Compact planar microstrip-fed quasi-Yagi antenna

A novel compact planar microstrip-fed quaisi-Yagi antenna is investigated. The feeding structure is directly realised by a microstrip line and has the advantage of avoiding the introduction of a balun, transition, tapered or truncated structures, thereby decreasing design complexity. The proposed antenna shows measured impedance bandwidth from 2.74 to 4.25 GHz for a return loss less than 10 dB, and exhibits 13 dB front-to-back (F/B) ratio, 15 dB cross-polarisation, 8.77 dB absolute peak gain, 60 half power beam width (HPBW) in the E-plane and 68 HPBW in the H-plane at the centre frequency (3.5 GHz). Measured results are in good agreement with electromagnetic simulations.