Electrically Small GPS L1 Rectennas

An electrically small, metamaterial-inspired near field resonant parasitic (NFRP) planar protractor antenna is designed for operation, as a proof-of-concept choice, at the GPS L1 frequency (1.5754 GHz). It is based on electric coupling between a capacitively loaded loop (CLL) NFRP element and a driven monopole. Modified versions are then integrated with simplified rectifying circuits to realize two electrically small GPS L1 rectenna systems. The complex impedance matching capabilities of an NFRP antenna allow matching it directly to a rectifying circuit, reducing the overall rectenna size. Simulation results of the | S₁₁ | values, radiation efficiencies and patterns, and Q-ratios are provided. For the low, 0-dBm input power level, the measured rectifying efficiencies of the larger (ka = 0.808) and 25% smaller (ka = 0.604) version are, respectively, 78.0% at 1.5754 GHz and 67.9% at 1.55 GHz.