A low-profile four-degrees of freedom antenna by collocating a ±45°-polarized dipole and a dual-polarized microstrip antenna with broadside radiations

Abstract

This letter proposes a novel four-degrees of freedom (4-DOFs) antenna for 5.8 GHz wireless local area network band communications. The proposed antenna realizes 4-DOFs with a low profile (0.11λ), which is composed of ±45°-polarized dipole (DP), an artificial magnetic conductor (AMC) reflector, and a dual-polarized slot-loaded microstrip antenna (MA). The whole size of the proposed antenna is 83 mm × 83 mm × 5.9 mm (1.6λ × 1.6λ × 0.11λ). The DP is printed on the substrate with the wideband characteristic, and the MA operates at TM₅₀ mode. The AMC reflector operating for the DP is designed for the low profile, causing the low isolations between the DP and the MA. The broadside radiation with 4-DOFs is first reported. The envelope correlation coefficients are lower than 0.07, and the DOFs are 3.75. The measured results are in accord with the simulated results.