Reconfigurable composite right/left-handed transmission line antenna based Hilbert/Minkowski stepped impedance resonator for wireless applications

The subject matter of the article is the analysis and design of a via free metamaterial antenna based on a composite right/left-handed transmission line (CRLH-TL) structure. The goal is to design a high-gain antenna with dual-band resonance capable of changing its resonance frequency and gain adaptively. The tasks to be solved are creating an antenna with a high gain-bandwidth product along the operated band, achieving adaptive frequency reconfiguration and creating a direct antenna modulation process using active elements. The simulation methods used are: the proposed antenna is designed by integrating a CRLH-TL structure to a 1D array based on two types of unit cells: The first unit cell is realized from a Hilbert curve of the 3rd order, and the second one is based on the 1st order of Minkowski – stepped impedance resonator (SIR). The antenna parts are printed on a Taconic RF-43 substrate with thickness = 1.57 mm. The following results were obtained: The Hilbert/Minkowski–SIR antenna achieved dual-band operation with a maximum gain equal to 14 dBi and 18 dBi at 5 GHz and 5.5 GHz, respectively. Furthermore, by changing the states of the PIN diode, an amplitude shift keying direct antenna modulation process is achieved; for instance, at 5 GHz, the antenna can change its gain directly in the range from (12-14) dBi with good impedance matching. Finally, the proposed antenna shows a low profile and operates at different frequency bands within sub-6 GHz applications. Conclusions. The simulation results indicate that such antenna performance enhancement is the result of eliminating via conduction losses, ground plane capacitance losses and suppressing surface wave reflections due to the Hilbert/Minkowski SIR introduction.