Collaborative Research: Arrays, Analog RF 2-D Filters, and Nanostructured Multiferroic Antennas for MM-wave OAM-Multiplexed Wireless Systems

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Wireless radio frequency (RF) communication has relied on encoding information in the amplitudes and phases of waves that have patterns analogous to the concentric circular ripples produced by dropping a stone into a pond. Radio waves that are said to carry non-zero Orbital Angular Momentum (OAM) are more like the swirling vortices that develop as water drains from a sink. The OAM property of these vortex waves provides an additional dimension for transmitting information. This research will investigate antenna array analog filtering methods that can extract the OAM information from a received signal despite the presence of electromagnetic interference and noise. Mathematical filter design techniques, founded on topology and multi-dimensional signal processing, will be realized using complementary metal oxide semiconductor (CMOS) based recursive filters, which will enable high-frequency, continuous-time data extraction. Circuit theory will be created for use in designing RF vortex wave array processors that have multi-GHz bandwidth for challenging realizations in the microwave and millimeter-wave range. This work provides a new technique for exploiting an unused design dimension. Apart from providing communications engineers with a new means of physically realizing OAM-multiplexing, the results of this effort might offer paradigm-changing solutions for improving imaging and encryption technologies. Such technologies could impact medical, telecommunications, and defense industries as well as radio astronomy and atmospheric science. This knowledge will be distributed through outreach activitie at conferences and meetings. The project includes a female PI and will involve participation from underrepresented groups. There will be summer STEM workshops for high-school girls at both the University of Akron and the University of Texas at Dallas. Lab open houses will educate the public of the possible merits of this project for future wireless systems.Vortex modes are orthogonal to each other despite occupying the same carrier frequency and bandwidth, allowing independent encoding of information. OAM-multiplexing allows encoding with overlapped radio bandwidth. The project explores array-processing schemes for electronically tuning onto desired vortex modes using array processing and analog RF integrated circuits (ICs). Filter design techniques founded on curvilinear multi-dimensional signal processing are proposed for vortex-wave array processing using recursive filters, leading to high frequency continuous-time RF CMOS realizations. Circuit theory will be created for use in designing RF vortex wave array processors that have multi-GHz bandwidth for challenging realizations in the microwave and millimeter-wave range. Design methodologies and techniques for analog realizations will result from theoretical analysis, circuit synthesis, simulation and modeling of the vortex signal processors. To circumvent the problem of scattering of incoming signals, the project explores novel subwavelength antennas that minimize radio wave reflections by virtue of their smallness and the fact that the characteristic impedance of the antenna material will be engineered so as to achieve impedance matching with free space. This work will take advantage of the cross-coupled electric, magnetic and acoustic properties of magnetoelectric multiferroic materials (to be realized using polymer nanocomposites) to drastically enhance the performance of electrically small antennas. Conversion between electromagnetic and acoustic energy is advantageous because a signal of a particular frequency will have a much shorter acoustic wavelength than that of a radio wave.