A novel balun structure for dipole antenna,which is based on the current distribution on parallel microstrip lines and the emission cancellation characteristic of close equal and opposite currents,is proposed.The principle of the balun structure is first elaborated and verified.Then,a dipole antenna with resonance at 2.45 GHz is constructed using the balun and its radiation pattern is measured.The simulated and measured reflection coefficients(S_(11))of the antenna are in good agreement 2—3 GHz.The relative bandwidth with an S_(11) of below-10 dB is more than 25%.The antenna also shows a good radiation pattern at 2.45 GHz.The proposed structure can provide a new balun design method for dipole antennas.
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