engleski

Application of Wire Media in Antenna Technology

This paper reviews the results of experimental investigation of radiating structures based on plasma-like wire media, undertaken at University of Zagreb. It is shown that all three regions of the dispersion curve of wire media, namely the Epsilon-NeGative (ENG) region, the Epsilon-Near-Zero (ENZ) region and the Epsilon-PoSitive (EPS) region, can be successfully utilized in antenna applications. The phenomenon of gain increase of an antenna embedded in wire medium, based on ultra-refraction in ENZ region, was investigated in 10 GHz band. The results revealed that the use of ultra-refraction may be a practical approach in the case of low-directivity radiators such as simple monopole antennas. Another example of the utilization of the ENZ region deals with the shortened horn antenna with embedded wire-medium-based ENZ slab operating in 10 GHz band. Two pro-totyped shortened horn antennas (labeled as horn I and horn II) had lengths of 52% and 33% of the length of the optimal horn, respectively. Measured gain was found to be very similar to the gain of the full length optimal horn (within 0.1 dB), but in a narrow band (12% for horn I and 8% for horn II). The last example deals with a scanning leaky-wave antenna operating at 10 GHz, based on a waveguide filled with double-wire medium operating in all three regions of the dispersion curve. These three regions correspond to three different modes of propagation in the waveguide: the backward-wave mode, the forward-wave mode and the mode with infinite wavelength. Experimental results revealed the possibility of main beam scanning within an angle of +- 60 degrees from broadside direction.

wire media, antenna, metamaterial

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