Planar Yagi–Uda Antenna Array Based on Split-Ring Resonators (SRRs)

A novel planar Yagi-Uda antenna is presented in this letter. The proposed antenna uses electrically small resonators as radiating elements that behave as short electric dipoles. Its radiation pattern, gain, front-to-back ratio, and efficiency are maintained close to that of a Yagi-Uda antenna of stacked half-wavelength dipoles. However, its physical dimensions are considerably reduced. The choice of the resonant particle and its radiation properties, along with the antenna structure, are discussed. Simulated results show a good impedance matching (-29 dB) at the working frequency of 5.5 GHz for a 15-elements antenna, as well as a high gain (11.5 dBi). These characteristics are experimentally validated and compared to that of other Yagi-Uda designs from the literature.