rfrobenius's blog

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".

Self-study Guide: RF Small-Signal Amplifiers (LNA)

Back in the mid-1990's, Les Besser and I wrote a series of articles on RF amplifier design for Applied Microwaves and Wireless magazine (unfortunately this magazine is no longer in circulation). Since that time, Les Besser and Rowan Gilmore have written a two-volume textbook on RF circuit design that covers this topic as well as a great deal of background knowledge on working with RF circuits.

Marconi Radio Near San Francisco

One of Marconi's original radio sites lies in the Point Reyes National Seashore about 35 miles across the Golden Gate Bridge to the north of the 2016 IMS show. This site served both trans-Pacific and ship to shore communications companies. Unlike their East Coast counterparts, these sites are located within National Park lands and were therefore not torn town.

The Mother of All Demos

In the days leading up to this year's IEEE IMS show in San Francisco, I'll be presenting some fun trivia facts about the San Francisco/Silicon Valley region that may be of interest to our visitors coming to the show. In each case, i'll try to keep some sort of wireless relevance to the post.

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.

Evolving Satellite Market

The successful landings of Space-X's first stage rockets (and Blue Origin's success as well) signals a major breakthrough in the future reduction of the cost of space access. It seems to reason that this will result in a dramatic increase in the entrepreneurial interest in using satellite-based infrastructure to provide new services to a global audience. For example, companies like Google could deploy wireless internet access using small "cube" satellites that cost much less to build and launch than current systems.

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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