Flexible Efficient Quasi-Yagi Printed Uniplanar Antenna

A flexible quasi-Yagi printed antenna that is a compact, efficient directive radiator is demonstrated. The simple uniplanar design incorporates an arc-shaped strip, which serves as a near-field resonant parasitic (NFRP) element, and a coplanar-waveguide (CPW)-fed semiloop antenna. The simulated and experimental results that are in good agreement confirm the forward endfire nature of the antenna. The total electrical size is only 0.17 lambda(0) x 0.43 lambda(0), while having a high radiation efficiency to achieve a 5.76 dBi realized gain. A backward endfire version illustrates the radiation principles of the design. By mounting the uniplanar antenna conformally on a cylindrical structure, it is demonstrated numerically and experimentally that its radiation performance characteristics are maintained, confirming that only minor effects are introduced under bending conditions.