Programming

These entries discuss programming as it relates to RF and wireless in general or utilities on this site specifically.

Free Access without Logins

News update! We are no longer requiring logins to access the free Smith Chart and Reflectometer web apps on RFMentor.com!

We are working on updating our login system to work more smoothly for our RF Mentor Academy users. As part of this transition, we are no longer requiring users to have an account to access the web apps on RFMentor.com. You can still log in if you wish to comment, but it is no longer necessary to simply use the apps.

Look for more news regarding the Smith Chart app in the near future!

 

Calculators Maintenance Update

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.

Here Come the Calculators!

I've been experimenting with JavaScript a bit lately and came up with a bit of code to make creating calculators for RF Mentor users quite a bit easier. Based on the fact that most of the online calculators share some common functionality as far as the website is concerned, I've created some base "formula" and "variable" objects to handle the creation of the input form and display tasks. As a result, creating a new calculator is a much simpler matter of defining the variables and writing a function for the calculation of the output value.

dBm to Milliwatts Conversion Tutorial with Python

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.

Transmission Line Elements on Smith Chart Web App

I've successfully added transmission line elements to the Smith Chart matching web app here on RFMentor.com. These include series, shorted shunt section, and open shunt section. There's a trick you can use to have these transmission line elements use an arbitrary characteristic impedance. The elements adopt the same characteristic impedance as the chart normalization impedance (default is 50 Ohms).

Analytical Impedance Match with Python

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.

Smith Chart Matching HTML 5 Version

An early version of the Smith Chart web app is now available to try out. There are a couple of issues that I will be working on initially, such as the frequency entry dialog box appears to be transparent for some reason. I'll also be working on the layout to try and make the various parts of the app fit better on the page. At the moment, the app is only optimized for mouse input and does not respond to touch-based dragging events (to move elements around on the chart).

Smith Chart Matching Web App

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".

Applets are Dead(?) Long Live JavaScript

Now that browsers are dropping support for the Java plug-in, it seems that the days of applets are coming to an end. Although Java applets never dominated the mainstream web experience as much as more popular Flash-based content, they did find a niche in scientific and engineering applications - which is one of the few areas where they will likely be missed.

LC Resonance Plotter

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.

Pages

Subscribe to RSS - Programming