What Use Is An F-call?

What use is an F-call? You've come across the term dB, or Decibel. Likely you've heard of dBi as well. These terms are all related to Decibels, but mean completely different things. A decibel, named after Alexander Graham Bell, is a RELATIVE measure of two different power levels, that is, one power level compared to another power level. 3dB is about twice as much power, 6db is about four times as much, and 10dB is exactly 10 times as much power. This means that you can say that a feedline has 6dB loss, that is, you need to put 20 Watt in at one end to get 5 Watt out at the other. In short, a dB is a ratio between two levels of power, in the feedline case, the power in vs. the power out the other end. In antenna land, you'll have heard dBi as the measure of the amazingness of an antenna. A dBi is a measure of gain of an antenna when compared to an ISOTROPIC source. This is a theoretical reference, that cannot actually exist in nature, but at least it's always the same, which allows you to compare two antenn