Quote:
|
Originally Posted by Novilio
One issue that I didn't see brought up earlier in this thread is wind loading. If your antennas are out in the open (rather than tucked under the eaves of a building) you have to take wind loading into account. A yagi is good from that standpoint because it's basically a long rod with some teeth on it. Its wind profile is quite low, and once you point it, it's likely to stay pointed. Large parabolics can have a very high wind profile unless they're skeletal, like the ones you see at FAB. (They look a little like warped barbecue grills.)
|
Yeah, I know I need to consider wind loading as well. Our redundant ISP connection is actually a parabolic (not sure of the gain, off the top of my head) dish on a high mast on our office roof, and it hasn't moved in the 18 months I've been here. Similarly, we've got a 2.7m VSAT dish that's our primary link to our ISP; and believe me I know how much wind that thing catches!
Quote:
|
I've BSed with guys here who have tried to use old satellite dishes for very high gain wi-fi point-to-point, and wind shoving them off target was a constant issue. It's not for nothing that in satellite service they're typically mounted on a piece of 3" or 4" pipe sunk in concrete.
|
Well FWIW, when I had a 2.7-meter dish at the roof our building, the thing was held down with around 360kg (what, 800lb?) of concrete on EACH of it's four feet. So, yeah, construction is important! And yeah, the central mast was at least 4" pipe. I'll take some photos if anyone is interested, wireless doesn't have to mean 802.11x standards!
Quote:
|
One final note: This is a big, complex project, especially for a beginner. Research it thoroughly and do a test connection between your base and one of those outlying nodes before committing a bundle of money to hardware. Especially on the antenna side, like Thorn said, do the math. Calculate your link budget before you buy anything, or you will be sorry.
|
Yeah, you're right; it is. At the moment I'm trying to calculate cable runs & associated losses, from there I'll do the sums to see how my signal strength is going to pan out over the link.
Once I'm satisfied that I'm gonna have what it takes for the network to work, I'll source the two antennae and use two AP/Bridges I've got lying around to test. Not that it's my money, but...