Technical Notes

This article describes principles involved in design of the type ST940B NVIS antenna system and provides useful information on HF communications techniques.

The SMITH chart is a graphical calculator that allows the relatively complicated mathematical calculations, which use complex algebra and numbers, to be replaced with geometrical constructs, and it allows us to see at a glance what the effects of altering the transmission line (feed) geometry will be. If used regularly, it gives the practitioner a really good feel for the behavior of transmission lines and the wide range of impedance that a transmitter may see for situations of moderately high mismatch (VSWR).

This article discusses the basic unit of measurement used in radio signals: the decibel or dB. It is named after Alexander Graham Bell - that is why the “B” is capitalized. There are several variations of the dB used in radio. This paper contains some definitions and explanations of dBs, plus other related terms and concepts that you might find useful in implementing your wireless systems.