Experimental Demonstration of Artificial Magnetic Conductors Constructed of Magnetically Coupled Helices

Broadband Artificial Magnetic Conductors Constructed of Magnetically Coupled Elements

“…2. Geometries of the AMC unit cells and their AMC performance for a) conventional patch structure [14], b) low frequency patch structure [14], and c) helical structure [15].…”

“…The previously published results provide a wide range of possible parameters with operational band ranging from 10% to 40% compared to the resonant frequency while the thickness varies from 5% to 7% of the wavelength [14]. It has been recently demonstrated that AMCs can be constructed of magnetically coupled helices [15], and structures that provide 31% operational band while comprising 5% of the wavelength have been suggested.…”

Near-field electromagnetic coupling between helices

“…The use of helices with different handedness provides greater control over coupling values for a set distance between elements that may be used in cases where an exact value of coupling is required to obtain the theoretical maximum performance, for instance, the design of artificial magnetic conductors [21]. The analytical approach that may be used to find the coupling coefficients required for a particular AMC response is found in [28].…”

“…The coupling coefficients between helices can be adjusted for the particular applications depending on the performance requirements. For instance superdirective antennas can benefit from elements with low quality factor [20]; a small number of turns is necessary for artificial magnetic conductor structures [21]; while large negative values of coupling provided by capped helices allows one to design broadband surfaces with negative mode index [22].…”

“…Because of this, helices have been optimised and used to control the effective properties of metamaterials such as the dielectric, magnetic, and chiral susceptibilities [12,13] the reflectivity, transmissivity, and absorption of metamaterial layers [14][15][16][17][18], operational bandwidth [15] as well as circular polarization conversion [19]. Moreover helical elements have been also used for superdirective antenna applications [20], to construct artificial magnetic conductors [21], and to design metasurfaces with broadband negative mode index [22].…”