Digital HF Antenna Analyser

This instrument measures complex impedance over the 1. 6 - 33 MHz HF spectrum. It also calculates and displays the VSWR of the impedance referenced to 50 ohms. The most common application of the meter is as an antenna analyser. The design was published in `Break-In`, New Zealand`s amateur radio magazine in Jan/Feb 2006, and is republished here with
Digital HF Antenna Analyser - schematic

the permission of the editor. Note: `Break-In` is a term used in amateur radio to describe a system which allows another person`s signal to be heard in the brief intervals between transmitted Morse Code symbols. Why is it that having reached the top of the mountain and just begun to enjoy the rewards of the climb, you realise that there`s another peak just that little bit higher to be seen in the distance Such was the case a month or so after I completed an analog antenna analyser. The analog meter did everything demanded of it, but there were times when a little more information would have been useful. I`d seen the next mountain top. (The analog meter is described on another page on this website) I discovered, for example, that there are times when full information about the complex impedance being measured can be useful. An impedance is made up of two components; the real or resistive part, R`, and the reactive part, X`. The reactive component may be capacitive or inductive. Complex impedance can be displayed in two ways; Either as a magnitude plus a phase angle (i. e. A magnitude of "A" ohms at a phase angle of "B" degrees) or as a series combination of real and reactive components (i. e. C +/- jD ohms) where j` indicates the value of "D" is reactive. If "D" is positive, the impedance is inductive. If negative, the impedance is capacitive. While it is possible to measure and display these components of a complex...

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