Or, also known as “linear units in a logarithmic world”.
Among the cheap handheld radio community, especially after the release of the Baofeng BF-F8HP, there seems to be this huge obsession with RF transmit power. Yes, the BF-F8HP is rated at 8 Watts on its maximum setting, but what do you really get for that doubling of output power over the regular 4 Watts of the UV-5R and similar HT’s? Double the range? Not even close.
Doubling the power adds 3 dB. As a rule of thumb, you can consider a 6 dB increase in transmitter output power roughly equivalent to double the communications range. That is four times the power.
So, what do you get from doubling the output power? You get to move the S-meter on the receiving end of the link up by half an S-unit.
UV-5R = 4W (36 dBm) output.
BF-F8HP =8W (39 dBm) output.
1 Collins S-unit = 6 dB
Moving from 4 Watts to 8 Watts = half an S-unit.
Want to really move the needle at the receiving end of the link? Let us consider this example…
Let us assume you have no gain in your antenna. If your transmit power is 1W (30 dBm), and your received signal level is an S1, the following illustrates how much power you would need to use in order to step up in one S-unit (6 dB) increments.