Impedance and Radiation Measurement Methodology for Ultra Miniature Antennas

This paper presents new measurement methodologies for ultra-miniature antennas. A first one is dedicated to the impedance measurement and the second one to the radiation measurement. Both methods are detailed focusing on an ultra-compact antenna design at 2.4 GHz, whose electrical dimensions, including the ground plane, are λ₀/25×λ₀/25×λ₀/62.5. Given the very small antenna size compared to the wavelength, measurements by means of conventional coaxial cable can affect the characterization results. The issues related to the use of a feeding coaxial cable in both simulation and prototype measurements are first discussed. Then, specific methods to deduce the isolated antenna properties are proposed. Both methodologies rely on the use of electromagnetic simulation to compensate perturbations introduced by the measuring device.