How to calculate impedance in simple transistor oscillators/amplifiers?

Impedance issues were always struggling me brom designing my own homebrew RF suff.
Is there any good source that explains in simple steps how to calculate the impedance of simple transistorized rf circuits in different transistors configuration? (emitter follower etc).
I would like something that is not so theoretical, practical examples yould be great

Use s parameters

So that seems to be an issue for experienced rf engineers...

Hi neazoi,
The other easy way (but unfortunatly , expensive way in term of money and time ) is to build a prototype of your oscillator and then get the measurement with a Network Vector Analyser.
As a not so much experienced hobbyist, I have fonud for me that this is the only feasible way to get good results.
Theory is very good, but at the condition to be founded on solid knowledge of the subject. And I am not.

Giovanni

For smal signal driven conditions, input/ouput impedances are measured with s-parameters with VNA due to difficulties of measuring of z and y parameters at higher frequencies.
For large signal driven conditions, load pull tuning is more convenient but it's pretty expensive.X-parameters measurement is also an alternative to characterize a sytem ( amplifier,mixer etc.) by using
X-VNA measurment equipments.But it's so expensive too...
Every beauty has a price...

or make something that it's not so expensive VNA / Antenna Analyzer
anyway this is far beyond a radioamateurs skills. I wonder, all these great articles that have been presented in arrl over the years, are they all analyzed for correct impedance matching between stages...?