Modified broadband quasi‐Yagi antenna with enhanced gain and bandwidth

This article presents a method for improving the gain and bandwidth of a microstrip‐fed broadband planar quasi‐Yagi (QY) antenna.To obtain a better and more stable gain with little variation over a broad frequency band, we used a planar QY antenna with strip‐type elements (a driver dipole and two directors) that had unequal widths and unequal spacing between them. First, to achieve a broad bandwidth of over 50%, a wide strip is used as a nearby director placed very close to the driver dipole. Then, to enhance and stabilize gain over a required frequency band, a narrow strip director and a ground reflector are appended to the driver with a nearby parasitic director. We systematically explain the effect of each element on the input impedance and the realized gain. To validate this proposed design, a QY antenna with a frequency band from 1.75 to 2.7 GHz and a gain of over 5 dBi was designed, then fabricated on an FR4 substrate, and tested. The results show that the fabricated antenna performs well, with a broad bandwidth of 60.4% (1.53–2.85 GHz), a stable gain between 5.38 and 6.41 dBi, and a front‐to‐back ratio of over 10 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:406–409, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27325