A compact circularly-polarized array based on superdirective elements

In this paper, a new strategy for designing compact Circularly-Polarized (CP) arrays is proposed. This approach consists of using small parasitic superdirective arrays as unit elements. An array is designed for 866MHz RFID band and a parametric analysis on the inter-element distance is performed to highlight the trade-offs between the antenna-dimensions, -directivity and radiation efficiency. For total dimensions of 220 × 220 × 25.8mm
³
(0.58λ × 0.58λ × 0.075λ), the array has a CP directivity of 10.3dBic and a radiation efficiency of 38.5%.