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The intrinsic frequency dispersion has usually been considered as a relevant drawback of metamaterials, limiting their application to narrowband microwave components. However, we have recently demonstrated that a particular metamaterial-based lens, consisting of a combination of an epsilon-near-zero (ENZ) material and air, is able to enhance the gain of short horn antennas over a broad frequency range...
The intrinsic frequency dispersion has been usually considered as a relevant drawback of metamaterials, limiting their application to narrowband microwave components. However, it has been recently demonstrated that a particular metamaterial-based lens, consisting of a combination of an epsilon-near-zero (ENZ) material and air, is able to enhance the gain of short horn antennas over a broad frequency...
Several designs of structures that behave similarly to plasmonic spheres but in the RF regime (“RF replicas”) have been introduced recently. These replicas enabled “scaled RF experiments” of future optical 1D and 2D plasmonic structures. However, an investigation of the 3D structures was not possible due to inherent anisotropic nature of RF replica. Here, this drawback is overcome by a novel design...
Recently proposed DB boundary is a hypothetical surface, on which the cancelation of normal components of the D and B fields occurs. Such a surface behaves as either PEC or PMC plane for the incident plane wave of TE or TM polarization, respectively. A possible realization of a DB surface, based on a slab made out of known metamaterial structures with resonant inclusions (SRRs and inductively loaded...
Several different interpretations of counter-intuitive phenomenon of subwavelength backward-wave propagation in SRR-loaded waveguide are available in open literature. Some of those ideas are reviewed and compared in this paper. Special focus is put on the homogenization theory as a validating tool for the equivalence between a SRR-loaded waveguide and a waveguide filled with continuous anisotropic...
An idea of magnetic metamaterial particle at optical frequencies, based on a circular arrangement of plasmonic spheres has been proposed recently. Unfortunately, experimental verification of this interesting idea is very difficult and expensive due to current limitations of nanotechnology. On the other hand, there is also recently published approach with scaled experiments that make use of RF structures...
This paper reviews recent numerical and experimental investigation of application of wire-based ENZ metamaterials in miniaturization of waveguide horn antennas, undertaken at University of Zagreb. Two representative examples of prototyped shortened horn antennas that operate in 10 GHz band are described: the horn with embedded single-wire ENZ slab and the horn with embedded double-wire ENZ slab. These...
Recent numerical study predicted phenomenon of a gain increase of a shortened horn antenna with the help of embedded double-thin-wire ENZ metamaterial slab. Here, we perform an experimental investigation of shortened horn antenna (length of which spans 52% of the length of optimal horn) with much simpler single-wire ENZ slab operated in 10 GHz band. Measurements revealed gain increase of more than...
Recent numerical study indicated possibility of use of a double thin-wire metamaterial slab as a flat lens that can be embedded into a horn antenna. This led to the construction of the horn, the gain of which is almost equal to the gain of an optimal horn across the moderate bandwidth, but with the substantially shorter length (down to 52% of the original length). Here, we perform both numerical and...
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