How much improvement in range if I replace the 2dBi antenna with a 3.1 dBi antenna on the ground module only of my 915 MHz radio?
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How much improvement in range if I replace the 2dBi antenna with a 3.1 dBi antenna on the ground module only of my 915 MHz radio?
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Are there any other higher gain antennas available that would worth looking at?
I always try to figure things with ERP instead of EIRP.
Here's a quote from another post I made...
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I got two of these 3.5dBi antennas...
http://www.ebay.com/itm/290362347165?ssPageName=STRK:MEWNX:IT&_...
100mw * 2 dBi = 158 mw EIRP, 97 mw ERP = -3%
100mw * 3.5 dBi = 224 mw EIRP, 137 mw ERP = +37%
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I can't vouch for the online calculator I used, but ERP is what actually matters as far as what you receive. The stock 2 dBi antennas give you about your rated power. 3.5 dBi antennas will give you quite a boost. They're also quite a bit larger and you can't always trust that the specs are true.
I wish I had both to compare actual range, but I couldn't wait for the "kit" to be in stock so I ordered air and ground modules separately from 3DR and bought my own antennas.
For comparison purposes, I'll assume no antenna cable loss and 100mW transmit power.
In terms of transmit (and this will give a general idea of receive also):
2dBi antenna is effectively 158mW EIRP
3.1dBi antenna is effectively 204mW EIRP
What does this mean? I've run some calculations. The theoretical range for both 2dBi antennas is about 2783 meters. In reality, it will be much less (because of loss in the connectors, orientation, and low signal quality.) But we can compare between the other values:
2 dBi to 2 dBi will be 2783m