Near-field plates and the near zone of metasurfaces

A brief, tutorial account is given of the differences between the near and far regions of the electromagnetic field emphasizing the source-dependent behavior of the former and the universal of the latter. Field patterns of near-field plates, that is, metasurfaces used for sub-wavelength applications, are discussed in some detail. Examples are given of fields that decay away from the plates in an exponential manner, a ubiquitous feature of many interface problems, and metasurfaces for which the decay is not exponential, but algebraic. It is also shown that a properly designed system of two parallel near-field plates can produce fields that exhibit pseudo minima, which are potentially useful for near-field tweezer-like applications.

Automated summary

The tutorial discusses the differences between the near and far regions of the electromagnetic field, highlighting the source-dependent behavior of the former and the universal nature of the latter. It also delves into the field patterns of near-field plates used for sub-wavelength applications, providing examples of exponential and algebraic decays. Additionally, it demonstrates how a properly designed system of two parallel near-field plates can generate fields with pseudo minima, which could be beneficial for certain applications.