High Realized Gain Compact End-Fire Arrays: A Simple Design Solution

This paper presents a compact end-fire array with a high realized gain, featuring a simple planar design that offers a cost-effective solution for RFID applications and other uses. The synthesis strategy of this supergain array utilizes the Spherical Wave Expansion (SWE) theory. An array prototype consisting of four electrical dipoles spaced at 0.21λ, englobed in a total radiansphere of kr = 2.3, has been analyzed. By applying our optimization method, we demonstrate that tailoring the element feeding leads to significantly higher directivity and improved efficiency compared to conventional compact superdirective arrays. Additionally, the prototype is matched to a standard 50 Ω impedance using a printed T-match at the feeding point. The results demonstrate a notable realized gain exceeding 10 dBi.