HF final stage matching to antenna

Has anyone of you seen a final stage to antenna matching configuration as shown below. If yes, can you explain the logic behind it. i.e. how it works..

The coil and capacitor are simply tuned to the frequency in use, and the input and output are tapped on the coil to give correct impedance matching.

ok, i got the first point, but how about the second point i.e. impedance matching. How are the calculations done for this particular configuration. Also how do we find the output impedance of the final Transistor.

You will find a lot of good info on this subject in amateur radio publications - ARRL Handbook and some others focused on RF design. Sorry I don't have anything I can cut/paste from - all of my references are plain old books.

Vaibhav Birit said:

ok, i got the first point, but how about the second point i.e. impedance matching. How are the calculations done for this particular configuration. Also how do we find the output impedance of the final Transistor.

Click to expand...

The data sheets for most r.f. power transistors will show the transistor's output impedance across the range of frequencies for which they are designed. They will be plotted on a special graph called a Smith chart. (Search for tutorials in Google.)

A good book which deals with matching is RF Circuit Design -- by Christopher Bowick.