Metamaterial-based dual-band six-port front-end for direct digital QPSK transceiver

A composite right/left-handed (CRLH) transmission line (TL) dual-band (DB) six-port front-end is presented. The two key components in the six-port front-end, i.e. a 90deg hybrid coupler and a power splitter, are designed using CRLH TL sections and therefore are capable of operating at two arbitrary frequencies. The novel DB six-port front-end is well suited to a direct digital transceiver