Design and evaluation of a class of miniaturized metal-backed antenna

This paper presents a two-layer mushroom-like reactive impedance surface (RIS) and its application to patch antenna miniaturization. RIS, known as meta-substrate, have shown the ability to miniaturize printed antennas with omni-directional radiation pattern, when served as the substrate for the antenna (H. Mosallaei and K. Sarabandi, IEEE Trans. Antennas Propag., 52, 9, 2403-14, 2004). However, the area of conventional RIS substrate usually has to much larger than that of miniaturized antenna, since the cell´s dimension is comparable with the antenna, even using a high dielectric constant of 10.2 or 25. The proposed compact two-layer RIS can achieve 76% lower frequency than conventional one-layer RIS with the same size, whose cell dimensions are limited within λ₀/45 in length and λ₀/100 in height while the dielectric constant is kept below 3.5. This makes it possible to design a miniaturized antenna over an RIS substrate with the same size as the antenna itself.