Authors: Mohammed Reza M. Hashemi and Tatsuo Itoh
Source: FERMAT, Volume 18, Article 3, Nov.-Dec., 2016
Abstract: In this paper, novel dispersion engineered conformal metamaterial-based leaky-wave antennas (LWA) based on composite right/left-handed (CRLH) concept are being reviewed. As a planar CRLH LWA is conformed on a curved surface, the radiation characteristics of LWA is distorted. The effect of conformation on a CRLH LWA is investigated. A dispersion engineering method is presented to compensate for the conformation effect and obtain radiation characteristics comparable to the planar version for both convex and concave surfaces. Using the dispersion engineering technique an electronically controlled multifunctional CRLH transmission-line (TL)/LWA will be presented. The slow-wave and fast-wave characteristics of this CRLH device is electronically controlled by incorporating varactor diodes in the CRLH unit-cells. It will be shown that by using the developed dispersion engineering compensation technique along with applying the proper reverse bias voltage to the varactor diodes of each unit-cells and tuning the capacitance of each unit-cell the effect of conformation is compensated. Furthermore, it will be shown that by having certain section of the CLRH device operating in the slow-wave mode and the remaining sections in the fast-wave mode, through applying the proper reverse-bias voltage to the varactor diodes, and by changing the location of the fast-wave section along the device a radiation aperture selective functionality is introduced. Thus, the radiation angle and the beamwidth of the LWA is electronically controlled at a fixed frequency.
Index Terms: Composite right/left-handed (CRLH), metamaterials, conformal antenna, electronically controlled, leaky-wave (LW).
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