Design of Low-Cost, Flexible, Uniplanar, Electrically Small, Quasi-Isotropic Antenna

A low-cost, flexible, uniplanar, electrically small, quasi-isotropic antenna with considerably simple structure is proposed and experimentally investigated in this letter. The antenna is composed of a pair of driven striplines and a split-ring resonator (SRR) with two extended strips on the same side of the substrate. The equivalent electric and magnetic dipoles generated by the SRR could realize omnidirectional radiation patterns oriented to x- and y-axis, respectively, with nearly the same amplitude of the realized gains. With the orthogonalized radiation patterns between the equivalent electric and magnetic dipoles, the measured results, in good agreement with the simulation values, demonstrated that the antenna has a quasi-isotropic radiation pattern with maximum gain difference around 3 dB in the whole sphere, an electrically small size (0.154 × 0.154 × 0.0004 λ
³
, ka = 0.68), and an overall efficiency 77%. Moreover, the performance characteristics of the antenna remains unchanged even when bending the antenna in different ways by conforming it on cylinders of various radii, proving its suitability for conformal applications.