摘要： The phase profiles of the field components and the scattering widths of a circular cylinder with coating or core made of epsilon-near-zero (ENZ) and double-near-zero (DNZ) mediums for normally incident planewave are investigated. It was found that the axial components generally had a uniform phase inside a bare ENZ or DNZ cylinder for both the TE and TM polarization states in the cylinders with small as well large radii. The azimuthal components could have a slowly varying phase only for large cylinders. When the ENZ or DNZ mediums were used as cores or coatings, the uniformity of the phases decreased. Generally, DNZ mediums have more slowly varying phases than the ENZ mediums, and the TE polarization has a more uniform phase than the TM polarization. The scattering widths were found to be the smallest for DNZ-coated dielectric cylinder and the largest for dielectric-coated ENZ or DNZ cylinder. This study can provide a guideline for the thickness of the near-zero index medium in device design since different thicknesses are needed for achieving uniform phase inside the ENZ or DNZ medium for a particular component of the electric and magnetic fields in the three configurations studied in this paper.