rfrobenius's blog

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".

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.

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