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 (0.11 λ ), 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 (1.6 λ × 1.6 λ × 0.11 λ ). The DP is printed on the substrate with the wideband characteristic, and the MA operates at TM 50 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.