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Hi Bryan
I'd try and model this for you but the s/w I use is broken at the moment. You can calculate path loss over an LOS path fairly easily. If you start with the RF output in dBm, add antenna gains, subtract the path and cable losses you'll get a close result. This can then be applied against the receiver sensitivity (I use to use -87dBm for 802.11 links) If you want to model in the existence of a reflector or (say) back to back yagi you do it is two paths using the received power at the reflecting device as the source power for the next minus about 3dB. The results tend to be less than encouraging in most places but it depends on the application. One study I did (for example) was to get a 410MHz signal into a railway cutting on the edge of a mountain. (ie no source of reflection from the other side) The 25W TX was about 2km away and we modeled two back to back 13dBi antennas. With -82dBm as the lowest specd RX signal we only got about 300m range from the reflecting array. Freds suggestion of using a billboard is however a good one and simple to experiment with. I also agree that the powerline wont be much help. Pls tell us how it works out! Cheers Bob VK2YQA Bryan Martin wrote: I am attempting to setup a 802.11b bridge between my location (siteA) down the powerlines but off to the right NLOS (siteB) roughly 1 mile away. |
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