Measurement of HF antenna impedances

This paper describes the design of an antenna reflection coefficient measurement system. The prototype measures the real and imaginary components of the reflection coefficient (ρ) in the frequency range 1.8 MHz-30 MHz. The system is able to operate with high level ambient signals present at the antenna feed point, whilst maximum measuring signal power delivered to the antenna is limited to 1 μW. An experimental evaluation of the prototype is described. The measurement error is equivalent to less than 5% in magnitude |ρ|, and 4° in phase <ρ