Eccleston, KW2023-04-192022-11-192023-022022-11-091751-87258M1NM (isidoc)https://hdl.handle.net/10182/16050It is shown that anomalous boundary conditions at the surface of a negative-refractive-index metamaterial planar lens severely diminishes the resolution of the lens when its relative permittivity and permeability are both −1. Anomalous boundary conditions arise in practical microwave metamaterials that are typically a periodic array of identical unit cells comprising dielectric and conducting elements. For a unit-cell size much smaller than the wavelength, homogenised permittivity and permeability are the constituent parameters of the average fields. Average fields vary on a scale larger than the unit cell size compared to localised fields associated with the constituent elements. Unlike the tangential components of the localised field, tangential components of the average fields are discontinuous across the surface of such materials. This anomalous boundary condition at the lens surface must be described by generalised sheet transition conditions. This study develops expressions for the negative-refractive-index lens optical transfer functions, as a function of spatial frequency, for transverse-electric waves, that account for anomalous surface boundary conditions. Both the simulations and experimental data are used to verify the expressions at a frequency of 3 GHz.pp.118-131en© 2022 The Authors.anomalous boundary conditionscomposite materialsgeneralised sheet transition conditionsmetamaterialsnegative-refractive-indexpermeabilitypermittivityJournal Article10.1049/mia2.123251751-87332023-03-30ANZSRC::400608 Wireless communication systems and technologies (incl. microwave and millimetrewave)ANZSRC::400601 Antennas and propagationANZSRC::401602 Composite and hybrid materialsANZSRC::460207 Modelling and simulationANZSRC::4006 Communications engineeringANZSRC::4008 Electrical engineeringANZSRC::4009 Electronics, sensors and digital hardwarehttps://creativecommons.org/licenses/by/4.0/Attribution