At a well attended August meeting, Giles G0NXA introduced us to the basic principles of antenna matching and the Smith Chart.
Giles explained that we need to match the antenna to the feeder for three main reasons:
- to maximise power transfer,
- to minimise the SWR (standing wave ratio) on the feeder so as to avoid power fold-back or shut down by (solid-state) PA protection circuitry,
- to minimise power loss in the feeder (which can occur with a high SWR).
He then went on to talk about complex impedances, how they can be described and measured, and concluded with a description of the Smith Chart as a method of solving matching problems by graphical means.
Another very good club meeting, with lots of interesting and useful information being presented. Many thanks go to Giles G0NXA for giving us the talk and for presenting the information in a readily understandable manner with many tangential stories to illustrate the points he was making.
Many thanks also to Peter G3YJE for yet again manning the tea/coffee bar – volunteers for future months would be most welcome.
Derek G3NKS