Left-handed transmission lines have been characterized by electro-optic sampling. The transmission lines used a coplanar strip technology periodically loaded by series capacitances and shunt inductances printed by electron-beam lithography onto a low-κ substrate. The experiments by optoelectronic sampling were conducted using low-temperature-grown GaAs and AlGaAs patches for probing the time-domain transmission properties. The devices exhibit a high-frequency response above 100 and up to 400 GHz which shows direct evidence of a backward propagation by tracking the time dependence of transmitted signals and phase analysis.
-This paper presents two metamaterial-inspired solutions to mitigate the scan blindness effects in a phased array antenna. In the first solution, portions of a bed of nails are introduced in the radome to prevent the excitation of surface waves. In the second solution, a superstrate metasurface is designed to synthesize a permittivity tensor optimized to achieve a wide angle impedance matching. In both approaches, the numerical simulations are successfully compared with measurements of a phased array antenna prototype with 100 elements. The wire medium-based solution reveals an effective way for reducing the blind-spot in a wide bandwidth, while the metaradome has been found less suitable for the same purpose.
In this work, a metaradome based on a fakir's bed of nails is designed and tested in order to suppress the blind directions of a 100-element antenna array. The antenna is a microstrip array designed to operate in X-band. The fakir's bed metamaterial-like was first approximated using analytical formulas before a full-wave numerical optimization. Experimental results are exposed and confronted to numerical results. They show a significant reduction of the blind spot subsequent to the metaradome addition
A new characterization technique for metamaterials is presented for measuring electric-fi eld patterns. The electric-fi eld frames are obtained through a thermoemissive fi lm, located in the near-fi eld domain of the metamaterial. Using an infrared camera, sub-wavelength details can be identifi ed. We applied this technique to antennas based on composite right/left-handed transmission lines (CRLH TLs), also called zeroth-order-resonator (ZOR) antennas. The electric-fi eld distributions of zeroth-order-resonator antennas at frequencies corresponding to longitudinal modes between 4 GHz and 12 GHz were determined. These fi eld frames were in agreement with numerical results obtained by fi nite-element analysis. This paper addresses techniques for the experimental validation of numerical computations.
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