In measurement of antennas, it's known that the method using the RoF(Radio on Fiber) instead of RF cable achieves accurate measurement of small antennas. The authors had shown it that a prototype of a small PD module which have a size of 16mm×16mm×5mm is practical. In this report, we made a test product of a small PD module which have a size of 9.5mm×9.5mm×3mm, and confirmed that the agreement between the measured and calculated radiation patterns of a monopole antenna on a small terminal is very good. Also, we indicate it by simulation that characteristics of a monopole antenna on a small ground are affected by the size of a PD module.