Wideband Antenna Design Based on the Analysis of Equivalent Resonant Circuits

Firstly, conditions of impedance bandwidth expansion using series and parallel resonant circuits are studied in this paper. Then series resonant circuit and parallel resonant circuit are composed to form multi-resonance circuit and realize multi-resonance peaks. With the consideration that the equivalent resonant circuits of the electric and magnetic dipole antennas are series and parallel resonant circuits, respectively, it is possible to design wideband multi-resonance antennas by combining electric dipoles and magnetic dipoles. As an example, a multiple dipoles antenna is designed. The impedance bandwidth of the proposed antenna is 26.3% and the gain over the operating band is stable.