NSF Award
2402114
A groundbreaking broadband probe-based RF and microwave measurement system is introduced, representing a significant advancement in electromagnetic measurement technology. The proposed RF probe acts as point transmitter and has a very small form factor (cross section area less than one square millimeter) fed by an optical fiber and thus is electromagnetically non-invasive. This pioneering technology enables the comprehensive assessment of the electromagnetic response of any receiving system to highly localized applied electric fields, marking the inaugural demonstration of a method capable of experimentally measuring the electromagnetic Green's function of receiver systems. The ability to experimentally measure a system's Green's function would represent a fundamental shift in electromagnetic measurements and characterization, unlocking a multitude of possibilities that were previously cumbersome or unattainable. The proposed probe heralds a new era of experimentation, facilitating endeavors such as: i) Precision measurement of antennas' receiving radiation patterns under any arbitrary incident field, whether in the near- or far-field regions; ii) Identification and localization of manufacturing defects and malfunctioning elements within extensive phased arrays and massive multiple-input multiple-output (MIMO) communication systems, streamlining diagnostics and maintenance; iii) Thorough characterization of electromagnetic interference and compatibility (EMI/EMC) in microwave and millimeter-wave integrated circuits (MMICs) and systems-on-chip (SOCs) with micron-level resolution, enhancing overall system reliability and performance; and iv) Investigation into the effects of RF and microwave radiation on biological tissues, offering high selectivity for applications such as cancer treatment, RF ablation, microwave hyperthermia, and RF dosimetry, thereby advancing medical science and therapy techniques. These examples underscore the broad spectrum of applications and the transformative potential of the proposed probe technology, paving the way for unprecedented advancements in electromagnetic research, engineering, and healthcare.<br/><br/>By strategically maneuvering the localized transmitting probe across the target receiving system and recording receiver output at each excitation point, the system's response to any desired applied electric field can be fully characterized. Comprising three integral subsystems, the proposed measurement probe encompasses an optical modulator and optical fiber to convert the applied RF signal into an intensity-modulated laser light source. At the probe's tip, a series of photo-voltaic cells generate a high reverse bias voltage when illuminated by the optical signal, while an RF avalanche photodiode, also housed within the tip, demodulates the optical signal under the reverse bias from the photovoltaic cells. This process generates a highly localized, robust RF electric field across a miniaturized metallic dipole. Fabricated on a standard 65-nm bulk CMOS process, the probe confines the electric field to an area of 100 µm × 100 µm, achieving field intensities on the order of 10 kV/m. Remarkably versatile, a single probe is capable of measuring system responses from zero to 12 GHz with arbitrary polarization, enhancing its utility across a spectrum of applications.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
