![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Two Non-Uniform High Impedance Surfaces (NU-HIS or \tapered HIS) are proposed against a Uniform HIS (U-HIS). All surfaces are one dimensional (1D) and made of parallel wires with a length a little less than λ/2 around the resonance frequency. To show the effect of the surfaces, a half wavelength dipole antenna is placed over four different surfaces, PEC, U-HIS, NU-HIS, and modified NU-HIS (MNU-HIS) while the dipole height is fixed and very close to the surface. These four EM problems are analyzed numerically by the method of moments (MoM), and the results are compared. It is concluded that MNU-HIS yields more bandwidth than NU-HIS, and also, NU-HIS yields more bandwidth than U-HIS, while overall structures in all cases have identical volumes and nearly identical gains. This effect is attributed to the decrease in the sensitivity of the surfaces to the angle of incidence obtained by applying non-uniformity.