What Effect does Terrain or Water have on Radio Propagation?
WLAN signal paths on 2.4 and 5.8 GHz must be line-of-sight. There must not be any hills, mountains, large buildings or obstructions for the signal to pass through. Visual line-of-sight is sometimes not enough. The University of Kansas Wireless Network Visualization Project can help you visualize coverage areas. The radio path should also allow for Fresnel-zone clearance. (See Reference 1) A few trees (0.3 – 0.5 dB/meter) are not usually a problem, however a forest will block the signal (300 dB/km). You can check topographic maps of your area at Topo.Com or Topozone.Com. Also, there a few cool 3D tools such as Keyhole’s Earthviewer. You can find your exact latitude & longitude for any address at Geocode. Find distance and direction between two points at Indo. Find the elevation at any lat & long from Widders. Path profiles may be created using TopoUSA or Terrain Navigator. There are also several companies who market propagation modeling software. We recommend Wireless Valley, EDX Signal
