Unterschiede

Hier werden die Unterschiede zwischen zwei Versionen angezeigt.

--- project:hgg:shf:lowpass [2012-01-05 10:33] – 84.56.156.215
+++ project:hgg:shf:lowpass [2012-01-05 10:41] (aktuell) – 84.56.156.215
@@ Zeile 35: / Zeile 35: @@
 Since we did not have a device for measuring an Inductor but very just inductors (1%) we decided to use one of the inductors. We set our Cutoff Frequency and calculated the needed values. Calculations were performed for one of the base filters (LC). Thus we took two inductivities (L) from the stack and one Capacitor with double the size as for one filter (the picture above says 2C).
+Forget formulas for more complicated filters but use simulation tools instead! There is a very old DOS based software "PUFF" which shows the frequency and phase response of a given filter, consisting of lumped constant components as L, C, R and (!) transmission lines (traces on the pcb).
 ====== A few words on HF ======
 As we have found out while experimenting, in HF almost everything becomes a lowpass, but not in the way we wanted it to be. Things on how to make the PCBs should be added here.
+If the wavelength is less than approx. 10 to 100x the size of your components or wires in the circuitry, you will have lots of parasitic effects due to line inductance or stray capacitance which alter network behaviour. Example: At frequencies about 1 GHz, (wavelength 30 cm) you cannot use wires etc. longer than some millimeters without considering its parasitic effects.