The phenomenon known as RF interference — RFI to its many friends and acquaintances — involves interference caused by signals propagated wirelessly as radio waves. Most people don’t know (or care) about RFI until their garage door opener won’t work.
Rings, beads, cores ... find out exactly what ferrite is and what makes it ideal for a variety of uses in electronics. First created in 1930, they have since become important materials in the electronics and RF world.
Listening to shortwave radio is very interesting, and filled with the voices and music of far-off lands. Digging a bit deeper, there is another world of shortwave radio that does not use conventional sounds. It is the realm of data transmissions.
Every signal begins with an oscillator — In ham radio, the oscillator is a key element in generating signals, mixing them together, and extracting the information from them. Let's see how to make an audio oscillator, plus learn about common RF types.
Previously, we learned what makes an oscillator do what it does, and tried a simple low frequency example. Now, it's time to move up — in frequency — to the oscillators which make the signals that drive the ham's wireless world.
The Smith Chart is one of the most useful tools in radio communications, but it is often misunderstood. After reading this introduction to the basics, you will have a better understanding of impedance matching and VSWR — common parameters in a radio station.