Javascript

Posts related to the use of Javascript in creating utilities for this site.

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.

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).

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.

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