Non-invasive measurement of electrically small ultra-wideband and smart antennas

This paper presents a study into non-invasive measurements of electrically small ultra-wideband (SUWB) and narrowband electronically beam-steerable parasitic array radiator (ESPAR) smart antennas. To ensure accuracy and repeatability of traceable measurements of the radiation pattern performance of these antennas an electro-optical (EO) transducer and an Opto-Electric Field Sensor (OEFS) system are employed within a fully anechoic chamber. These allow the RF coaxial feed cable to be replaced by a much less intrusive fibre optic feed. To illustrate the benefits of the method, the numerical simulations of the radiation patterns are compared with the measured results obtained using (i) an EO transducer and (ii) a coaxial cable. Furthermore, a comparison between the measured and simulated Directivity of the SUWB antenna was performed to assess the non-invasiveness of the EO transducer over wide frequency range.