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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 (PCB), 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.

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This paper presents a novel MIC (microwave integrated circuit) design methodology, which consistently applies the H-plane discontinuity structures to integrate a multi-function microwave RF module using conventional PCB (printed-circuit-board) fabrication process. Two distinct types of waveguide, namely, microstrip and metallic rectangular waveguide, are simultaneously integrated on the same substrate(s) through the interface mode converters. An X-band MIC filter prototype, consisting of two H-plane mode converters and six H-plane waveguide slits, is built and tested, showing an attractive filter performance and a great potential for implementing the proposed MIC design methodology.

A compact dual-band rat-race coupler is proposed in this paper. By using composite right/left-handed (CRLH) transmission lines (TLs) and investigating all possible combinations of phase responses of the individual TLs in the coupler, a dual-band and miniaturized rat-race coupler was implemented. The dual-band rat-race coupler shows a 55% size reduction. This CRLH-based coupler is used as a modedecoupling network in a dual-band front-end MIMO system, along with a planar antenna array, to split two orthogonal radiation modes from the connected array. A pair of compact dual-band antennas were built and closely spaced to demonstrate pattern diversity by in-phase or out-of-phase excitations from the coupler. Good experimental isolation of the system, -29 dB at 2.4 GHz and -34.2 dB at 5.2 GHz, is exhibited verifying the desired decoupling property. Furthermore, pattern diversity in MIMO communications was observed by two measured orthogonal radiation patterns. Index Terms -Composite right/left-handed (CRLH) transmission lines (TLs), dual-band, MIMO systems, miniaturization, pattern diversity, rat-race couplers.978-1-4244-1780-3/08/$25.00