Miniaturised two-layer slit-patch structure for compact decoupling printed antenna array

Double-layer miniaturised structures are presented for reducing the mutual coupling between two closely spaced CPW-fed printed monopoles. The proposed structures employ two closely coupled layers, one made of conducting patches and another made of apertures (slits) in a ground plane. They are placed on either side of a very thin supporting dielectric substrate (55μm) with a rotation of 90° between the elements in order to produce maximum coupling. The dimensions of the proposed structures are optimised to produce maximum miniaturisation thereby occupying very little space on a compact ground plane. A microstrip line excitation is initially used for the efficient analysis and design of the structures. Two CPW-fed printed monopoles are subsequently employed to form MIMO system and the mutual coupling reduction is demonstrated. Results obtained in 3D electromagnetic simulation software (CST Microwave studio) are presented.