Electronically controlled metamaterial-based leaky-wave transmission-line for conformal surface applications

In this paper a novel multifunctional electronically controlled conformal metamaterial-based transmission-line (TL) is presented. The proposed structure is a 25 unit-cell composite right/left-handed (CRLH) TL that is conformed on a cylindrical surface with a radius of 25 cm. This TL supports both guided-wave mode and radiation mode under its fundamental mode operation. Varactor diodes are introduced in the unit-cells to electronically control its guided and radiation characteristics. By applying different reverse-bias voltages the capacitance of the unit-cell is tuned. It will be shown that the proposed TL has the ability to operate partially in the slow-wave (SW) region and partially in the fast-wave (FW) region by applying proper biasing voltages to the different sections of the TL. Therefore, it has a unique radiation aperture selectivity function which results in controlling the radiation angle and beamwidth at a fixed frequency. In addition it will be shown that this electronically controlled conformal CRLH TL has the capability to compensate for the conformation effect by adjusting the biasing voltages properly. The proposed method allows the conformal structure to refocus its radiation main beam and have a comparable performance as the planar version.