Novel multiband autonomous impedance restoration antenna system by using a probe

Recently the number of operating frequency bands for a single mobile terminal has been increasing, while the size reduction for a built-in antenna is required. Therefore, it has become more difficult for the antennas built-in mobile terminal to cover all frequency bands with high efficiency. Moreover, the body of the user and the other objects in the vicinity of the mobile terminal usually detune the antennas. In this paper, a novel multiband autonomous impedance restoration antenna system by using a tiny probe has been proposed. The antenna is a 60mm×10mm sized planar monopole on the same plane with the 60mm×90mm ground plane and covers the following wireless communication system bands: LTE (704-746MHz and 2500-2690MHz), GSM850 (824-894MHz), EGSM (880-960MHz), DCS (1710-1880MHz), PCS (1850-1990MHz) and UMTS (1920-2170MHz). It has been shown that the VSWR and total efficiency η_tot(transmission coefficient T×radiation efficiency η_rad) of the antenna are optimized as the received power of a probe is maximized regardless of frequencies.