Hey guys, I'm connecting a remote mountaintop (1,900m) weather station equipped with a 22Mb PCI card (Planet WL-8305) to an AP (22Mb Planet WAP-1965) in my office which is in direct line of sight.
Does anybody have any recommendations re antenna selection?
The data from the station is to be accessable online via the office network which is connected to the 'net via JetStart 128 so speed isn't a major issue.
Hi Etienne, thanks for the reply! I guess I should have eloaborated a little. I really wondered if anybody had preferences re suppliers, etc. Our choice has always been yagi or parabolic, and to that end we acquired two satellite TV antennas, but yagis are less effected by wind (and man it gets windy up on the mountain!). The commercial models offered so far have all been pretty expensive ("discounted" to $250+ each) and outside out meagre not-for-profit-outfit budget. If you or anybody can recommend a good supplier of yagis (or whatever) feel free to do so! :-) Or links to good DIY antenna sites would be helpful too.
Thanks again guys. I took a look at Borg. They don't appear to have much in the way of yagis, our favored option right now (due to low wind-loading), and the parabolic grids, although good, are not much cheaper than the high-end yagis we've been offered.
We might take a stab at modding the sat-tv antennas Uniden donated...anybody have the links for such mods?
The weather station is on Benmore Peak, which is between Twizel and Omarama. It's page is:
One antenna you may like to have a look at is the Borg Twinfire. These antennas can be used either on their own or as a feeder for a parabolic grid. When compared to a 15dbi grid antenna they were only about 2dbi down in signal and for something that is less than 1/4 the size we think they work prety well.
We will have a range of Yagi's avalible shortly.
As an alternative you could try a pair of Ingot antennas however over that distance you would need to make sure there was no movement on any of the poles as the beamwidth is prety tight on them.
A couple of grid type antennas would also work well. the 19's should give you an exceptional signal at that range.
One antenna you may like to have a look at is the Borg Twinfire. These antennas can be used either on their own or as a feeder for a parabolic grid. When compared to a 15dbi grid antenna they were only about 2dbi down in signal and for something that is less than 1/4 the size we think they work prety well.
What kind of signal strength could we expect from a pair of those over that distance on their own? Snow is a factor down here, and the town's Telecom exchange (complete with microwave link) is -- naturally -- slapbang in line-of-sight (around 300m from the Omarama end).
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We will have a range of Yagi's avalible shortly.
Any idea on pricing yet?
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As an alternative you could try a pair of Ingot antennas however over that distance you would need to make sure there was no movement on any of the poles as the beamwidth is prety tight on them.
Heh. I'll embed the mountaintop one in a couple hundred tons of cement. That might do the trick. However not so long ago I went boot skiing up there. This basically entails standing still and allowing the wind to push you along on the snow, sans skis. You let yourself fall over if, a) you think you are going too fast or, you are approaching the side of the mountain (1,900 meters straight down) or, c) all of the above. 'Tis windy up there sometimes!
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A couple of grid type antennas would also work well. the 19's should give you an exceptional signal at that range.
Regards
Andrew
They look excellent, but are a little outside our budget right now.
I would not like to guess the signal strength for that, Bigted gave me some netstumbler logs a while back when he was going around auckland testing the coverage of his waveguide. he used the 15dbi parabolic grid as a referance antenna and was getting some prety spectacular readings from some distant places. another client also has oen mounted in his opffice down in wellington shooting across the harbour to a 24dbi at his house. this I beleive is giving him something like a -60 but willl try and confirm this. I think he was getting a 4mb stable connection. range was over a distance of 1.8km. The critical factor woud be to ensure that both antennas are perfectly aligned and clear of anything that my create a fresnel zone.
I can no guarentee that the Telecom Exchange will not cause problems but i think you will find that they are using frequenceies way outside the range of the 2.4ghz spectrum. Dont quote me on this but i seem to remember 3ghz, 8ghz and 10ghz being used.
Pricing for the Yagi's has not been set. We are hoping to get them down to about the $150 to $160 mark but are still working on this one. we have a Borg Yagi planned for release later in the year but the estimation will be in the last quarter. good news is that the target price for these is set at about $115.00.
Snow may also be a problem, Water can interfere with the microwave transmissions. but again these things depend on how creative you want to get. One way is to up the power to cater for the loss. the other way os to make a snow shroud to ensure that no snow lands on your antenna transmission face.
How hard is it to get up there to test gear/antennas?
I have unobstructed line-of-sight, and whatever antenna we put in place will definitely be protected from the elements as much as is practically possible. The population is small around here, and not too many cellphone repeaters, garage door openers, etc! The only water the signal will be passing over is the Ahuriri river, as the lakes are all off in different directions. It's also spectacularly dry in the Nth Otago/MacKenzie region (another good reason to site an observatory here!), so all-in-all it's a great place to play the How Far Can I Go WiFi game
Access to the site is generally good, but can be restricted at any time by snow: I've had two white Christmases on Benmore Peak! I need to get this sorted before the winter returns (meaning around April here). One issue is that it's a looong drive to the top, and not one I like to repeat unnecessarily. I can't wait 'til the permanent accommodation is completed properly...
Anyhoo, so long as I can get the data from the station onto the 'net, I'll be happy. Since we only have a 128kbps Jetstream Starter link, it doesn't really matter if we can't sustain 22mb from the summit!
Need Advice re a 15km WiFi Link. 
you are approaching the side of the mountain (1,900 meters straight down) or, c) all of the above. 'Tis windy up there sometimes! 
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