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Metamaterials (MMs) became a very actual topic in the present research interest field, due to their unusual but interesting characteristics, not encountered in nature (Veselago, 1968)(Engheta & Ziolkowski, 2005). A way to obtain media having MM characteristics is to develop circuits which, under certain conditions, model the MMs properties. Using different lattice structures or periodic repetition of unit cells, different types of two-dimensional MMs have been suggested (Sievenpiper et. al., 1999; Caloz & Itoh, 2003). A particular class of MMs consists of artificial LH (Left-Hand) transmission lines, which may be obtained using series capacitors and parallel connected inductors. With this approach and using SMDs (surface mounted devices), circuits such as branch couplers (Lin et al., 2003) and ring couplers (Okabe et al., 2004) operating up to a few GHz, have been reported. The main advantage of these circuits compared to the classical ones is the dual frequency response for any two frequency ratio. For higher microwave frequencies, it is more convenient to replace SMD capacitors and inductors with interdigital capacitors and short-ended transmission lines, respectively, in microstrip or CPW configuration. Taking into account the series equivalent inductance of the capacitors and the parallel equivalent capacitance of the short-ended transmission lines (working as inductors, at their own resonance frequency), CRLH (Composite Right/Left Handed) cells are obtained (Lai et al., 2004). The CRLH cells open a new class of devices and applications such as backward-wave directional couplers (Caloz et al., 2004), tunable radiation angle and beamwidth …
Publication date: 
1 Mar 2010

Stefan Simon, Romolo Marcelli, Giancarlo Bartolucci, Florea Craciunoiu, Andrea Lucibello, Giorgio De Angelis, Andrei A Muller, Alina Cristina Bunea, Gheorghe Ioan Sajin

Biblio References: 
Advanced Microwave and Millimeter Wave Technologies Semiconductor Devices Circuits and Systems