Gain vs relative coverage distance equation anyone?

[Sparent]

Hey all,

Is there an equation that allows me to look at the Gain figure of an antenna and determine a RELATIVE coverage distance? I assume that we have a free line of site (L.O.S.) and that the weather is clear, hence the word RELATIVE. e.g.: 15 dBi = 9 miles/15KM


Any help will be justly appreciated

Simon

 

[xp]

Simon,
Have a look at the cisco wireless range calculator (download from cisco.com). Allows you to try different antenna gains and shows ranges with 10dB fade margins.

Brian

 

[Sparent]

Thank you sir, I will dload it and have a good look at it.

Simon

 

[lui3]

generally speaking (in a theoretical since) if you double the gain, ie 6db increase you will double the coverage distance in clear space. the problem comes in calculating all the other factors besides the gain of the antenna. power gain, cable loss, interference etc. the cisco bridge calculator is a nice place to start.

also keep in mind that generally speaking the higher the gain of the antenna the narrower the horizantal beam width.

ie the 12 dbi cisco omnidirectional antenna has a 7.5 deg horizantal beam width. its range is in miles but with the narrow beamwidth ists really only useful for point-to-multipoint bridging.

there is also the 21 dbi directional parobolic dish with a range of up to 20+ miles but that too has a very narrow h and vertical beamwidth. more gain is not always better. depends on the design. good luck

Lui3
CCNP,CCDA,A+/Net+
Cisco Wireless Specialization