The development of a slotted substrate integrated waveguide antenna with an epsilon near zero (ENZ) material is presented. Here, an ENZ waveguide structure is used in the design. The ENZ material is used to realize unconventional tunneling of electromagnetic energy with ultra-thin subwavelength channels and it is considered to attain a highly directive narrow band antenna. The effect of the various parameters of the antenna is studied by simulation. A prototype is fabricated and the measurement results are compared with the simulated values.

A novel idea for generating directional electromagnetic beam using a metamaterial absorber for enhancing radiation from a microwave antenna in the S-band is presented herewith. The metamaterial structure constitutes the well-known stacked dogbone doublet working in the absorption mode. The reflection property of the dogbone metamaterial absorber, for the non-propagating reactive near-field, is utilized for achieving highly enhanced and directional radiation characteristics. The metamaterial absorber converts the high-spatial reactive spectrum in the near-field into propagating low-spatial spectrum resulting in enhanced radiation efficiency and gain. The gain of a printed standard half-wave dipole is enhanced to 10 dBi from 2.3 dBi with highly directional radiation characteristics at resonance.

The detailed experimental and simulation studies of the stacked dogbone metamaterial particles are presented in this article. Besides the conventional left handed propagation mode, it is observed that the structure supports Fabry-Perot resonant modes and the excitation of this mode can be identified from the right handed resonant tunnel band in the dispersion diagrams. It is shown that the coupling between the Fabry-Perot and left handed resonant modes gives flat tunnel band characteristics in the dispersion diagram and is associated with huge electromagnetic absorption. The spectral response can be tailored by varying the stacking thickness of the sample making it suitable for microwave absorption and left handed transmission applications. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1347-1353, 2016

The theory of diffraction limit proposed by H.A Bethe limits the total power transfer through a subwavelength hole. Researchers all over the world have gone through different techniques for boosting the transmission through subwavelength holes resulting in the Extraordinary Transmission (EOT) behavior. We examine computationally and experimentally the concept of EOT nature in the microwave range for enhancing radiation performance of a stacked dipole antenna working in the S band. It is shown that the front to back ratio of the antenna is considerably enhanced without affecting the impedance matching performance of the design. The computational analysis based on Finite Difference Time Domain (FDTD) method reveals that the excitation of Fabry-Perot resonant modes on the slots is responsible for performance enhancement. (C) 2015 Author(s).

An experimental realization of resonant toroidal dipole excitation in the microwave regime is presented in this paper. The metasurface proposed herewith is an asymmetric double split-ring resonator exhibiting Fano-like resonance profile. One could observe that cascading the metasurface results in near-field transverse and longitudinal coupling creating dual-band toroidal moments on the structure. This planar scheme will simulate the development of enhanced light-matter interaction, electromagnetic wave slowdown and sensor design. Here we report the experimental realization of the phenomenon in the S-band frequencies, and the results are verified using multipole scattering analysis.

Achieving super-resolution beyond the diffraction limit is an intriguing research topic over the last century. In this paper, the split-ring resonator array-based evanescent amplification in the microwave regime is implemented for strongly enhancing radiation from an electrically small radiator. The electrically small radiator considered here is a chip inductor loaded open coplanar waveguide antenna. This weakly radiating source when placed in the vicinity of split-ring resonator array, it is seen that the radiated power could be greatly enhanced. The split-ring resonator array working under the magnetic resonant excitation could amplify evanescent fields emitted by the source. Field probing reveals that the split-ring resonator array could convert the amplified evanescent waves into propagating ones resulting in significantly enhanced radiation from the source.