Investigation of surface wave propagation along a folded cylindrical helix array

The surface wave propagation along a closely-spaced folded cylindrical helix (FCH) array is investigated for the purpose of minimizing the size of the array element. It is found that the height of this surface wave guiding structure can be decreased from 0.24 λ_o to 0.06 λ_o by replacing the monopole with the folded cylindrical helix. The frequency band of the surface wave supported by the helix array is compared with that in the metal wire array. Furthermore, propagation constants are extracted by using ESPRIT algorithm, which indicates that a backward propagating surface wave is supported in the helix array structure.