I've done some updates to a couple of calculators on the site. The Animated Reflectometer HTML5 version had a bug where the animation would be drawn with the wrong sign for values entered into the load impedance (ZL) field. The displayed numerical results were correct, but the animation would demonstrate an open circuit condition if you entered zero impedance for the load, instead of displaying a shorted condition. This has been fixed now.

I was recently updating one of the online workbooks for the RF Technology Certification program and decided to try and re-write one of the calculators using Python. The topic is teaching how to convert from dBm values to milliwatts without using a calculator, so the calculator does not just calculate the conversion, rather it tries to demonstrate the process of approximation in your head. In the end, I decided to keep the original Javascript calculator with some updates rather than replacing it with the Python version.

I created a quick Python function to calculate the component values for an impedance match between two real (resistive) terminations using the technique taught in the Introduction to Impedance Matching course. Here is what the code ends up looking like, and it shows how useful Python can be for working as a "quick programmable calculator." In the old days, I might have been tempted to program my old HP48 calculator to crank out the same values. It only took a few minutes to put the code together, which is the beauty of working with Python.

I've made substantial progress in developing the JavaScript version of the Smith Chart matching applet. The interface components that allow for changing frequencies and viewing component values have basic functionality at this point. A basic interface for setting the chart impedance is all that is needed and then all of the basic pieces will be in place. I should be able to make it available users very soon - although the appearance will start out a bit "unrefined".

Another application of using Python to demonstrate RF concepts comes in the form of a calculator to plot L-C series reactance. This plot shows two useful concepts: resonance and the effect of parasitic capacitance or inductance. For a capacitor, the magnitude of the series reactance decreases with increasing frequency, while the opposite is true for an inductor. For a capacitor with parasitic inductance, there will come a point where the two reactances are equal in magnitude and cancel each other out. This point is the resonant frequency of the combined circuit.