Foundations Of Amateur Radio

Foundations of Amateur Radio If you've ever been on the hunt for an antenna, and let's face it, in amateur radio that's pretty likely, you'll get information about the gain of an antenna. Often someone will tell you that this one has 12 dB gain, versus that one which only has 9 dB. As an aside, I've seen a few videos where people are comparing sound levels and mention that without the fan, there is only 3 dB less noise. What they don't realise is that 3 dB means HALF the noise. The same is true with an antenna. That 9 dB antenna has half the gain of a 12 dB antenna. In the past I've talked about gain. It's always in comparison to something else. If I say "that antenna has 12 dB gain", I'm actually saying: "that antenna has 12 dB gain when compared with an isotropic source". To jog your memory, an isotropic source is a theoretical source of electromagnetic radiation. It cannot actually exist. It radiates uniformly in all directions. Now when we talk about gain, we're saying that our new funky antenna radi