The iB003N-PA has a range up to 300m because it uses the RFAXIS X2401C 2.4GHz amplifier to increase the range.
When you use the manufacturer app to change the power output by a beacon, you are changing the power output by the Nordic nRF51 System on a Chip (SoC) that is usually fed to the antenna. In the case of the iB003N-PA, the RFAXIS X2401C instead receives the signal, amplifies it and sends it to the antenna. The resultant change in output is:
20dBm is the maximum allowable output for class 1 Bluetooth. There’s no difference whether you set to 0dBm or 4dBm, the output will be 20dBm. Even at a low power setting, -10dbm, the amplified output is 10dBm which is relatively high compared to the nominal 0dBm for most beacons. That’s just over 3x the power (3dBm change is a doubling of power) of a normal beacon. You can see that this beacon is primarily designed for long distance and there’s no need to change the SoC power from the default 0dBm = 20dBm.
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