Theory and Realization of a Pattern-Reconfigurable Antenna Based on Two Dipoles

A front-to-back pattern-reconfigurable antenna based on two dipoles is investigated. The theory for a front-to-back pattern reconfiguration is analyzed. The front-to-back ratio (F/B) is improved by using two folded dipoles. The pattern-reconfigurable antenna is realized by switching two PIN diodes with two broadband baluns. Two parasitic elements are introduced for the improvement of impedance bandwidth and pattern bandwidth. A shorter dipole is added to each folded dipole for further enhancing the pattern bandwidth. Experimental results show that the pattern-reconfigurable antenna achieves a bandwidth of 31.4% for return loss > 10 dB and a pattern-bandwidth of 20.8% for F/B > 10 dB and 11.5% for F/B > 15 dB.