An Optimal Design of Compact Ring-Slot Antenna for a Rectenna System With Numerical Manipulation

An improved design of a compact ring-slot type antenna for a rectenna system, which has superior and controllable property in size, directivity, and harmonics suppression is proposed. The conventional ring-slot antenna is modified with the slits and side-cuts to control the resonant frequency band, the suppression band, and the creation of circular polarization. Seven design parameters are selected from the primary research and optimized using the particle swarm optimization method with a numerically manipulated fitness function. The proposed antenna shows desirable performances in simulation and also in measurement with a reduced size.