ORCID
0009-0003-0316-7244
Date of Award
2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Electrical Engineering
First Advisor
Jeff Frolik
Abstract
Soil moisture measurements are important environmental parameters for hydrologicalmodeling, optimizing agricultural irrigation, and predicting soil behaviors, including catastrophic events such as landslides. In many of these applications, soil monitoring over wide geographic areas is desirable to make informed decisions and build accurate models. However, high costs associated with traditional wired moisture probes limit the feasibility of large-scale deployments. Passive wireless sensors provide a potential affordable alternative to wired probes. Such passive devices do not require internal power sources but are excited when interrogated with a wireless signal and transmit a response. Harmonic transponders are one such class of passive device that respond at the second harmonic, 2f , when interrogated at some fundamental frequency f .
This thesis explores harmonic transponders as the basis for a soil moisture monitoringsystem, wherein many transponders are deployed over a large area and periodically measured by an interrogator to determine soil moisture. An interrogation method for determining the attenuation in the wireless link to the harmonic transponder from the device’s response is tested against soil moisture content and a method for locating and tracking deployed harmonic transponders based on monopulse direction finding is developed. Both the locator and interrogator are implemented on software defined radio, as a portable and cost-effective platform suitable for use in the field.
Language
en
Number of Pages
108 p.
Recommended Citation
Fought, Samuel, "Locator-Interrogator for Embedded Harmonic Transponders" (2024). Graduate College Dissertations and Theses. 2010.
https://scholarworks.uvm.edu/graddis/2010