[SOLVED] Omni-directional antenna or not?

[pijesiv118]

currently have 1 ALFA AWUS036ACH adapter that comes with stock 2x 5Dbi omni-directional antennas. will get a significant range improvement if upgrading the antennas to 9Dbi ones?
plan buy this one https://www.amazon.com/Gadgets-World-FBA_ALFA-ARSN19M-OMNI-Directional-High-Gain/dp/B0039ORBLK if the extra expense worth it

 

[bill001g]

Not really. First it is likely illegal because you will exceed the legal effective transmit power. Next the antenna are generally matched to the radio power. So you get 24db of radio power and 5-6db of antenna to get the legal 30db of power. The problem with a larger antenna is that unlike a microwave amplifier they increase the noise as well as the signal. It many times will overload the input on the amplifier. The best would be a microwave amplifier that put out say 29db with a 1db antenna. Problem is it is very expensive to make the amplifiers and the cost goes up as you increase the power. What they found is the best price/performance is 250mw radios with 6db of antenna which will give 1watt or 30db of power output.

In general you might get stronger signal levels with larger antenna but you also have increased the noise you are receiving.

You have to be a little careful of ALFA. They have gotten better but they tend to "lie" about the power output and coverage. They are limited like every other manufacture by the government limits. They can pretend they are better but most device put out the legal maximum. This ignores the fact that they almost encourage people to run illegal antenna.