Bounce off a condo tower

• posted

I'm looking to connect my WAP to a client less than 1 km away. We would have perfect line of sight except for the senior's complex directly in between. I understand that this is a complete no-go. However, approximately 1/2 way between and off to the side there is a cluster of large condos (mostly concrete & glass on the outside) that I think I can bounce a signal off of. My questions are:

1. Point A (WAP) is on the 2nd floor, point B (client) is on the 4th, but in order to clear some trees and other houses, we'd have to aim for about the 10-15th floors of the condo. Principles of reflection tell me my signal will end up several hundred feet above my target. Am I going to end up with enough "splatter" to make it back down?
2. What sort of additional hardware will I have to work with for a reasonable test? Can I use a cantenna-type deal on both ends and expect a decent result?
3. If I put a directional antenna on the WAP, will I still be able to access it locally (client within the same room) even though the antenna is pointing in the other direction?
4. How much better will my result be if I befriend someone in the condo and get him to put in an omni?

Sorry if these issues have been beaten to death already.

TIA Jeremy.

--There are no stupid questions, but there are a lot of inquisitive idiots.

• posted

Won't work. Do the math. Let's say your 24dBi dish antenna has a

-3dB beamwidth of 8 degrees. That's half your power going into 8 degrees. At 500 meters away, your reflector would need to be: diameter = 2 * tan(4) * 500 = 70 meters That's a circular area of: Pi * (35 meters)^2 = 3900 sq meters to capture only half the power from the antenna. If you prepare a realistic midpoint reflector of perhaps 1 meter square (ignoring reflection angle), your reflector would capture only 1/3900th of the signal resulting in a loss of: loss = 10*log(1/3900) = -36dB Reflection efficiency is at best 50% (-3dB). So, our total loss coming off the reflector is: 3 + 36 + 3 = -42dB loss Now, that's the loss in *addition* to the path loss between endpoints. It won't work simply because you can't build an antenna narrow enough to concentrate the signal on a reflector, which you can't build large enough to capture all the signal.

No. Search the net for calculations for "periscope antennas".