thewildthang
join:2005-12-21
Winfield, AL
| Horizontally Polarized Laptop
I hope that subject title will get everyone to read this post so that someone can help me with this problem.
I'm attempting to get a hot spot up but I've run into a little problem. My AP antenna is on top of a 136 ft water tank, it is a 120 deg sector tilted down toward a truck stop parking lot. The parking lot is about 200 yards away. On the lap top I get a 68% signal with the site survey but it will not link, however if I turn the lap top up on it's side it gets a 90% signal and 90% link quality. As long as you leave it turned up on its side it maintains that signal but as you tilt the laptop back to level the signal steadily declines and then it looses the link.
I'm wondering if the sector antenna was improperly labeled and it's actually a horizontal antenna? Any ideas or suggestions would be appreciated. I don't think I'll be able to get my customers to use their computer sitting on it's side. |
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viperm
Carpe Diem
Premium
join:2002-07-09
Winchester, CA
| Sounds like the ant in the laptop is horizontal to me. Usually the monitor is longer across the top then the sides in most laptops leaving me to guess the ran the ant on the top edge causing it to be H pol in stead of up the sides which to me would be vertical? I am only guessing. But then again what happens when you use a PCMCIA card the ant is usually in the card sitting flat or in H pol?
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ComTrain Certified Tower Climber. American Tower Certified approved contractor |
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PersComp
Premium
join:2005-08-17
Cayce, SC
1 edit | reply to thewildthang
Just curious...
What brand of LT and age? From what I understand, some of the earlier designs didn't think the antenna location out very well. It is quite possible that it is horizontal. Most now use antennas that run inside the monitor panel to create the vertical polarity.
When I use my wife's Dell inside my house and 50' directly underneath my AP, I usually have to tilt the screen way back so that it kind of aims into the air.
edit:After reading viperm's comment about the pcmcia cards, I thought I would mention that I bought a couple of old Cisco cards (300 series, I think) off of ebay (I don't see any of them on there now, or would have sent you a link) that have the tiny rubber duck antennas on the end to help with the V/H issues. If you want a more directional device then these work great, but get some bad publicity about being fragile.
»www.newegg.com/Product/Product.a···33164012
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Every dog has his day, but good dogs have two! |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
Actually I'm using a dlink wireless card. Rather than solving the problem for me personally I need to solve it for everybody since I will seldom if ever be using the hot spot myself. I bought this off the shelf card figuring that it would be typical of what a customer may use. |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
 ·CenturyLink
| reply to thewildthang
You might consider hanging another AP on a different channel with an HPOL panel antenna...
Another thing to consider is that the truckers are most probably using their laptops inside their sleepers and the signal they are getting almost has a "random" polarization after a few bounces.
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A is A |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
One question that I meant to ask for those who have experience with hot spots, am I being a little ambitious in expecting this thing to work from 600 ft away and 136 feet up? The 120 degree sector is aimed down at the parking lot. We're using an SR2 which means that we have plenty of available power for reaching the parking lot however the lap tops still have to be able to talk back to the AP. |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Antenna gain is more important than AP radio power in this case. Antenna gain works for both transmit AND receive, whereas AP radio output power does nothing for the receive side of the equation.
What is the gain of your sector?
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A is A |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
John,
It's the 16 db 120 deg 2.4 sector sold by Wisp Router. Looking at the antenna, the only way to tell what it is suppose to be is by reading the paper sticker affixed to the outside of the antenna housing, which is very poor by the way, the darn thing has been up less than a month and you can barely make out what it says. I also have two 120 deg horizontal 5.8 antenna and they have the exact same housing. I "ASSUME" that the antenna is as labeled. Right now my plan is to use an SR2 as a client radio with a grid antenna from some distance away and see what effect turning the grid horizontal vs vertical has, but back to the question: Am I being too ambitious expecting this thing to work at this distance using this antenna set up? |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| said by thewildthang  : Am I being too ambitious expecting this thing to work at this distance using this antenna set up? No...if you keep in mind that you need "ears" to hear the "weaky-squeaky" laptops.
I think that all would agree that 600 feet is not too very far away...
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A is A |
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lutful
Premium
join:2005-06-16
Ottawa, ON
| reply to thewildthang
said by thewildthang :Am I being too ambitious expecting this thing to work at this distance using this antenna set up? IMHO, it is the fault of classic antenna designs rather than your expectation. When I use Superpass 5Ghz sectors I always match exact polarization.
I have experimented a lot with commercial 2.4Ghz choices and now use only our own experimental moderate-gain omni and sector antennas. They work for both polarizations reasonably well and I have connected with laptop at 3000ft and PDA at 1000ft.
The basic "3-ear rabbit" polarization insensitive antenna design can be traced back to 1960s but these guys have improved it a lot.
»www.publicaffairs.ubc.ca/ubcrepo···nna.html |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
Thanks lutful for that link, interesting article. Ok, I won't think twice about purchasing a new antenna and replacing the one in question. Someone, anyone, everyone, tell me which one to purchase. Oh, and lutful, is that 1000 ft using a directional antenna or is that with an omni? |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to thewildthang
Here are some pics that I took during a recent trip from Kansas to Oregon.
The one on the pole covered an entire interchange...there was truck parking for a 1/4 mile around the AP. Signs indicated that wifi was available and there was no other AP to be seen.
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A is A |
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lutful
Premium
join:2005-06-16
Ottawa, ON
| reply to thewildthang
said by thewildthang :lutful, is that 1000 ft using a directional antenna or is that with an omni? Using the ~3dBi omni, 200mW AP and visual LOS to laptop/PDA. With a 120 degree sector reflector (~10dBi) attached to the omni, I have seen almost a mile with better laptops. |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
Problem solved! After a lot of kicking, screaming and dragging my feet I finally agreed to my partners suggestion to replace the SR2 card with a prisim card. He felt that the Prisim card had better receive. Yesterday I climbed the tower, swapped out the card and now it works like a charm. We made no other changes other than to swap the card and then of course tell Mikrotik to use the new card. I guess now we'll order another Prisim card for our other hot spot which should increase it's range dramatically. |
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jdmarti1
Jack
join:2004-06-15
Oilton, OK
| I don't thinkt he Prism has a better Rx sensitivity, look at the specs. I would bet that the problem lies in the fact you had the SR2 using default power. I had the same troubles with my laptop when we first built our AP, I was playing before I put customers on it, and found if I turned the SR2 power way down, I could connect no problems. Try that on you next one - significantly reduce the power to the SR2 (you will have to play to find the sweet spot). Think about how much power you were sending that poor D-Link card!!!
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»magicwisp.com |
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thewildthang
join:2005-12-21
Winfield, AL
| reply to thewildthang
I don't have a clue why it works now and wouldn't with the SR2, however, we did turn the SR2 down as low as 50mw. I've got another hotspot that serves its purpose but has limited range which is also using an SR2, I'll play with the power output on it a little before changing it out with a Prisim card, will let you know how that turns out. |
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