Compact batteryless photodiode module for measurement of radiation characteristics

Antenna measurement using the radio on fiber method instead of coaxial cables is widely used to accurately measure the characteristics of small antennas. The authors have shown that a prototype of a photodiode module, which is 16 mm × 16 mm × 5 mm in size, is practical for small antenna measurements. In this study, we fabricated a more compact photodiode module, which is 9.5 mm × 9.5 mm × 3 mm in size, and measured radiation characteristics using this prototype. We confirmed good agreement between the measured and calculated radiation patterns of a monopole antenna on a small terminal. The effect of miniaturization of the module was also clarified using simulations.