A simple approach for reducing the mutual coupling in two closely spaced electrically small antennas (ESAs) is proposed based on the general idea of field cancellation. The antenna array consists of two metamaterial-inspired small printed monopole antennas. The mutual coupling is reduced by self-cancellation of the induced common ground and near-field currents, without introducing additional structures. A fabricated prototype of a two-element array with an edge-to-edge separation of ?0/30.6 (or center-to-center separation of ?0/13.6) yields a measured mutual coupling of |S11| better than -18 dB across the impedance band of |S11| < -10 dB, which is significantly better than the -9 dB level of the original array.

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A Simple Approach for Reducing Mutual Coupling in Two Closely Spaced Metamaterial-Inspired Monopole Antennas

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.

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

Antennas for wireless communications based on metamaterial (MTM) structures to arrange one or more antenna sections of an MTM antenna away from one or more other antenna sections of the same MTM antenna so that the antenna sections of the MTM antenna are spatially distributed in a non-planar configuration to provide a compact structure adapted to fit to an allocated space or volume of a wireless communication device, such as a portable wireless communication device.

Non-planar metamaterial antenna structures

Wideband and multiband CMOS LNAs

In the digital world, Moore's Law states the number of transistors on Integrated Circuits (ICs) has been doubling every two years since 1965. While these ICs occupy only 10% of the wireless communication device area, the remaining 90%, referred to as RF Front-End Model (FEM), consists of a collection of discrete passive and active components such as antennas, filters, diplexer, duplexers, couplers, power combiner/splitter, and power amplifiers. While these powerful ICs enable effective implementation of Multiple Input Multiple Output (MIMO) digital processing, the main issue of MIMO RF FEM implementation in small devices such as handsets still remains unsolved. Without such a full solution, network providers cannot deploy next generation wireless broadband networks, such as 3GPP Long Term Evolution (LTE) networks, that can sustain tens of Mbps throughput with mobility. This paper addresses this specific problem by presenting an LTE MIMO air interface solution for handsets using metamaterial designs, which offer small, low-cost, and low-profile antennas printed directly on PCB for easy integration and simple manufacturing - all critical factors for rapid deployment and commercial success. The proposed metamaterial MIMO array consists of dual resonance antennas occupying λ 0 /10 × λ 0 /41 × λ 0 /387 volume at center frequency 771MHz of the LTE band 746–796MHz. The performances of two antenna array configurations with spacing of λ 0 /13 and λ 0 /5 are studied while quantifying its near-filed and far-field channel correlation.

Compact metamaterial antenna array for long term evolution (LTE) handset application

The paper presents two examples of compact antenna arrays for MIMO applications which were designed based on MTM technologytrade. These multi-band antenna arrays occupy smaller volume than the conventional antennas while they provide equal or better performances. These antennas in addition to the excellent performance can be easily integrated with any PCB based circuit, thus significantly reducing the cost in the mass production. The compact antenna arrays can enable advanced MIMO solutions like switched arrays and beamforming arrays which can provide diversity gains in addition to MIMO gain.

Compact dual-band planar metamaterial antenna arrays for wireless LAN

We have presented the first metamaterial MIMO antenna array implemented in a commercially available 802.1 In wireless LAN access point. Despite the extremely small size of the metamaterial array, its performance equals that of the much larger conventional antenna solution. The metamaterial antenna array utilized existing PCB fabrication technology and was readily integrated into the access point.

A. Gummalla

Papers

Compact dual-band planar metamaterial antenna arrays for wireless LAN

Beyond 3G: Metamaterials application to the air interface