Backward Surface Wave Propagation and Radiation along a One-Dimensional Folded Cylindrical Helix Array

Abstract

Wave propagation along a closely spaced folded cylindrical helix (FCH) array is investigated for the purpose of designing compact array for energy transport and antenna radiation. It is found that the height of this surface wave guiding structure can be decreased from 0.24λ0to 0.06λ0by replacing the monopole element with the FCH. Both the propagation constant and the mode distribution of the dominant wave mechanism are extracted by ESPRIT algorithm, which indicates that a backward propagating surface wave is supported by the array structure. A compact backfire FCH antenna array is designed and measured based on the identified dominant wave mechanism.

Investigation of surface wave propagation along a multi‐coil wireless power transfer system

“…Next, the near field along the y direction at height z = 0 m is modeled as a summation of different traveling wave modes, each with a unique propagation constant β m , attenuation constant α m , and magnitude c m : where β m , α m , and c m can be extracted by applying ESPRIT, a super resolution spectrum estimation algorithm [8]. Previously, this method has been successfully applied to both wave propagation and antenna radiation problems . Figure shows the comparison between simulated near fields and fitted curve by the ESPRIT algorithm.…”

“… that the decay rate of EM energy along a 1D metal rod array is smaller than 1.5dB/ λ 0 , where λ 0 is the free space wavelength. Further investigations were conducted on surface wave propagations along such a wire array and a 1D folded cylindrical helix (FCH) array . However, the surface wave propagation along the closely spaced 1D coil array, the most well‐known WPT structure, remains to be investigated.…”