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Thorn · 01-04-2003

"Generally speaking" a 5 dB and a 15dB are good antennae for the two stated purposes.

You can predict how well a signal will be received if you know the 1) transmitted power level, 2) the receiver sensitivity, and 3) the gain of both transmitting and receiving antennae. This assumes that there is open space between both antennae. However, there are so many things that can influence the signal, it is literally impossible to predict the what the range of an anternna will be under all circumstances. Especially since you don't know the transmitted power and the gain of the transmitting antenna.

Remember too, that 2.4GHz RF gets blocked and reduced by any number of things in the environment; brick, sheetrock, steel, and trees (especially pine trees) are a few. Those things will have as much, if not more, effect on your results as the antenna.

It also depends on exactly what you are doing. When I'm in the field, I keep four (4) antennae with me. Depending on the job and even the specific task, I may be using a 3dB omni, a 4.5 dB omni, a 8dB yagi, or a 19dB panel.

Finally, don't get to hung up on the gain numbers as an absolute, because gain expressed as a deciBel is by definition, relative to a known power source.

Thanks, I'm glad you found the diagrams useful.

01-04-2003	#3 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,140	"Generally speaking" a 5 dB and a 15dB are good antennae for the two stated purposes. You can predict how well a signal will be received if you know the 1) transmitted power level, 2) the receiver sensitivity, and 3) the gain of both transmitting and receiving antennae. This assumes that there is open space between both antennae. However, there are so many things that can influence the signal, it is literally impossible to predict the what the range of an anternna will be under all circumstances. Especially since you don't know the transmitted power and the gain of the transmitting antenna. Remember too, that 2.4GHz RF gets blocked and reduced by any number of things in the environment; brick, sheetrock, steel, and trees (especially pine trees) are a few. Those things will have as much, if not more, effect on your results as the antenna. It also depends on exactly what you are doing. When I'm in the field, I keep four (4) antennae with me. Depending on the job and even the specific task, I may be using a 3dB omni, a 4.5 dB omni, a 8dB yagi, or a 19dB panel. Finally, don't get to hung up on the gain numbers as an absolute, because gain expressed as a deciBel is by definition, relative to a known power source. Thanks, I'm glad you found the diagrams useful. __________________ Thorn "I'm The Doctor. I'm a Time Lord. I am from the planet Gallifrey in the constellation Kasterborous. I'm 903 years old and I am the man who is going to save your lives and all 6 billion people on the planet below... You got a problem with that?"