A method to increase the bandwidth of a series-fed dipole pair (SDP) antenna by using a parasitic strip pair director is presented. A conventional SDP antenna consists of two dipole elements having different lengths and a ground reflector, which are serially connected with a transmission line. In the proposed antenna, a parasitic strip pair director is appended to the conventional SDP antenna. Initially, a conventional SDP antenna that operates in a frequency range of 1.7-2.7 GHz is designed by optimizing the lengths of the elements (two dipoles and ground reflector) and the distances between these elements. Subsequently, a parasitic director containing a pair of strips is placed near the top dipole element to improve the bandwidth and gain of the conventional SDP antenna. Then, the effects of the location and size of the director on the impedance bandwidth and realized gain are investigated. A prototype of the proposed antenna is fabricated on an FR4 substrate, and its performance is compared with that of the conventional SDP antenna. The experimental results show that the proposed antenna has an enhanced bandwidth of 1.63-2.97 GHz (58.26%) and an increased gain of 5.6-6.8 dBi.
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