A rigorous measurement technique using native signals to characterise the radia-tion patterns of single receiving antenna wireless communication systems is presented. A scalar pattern measuring process, robust to modulated and bursty signals, has been validated against the traditional vector network analyzer pattern measuring method. The receiver comprised a sin-gle receiving antenna and a calibrated RF spectrum analyzer. Initial evaluation used a Bluetooth signal emulator test device comprising a monopole antenna, extracted from a MICAz wireless sensor network platform, and fed by a RF signal generator. Following a rigorous assessment of the technique, it was applied to investigate the radiation pattern from a MICAz sensor mote. The results show good repeatability and demonstrate that the technique is robust and would be valuable for assessing the performance of embedded radio system designs.