The PI requests NSF funding for the proposed collaborative research between the Hawaii Center for Advanced Communication at the University of Hawaii at Manoa, and the Trex Enterprises Corporation in the island of Kauai, Hawaii. The proposed project involves fundamental research, innovative design, fabrication, and testing of a unique approach for developing high performance tunable RF devices and phased antenna arrays.
Specifically, he proposes to use novel multilayer dielectric materials to design tunable RF devices such as phase shifters and filters, and integrate these multi-dielectric designs with the Continuous Transverse Stubs (CTS) technology to develop high performance, low cost phased antenna arrays with beam steering capabilities. The multilayer dielectric designs involve a thin layer of a Ferroelectric material (e.g. BSTO) sandwiched between two layers of lossless or low loss (SiO2) materials. The separation of the coplanar conductors and the Ferroelectric material using a thin (0.5um) resulted in overcoming a long standing problem that was often encountered when using the Ferroelectric material technology. It significantly reduces the insertion losses while maintaining a significant fraction of the other expected high system performance parameters such as tunability. Preliminary simulation results in both the phase shifters design and the CTS phased antenna array areas showed that this proposed multilayer dielectric arrangements provides significant advantages including reducing the often unacceptably high insertion losses, improving the impedance matching characteristics, and providing practical values of figures of merits such as phase shift per dB (over 30o/dB using coplanar waveguides at 10GHz), and beam steering capabilities (-35o to +35 o with 20% Ferroelectric material tunability) for the CTS antenna array case.
The insertion of the low loss dielectric layer between the coplanar conductors and the Ferroelectric material, however, created new and in a way significant design, simulation, and implementation challenges. In the simulation area, for example, it is computationally very difficult to simulate complete structure that includes electrically very thin layers of high dielectric materials. Equally challenging, is to design an effective DC biasing mechanism now that the Ferroelectric layer is separated from the coplanar conductors. Impeding biasing conductors on the surface or within the Ferroelectric material may be possible but concerns regarding material compatibility, and the possible RF shielding and interference need to be carefully addressed. It is the objective of the proposed work to address these challenges together with our partner Trex Enterprises who will provide the technical competence, expertise, and the State-of-the-art experimental facilities for carrying out the material testing and the fabrication responsibilities. It is believed that the proposed approach will, at the long last, provide a successful design of high performance RF devices using the much anticipated benefits, but difficult to realize, Ferroelectric material technology. Significant amount of detailed research and fundamental understanding, however, are still needed but initial simulation results are very encouraging and the payoff is expected to be very significant.
Intellectual Impact: Tunable RF devices and phased array antennas present critically important technologies for broad range of applications in wireless communication, radar, space exploration, and remote sensing. The proposed novel approach that is based on the use of multi-dielectric layers including a thin film Ferroelectric material is new and is expected to produce high performance devices and systems. This presents a paradigm shift that may ultimately realize the much anticipated benefits from the Ferroelectric material technology and its RF applications. The collaborative effort between the University of Hawaii and Trex Enterprises provides integrated analytical and engineering design effort that will lead to the fabrication and the ultimate testing of successful prototypes. Education component includes one PhD graduate dissertations, a research associate, and undergraduate students who will work on dielectric measurements and the Ferroelectric material processing.
Broader Impact: Much is expected from the successful completion of this project. On the technical side, fundamental research in both the RF and ferroelectric material technology will be conducted and will help boost understanding of avenues to effectively realization the much anticipated benefits from this technology. On the intellectual property side, new high performance and low cost tunable devices and antenna arrays will be developed with broad commercial and military applications.
