Sub-wavelength near field imaging using a non-resonant slot with a wire insert

In this paper we study sub-wavelength imaging by a new type of probe comprising a single non-resonant slot cut into a metal plate with an immersed lump loaded wire inclusion. With this simple arrangement when the E vector of the incident field is polarized along the long slot edge we show numerically and experimentally that the transmitted near field can be enhanced up to 25 dB with respect to the unloaded slot transmission and superior near squeezing results in 0.14λ FWHM at 0.1λ from the slot. In addition we show that near field spatial compression is a function of the lumped element impedance used to bring the wire slot arrangement into resonance. Using this novel probe arrangement an imaging setup based on the reflection measurement from a loaded slot is proposed. The characteristic resolution of two scattering (passive) half wavelength wires is shown to be better than λ/4 at the distance 0.1λ. The work that we propose is an advance on previously slot based near field art which is briefly summarized below.