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So what is it you would say determines wither or not my signal will be
received on the other end? I mean with just a regular soho wifi access point in open space you can only communicate within a couple hundred feet (That's open space). If gain/wattage isn't so important when we're talking distance.. what is? Line of site? Are you saying that that I can shoot my 30mw signal from my soho access point couple of miles? I've spoken with a guy who has set up a number of reliable point-to-point links in the Sacramento valley, using standard unamplified off-the-shelf SOHO-type access points and/or PCI cards or USB dongles. He said he achieves reliable performance, with a good margin of signal strength to handle rain fade, etc., with no amplifiers, over distances of as much as 5 miles. The key to doing this are a clear line of sight, an antenna with high directional gain at each end of the link, and careful aiming. Getting the radio right up at the antenna (rather than at the end of a length of coax) is also beneficial. The carefully-aimed highly-directional antennas give you several advantages, over a standard SOHO omni antennas. The directionality increases the effective radiated power of the transmitter (50 milliwatts through a 20 dBi antenna is equivalent to 5 watts isotropic), it increases the receiver's effective sensitivity by the same degree, and it makes the receiver _less_ sensitive to interference arriving from other angles (e.g. competing transmitters). Also, with proper choice of antenna, you can select the signal's polarization angle. Since most home and business access points seem to use vertically-oriented antennas (and thus a vertically polarized signal) you can reduce interference problems by using point-to- point antennas which are horizontally polarized. The guy I spoke with was not complementary about the idea of trying to "blast" signals through by using high-power transmitters or amplifiers, and blanketing a large area with the signal. You can buy wire-dish parabolic antennas for the 2.4-gig ISM radio band quite easily. I think I've seen 'em advertised as having 15 to 19 dBi of gain. One of these at each end of the link would be a good place to start. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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