Wideband double-dipole yagi-uda antenna fed by a microstrip-slot coplanar stripline transition

Abstract

This paper describes a wideband double-dipole Yagi-Uda antenna fed by a microstrip-slot coplanar stripline transition. The conventional dipole driver of a Yagi-Uda antenna is replaced by two parallel dipoles with different lengths to achieve multi-resonances, and a small, tapered ground plane is used to allow flexibility in the placement of a pair of reflectors for effective reflection of back-radiated electromagnetic waves. The measured bandwidth of the antenna was 3.48-8.16 GHz for a-10 dB reflection coe±cient, with a flat gain of 7:4 ± 0:4 dBi. A two-element array of these antennas was also constructed, with a center-to-center spacing of 36mm (0:72λoat 6 GHz) and a common reflector between the elements. The two-element array had a measured bandwidth of 3.56-792 GHz, a gain of 8.40-10.43 dBi, a cross-polarization level of <-15 dB, and a mutual coupling of <-16 dB within the impedance-matching bandwidth.