com/~clapp/wireless.html All we really need is passive repeaters in high trees!! jas

08-06-2002	#15 (permalink)
lincomatic Squaaawk! WiFi! WiFi! Join Date: Apr 2002 Location: Tinsel Town Posts: 1,682	flickenger's test here is flickenger's analysis of cringe's passive repeater: http://www.oreillynet.com/cs/user/view/wlg/1124

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08-06-2002	#2 (permalink)
panaph0bic Registered Member Join Date: Jul 2002 Posts: 11	not sure if this is at all possible....but i read your location and it says ILLINOIS. .. . where? i live in WHEATON if you know where that is. let me know where you live and if at all close we can possibly do some wardriving.

08-06-2002	#3 (permalink)
mellow Registered Member Join Date: Jul 2002 Posts: 20	ive done some reading some time ago that people had found if they turned their antennas at i think 60 degrees instead of vertical or horizontal it cut through the trees better.. i had the same problem with a tree growing up in line of site and other than cutting down the tree i couldnt do anything about it. The repeater idea is going to be an expensive solution. But it will work with an omni that the both locations would point to.

08-06-2002	#4 (permalink)
ted Stumbling on Join Date: Aug 2002 Location: Houston,TX Posts: 47	Once several years ago I tested with a ham friend of mine how to utilize passive repeaters. A passive repeater in it's simplest form is a reflector, and both ends beam to it. We did it, and, voila, we had a connection AROUND a mountain, which blocked the line-of-sight between us. We used 70 cm band rigs, but it should work on ISM, too. We tested with a metallic reflector, and also succeded to use a nearly vertical mountain side as a reflector. We had pretty long Yagis in both ends (I have forgotten how many elements and how much gain, but it is not the main point). We also found out that horizontal polarization is better than vertical -- much better when beaming through forest, and when using a mountain side reflection. It could be worth a try; using highly directional antennas in both ends, and either a relatively large reflector (in correct angle, it is like optics...) or possibly two directional antennaes feeding each other. (We did not test that two antenna configuration). Or, why not, if there is a tall object like a high rise buildig or water tower in a suitable position in between, just beam it, like we did with the mountain?

08-06-2002	#6 (permalink)
ted Stumbling on Join Date: Aug 2002 Location: Houston,TX Posts: 47	Well, a passive repeater is -- surprise -- passive. Like a resistor or capacitor are passive cmponents. No amplification, and no power source. So an access point does not qualify to the title. It would be an active repeater. And it needs power feed as well, adding to the complications and expenses. If you try to beam through the woods, I would try with horisontal polarization, use two good, directional high-gain antennas, and aim with a map and a compass. But, even if you some bright and dry day get the link up, it does not mean that it will work on a rainy day. Wet trees absorb signals on this band pretty well! I think the link through/around the forest should be a dedicated point-to-point link, and it would be better to keep the omnidirectional antenna separate from that PTP link. Maybe using two access points, one for local needs and other for the "difficult link"? If you can find that somebody's tower is visible from both buildings, try to use it as a passive repeater with two high-gain antennas. One does not need to talk with the owner in the first place--I don't think it is trespassing to beam the construction for a technical test I think your boss might sign the purchase order for some antennas and cables to test it if there is some hope for a simple solution.

08-06-2002	#8 (permalink)
fordem Tropical Stumbler Join Date: Apr 2002 Posts: 575	Do a google search on passive repeaters and you'll come up with all sorts of interesting stuff - including several discussions on linking pringles cans or parabolics with LMR400 and pointing them in different directions. I recall seeing one with actual test results but can't seem to find it again

08-06-2002	#10 (permalink)
sparafina Registered Member Join Date: May 2002 Location: TX,MD,NY Posts: 1,431	Have you read Cringely's article on setting up repeaters? http://www.pbs.org/cringely/pulpit/pulpit20020207.html