Abstract: This paper presents a broadband antenna for brain activity detection. The antenna is a microstrip monopole, which consists of a slotted rectangular wide seam, a triangular patch and a reflector. The antenna is matched to the human head tissue directly. The -10 dB return loss bandwidth covers the operating frequency range of 2.3-8 GHz. And the electromagnetic energy transfer characteristics and electric field distribution in the brain is simulated. The results show that the on-body matched antenna has better penetrating ability inside human's head than the conventional antenna, and appreciable intensity of electric field can still be found in cerebral cortex. The simulated and measured results are consistent with each other very well. The antenna features small size, simple and compact structure. Meanwhile, it meets the design requirements of antenna array well in brain activity detection system.