Some software has been added to this page. It evaluates the transmission for a coaxial line filled with a material.
The material in this case is water but the program can be changed to any other material by changing the permittivity. Try the EXCEL program Calc_w
If the liquid ETHANOL replaces water then we change a2 to 26, a4 to 4.5 and d2 to 0.016
If we have just AIR in the cell the we change a2 to 1, a4 to 0.000001 and d2 to 0.000001 — so we then have a dielectric without loss and the permittivity stays at a constant value of 1 for any frequency.
The simplest thing to change is the sample thickness — change value from 2 to 4 and notice the trace being “sweezed” . Also one can alter the scaling factor from 6 to 12 and so see a frequency scan up to 12 GHz.
A simple experiment on Lecher Lines is described. I found this to be a useful experiment when at University in the 1950/60’s for making the transition from LOW FREQUENCY electronics to radio frequency (rf) and microwave circuits. Example of transistor circuit, components easy to measure:
This is completely different from an rf/microwave circuit where an example is given for a Generator connected to a resistor (load) by some coaxial cable.
The microwave circuit is given below
I guess the process of growing old makes one very aware of one’s “sell-by” date. Teaching students, looking after grandchildren and, above all, trying to maintain reasonable health does push this date back a little. Each year I will say “just give me another year!”.
A few more thoughts on Microwaves .