Surface acoustic wave (SAW) devices have provided solutions to many sensor applications. With the increasing use of the electromagnetic spectrum, the adoption of higher frequencies for new developments is becoming a necessity. SAW devices represent a solution for advancing many emerging sensor's needs given their inherent advantages such as: wireless operation, low cost, and ease of fabrication. However, the SAW technology has been typically limited to frequencies under 3 GHz due to size limitations, increased SAW losses, and the need of an interrogation system suitable for reading SAW sensors at higher frequencies. This dissertation presents the work done to push up the frequency limitations of SAW sensors by using the harmonic response of a SAW device to sense temperature and strain at 4.74 GHz. Transducer configurations for harmonic response are studied using the theory on SAW transduction. The development of 4.3 GHz harmonically operated SAW devices is presented as initial work and part of a NASA SBIR project to investigate the feasibility of the harmonic operation concept applied to the Wireless Avionics Intra-Communications (WAIC) band. Measurements of the devices at fundamental and harmonic frequencies were validated using the coupling of modes (COM) model. 4.74 GHz SAW devices were fabricated using a SAW mask provided by Pegasense, LLC. This mask, designed for 4.3 GHz devices using LN YZ cut, was used to fabricate higher frequency devices using LN YX 128 cut. Temperature and strain SAW sensors harmonically operated at 4.74 GHz were fabricated. Finally, a 4.74 GHz SAW interrogation system is developed, the UCF SAW SDR software is improved, a transceiver is fabricated, and the interrogation of 4.74 GHz harmonically operated SAW temperature and strain sensors is demonstrated.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Electrical and Computer Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Morales Otero, Michael, "4.74 GHz Harmonically Operated SAW Device for Sensing Applications and Interrogation System" (2022). Electronic Theses and Dissertations, 2020-. 1417.