First theoretically investigated by Russian physicist Victor G. Veselago some 40 years ago, left-handed materials (LHMs), in which the real parts of the permittivity and permeability are simultaneously negative, are now generating interest as new research is leading to some novel real-world applications. This is evidenced by the rise in intellectual property associated with these materials.
Due to the absence of these negative index materials (NIMs) in nature, experimental research on these materials did not commence until this past decade. In 1999, John B. Pendry of the Imperial College London theoretically proposed two artificially engineered structures (or meta-materials) consisting of split-ring resonators (SRRs), which exhibit a band of negative permeability, and wires, which provide the negative permittivity at a certain frequency range. However, a group led by Professor David Smith of the University of California San Diego was the first to patent left-handed composite media technology (see U.S. #06791432), and produce the first meta-material prism. It comprised a 2D array of copper strips and SRRs that exhibited a negative index of refraction in a microwave frequency range.
What was once an academic curiosity is now starting to get industry's attention, especially given that NIMs could lead to novel lensing, antennas (see U.S. #06788273; U.S. #06958729), waveguides, and filtering applications. This technology could lead to novel optical device developments with the potential to dramatically improve the performance of existing phased array antennas, optical beam-forming networks, antenna remoting, and transportation of RF power through fiber.
As evidenced by an increase in IP activity since 2001, the LHM patent portfolio has now grown to include three issued patents and 27 patent applications with 50 percent of the IP emanating from academia and the other half from industry. (See Figure 1). In addition to UCSD, other top patent assignees generating LHM-related IP include Raytheon Corporation (Waltham, MA), Olympus Corporation (Tokyo, Japan), New Mexico State University (Las Cruces, NM), Lucent Technologies Inc. (Now Alcatel-Lucent; Paris, France), and the Massachusetts Institute of Technology (Cambridge, MA). The three granted patents associated with LHMs are briefly discussed below.
Figure 1. Patent activity for all LHM-based IP (IP count of LHM issued patents and patent applications by year of publication and organization type). Comprehensive search strategies were devised in Nerac's proprietary Advanced Research Environment (ARE) to extract the relevant IP data from the company's patent index database resources. U.S., select European, and Japanese patent authorities were examined.
Key Granted PatentsU.S. patent #06791432 relates to a left-handed composite media technology (assigned to the University of California at San Diego and granted in 2004). The patent describes a composite media having simultaneous negative effective permittivity and permeability over a common band of frequencies.
Full Patent PDF: U.S. #06791432
U.S. patent #06788273 focuses on radome compensation using matched negative index or refraction materials (assigned to Raytheon Corporation and granted in 2004). Consisting of a negative index inner layer material and a positive index outer layer, this meta-material-compensated radome technology solves the bore sight angle problem with a minimum of complexity by adjusting the thickness and refractive indices of both layers to insure that a beam of light passing through the radome is effectively not refracted.
Full Patent PDF: U.S. #06788273
U.S. patent #06958729 relates to a phased array meta-material antenna system (assigned to Lucent Technologies and granted in 2005). The patent describes an efficient, low-loss, low side lobe, high dynamic range phased-array radar antenna system. It combines the use of manmade negative index of refraction meta-materials to reduce the antenna's side lobes and suspended low loss microstrip transmission lines for reduced signal loss.
Full Patent PDF: U.S. #06958729
Phillip B. Espinasse is a Nerac Patent Analyst. Nerac's Intellectual Property Solutions provide a practical understanding of the IP landscape, helping organizations to make informed decisions about R&D planning and business strategy development. Nerac analysts work with clients in the areas of patentability and invalidity, patent portfolio analysis, commercialization strategy, and white space analysis.