A Low Cost RF Impedance Analyzer
by George R. Steber
Measuring the impedance of an antenna, a component, or a circuit such as a matching network, can often help us optimize our equipment and improve our understanding of its operation. Commercial network analyzers, RF impedance meters, or antenna analyzers can do the job, but are out of the realm for many amateurs, especially since the equipment is expensive and would be sitting idly on the shelf most of the time. If we only need a few measurements, an old technique — the three voltmeter method — that uses a signal generator (or a QRP rig) and the ubiquitous digital voltmeter may fill the bill.
A voltmeter, signal generator, and a few parts combine to make a powerful impedance measuring tool.