Printed log-periodic dipole antenna with an embedded UWB balun

A microstrip-fed planar log-periodic dipole antenna integrated with a printed ultra-wideband balun on the same PCB is presented. The in-band (1~6GHz) impedances and radiation performance are stable in simulated and measured results. A cross polarization discrimination (XPD) of 20dB is achieved. The stability of main beam direction in the radiation patterns reveals the fixed phase center and the balance of the wideband balun. The novel design of the meander shape along the quasi-transmission line in the antenna and the ground shape of the balun may contribute to the good XPD and bandwidth.