Semi-elliptical dipole antenna for RF energy scavenging

A method to miniaturize a planar semi-elliptical dipole antenna in the FM band (88-108 MHz), is presented. The proposed method modifies the antenna´s structure, having dimensions of a roof tile (L = 432 mm × W = 345 mm), so that an array can be created. The first step was to use slots to meander the surface current path of the antenna lowering the resonating frequency and size. The second step involved using a passive matching network to further reduce the overall dimensions of the antenna with minimal loss. It was shown by using both slots and a matching circuit a size reduction of 0.311 × 0.251 was achieved with a bandwidth of 6% and a gain of 0 dBi at 100 MHz. This antenna can be used for RF energy scavenging applications.