Small Antennas Based on CRLH Structures: Concept, Design, and Applications

Recent growth in the use of wireless wide-area networks (WWAN), the adoption of broadband wireless local-area networks (WLAN), and consumer demand for seamless global access has pushed the wireless industry to support most broadband wireless standards. These are supported in different geographical areas by supporting multi-band and multimode operation in cellular handsets, access points, laptops, and client cards. This has created a great challenge for engineers. It has pushed RF and antenna design beyond the capabilities of current technologies, opening the door for creative solutions that are 1) multi-band, 2) low profile, 3) small, 4) better performing (including MIMO), 5) accelerate time to market, 6) low cost, and 7) easy to integrate in the devices listed above. Conventional state-of-the-art antenna technologies satisfy a subset of these seven criteria; however, they hardly satisfy all of them. In this paper, we apply composite right-left-hand “CRLH-based” RF design to print penta-band handset antennas directly on the printed circuit board (PCS), and balanced-antennas for Wi-Fi access points. Full active and passive performance is presented, while describing key benefits of metamaterial antennas. We also analyze in detail how these antennas operate, while focusing on the main left-handed (LH) mode that enables antenna size reduction, and the ability to print them directly on the printed circuit board.