Electrical and Computer Engineering ETDs

Publication Date

Spring 4-2-2021

Abstract

Foliage penetration (FOPEN) radar at lower frequencies (UHF, VHF) is a well-studied area with a wide set of contributions. However, there is growing interest in using higher Ku-band frequencies (12-18 GHz frequency range) for FOPEN. In particular, the reduced wavelength sizes (centimeters range) provide some key saliencies for developing more optimized foliage detection solutions. The disadvantage is that exploiting Ku-band for FOPEN is complicated because higher frequencies have much more pronounced scattering effects due to their smaller wavelengths. Despite these challenges, certain foliage characteristics and signal parameters can help improve electromagnetic (EM) wave penetration in the Ku-band such as foliage type, incident angle, polarization, etc. Moderate foliage with lower density can also provide more “holes” for higher frequency EM waves to pass through. As a result, there is significant interest and valid opportunity to study FOPEN in the Ku-band.

In this dissertation, a methodology is laid out for modeling and simulating FOPEN problems in the Ku-band. Unprecedented comprehensive computer-aided design (CAD) tree models were specifically designed to be implemented for characterizing the phenomenology of Ku-band EM wave transmissions through moderate foliage. The detail obtained in these trees is unique in FOPEN modeling because many studies in this area focus on lower frequencies where precise tree parameters are not required due to the associated large wavelengths relative to the tree dimensions. However, it is necessary to model explicit tree structures in the Ku-band range where the wavelength is notably smaller and the details of the trees have more of an influence on EM waves (i.e. perturbation, scattering, attenuating, reflecting, diffracting etc.). Moderate foliage is of most interest because with less dense foliage there is a higher percentage of Ku-band transmission. The EM wave and foliage interactions are simulated with the computational electromagnetics (CEM) Altair FEKO software. The realistic tree models implemented for simulations are created in the CAD software Arbaro and pre-processed with the Altair HyperMesh software. The impulse response (IPR) and electric field results are post-processed in MATLAB.

Keywords

Computational Electromagnetics, CEM, Foliage Penetration, FOPEN, FEKO, Hypermesh, Altair, Ku-band, Synthetic Aperture Radar, SAR

Sponsors

Sandia National Laboratories (SNL) and General Atomics Aeronautical Systems, Inc. (GA-ASI)

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Dr. Christos Christodoulou

Second Committee Member

Dr. Armin Doerry

Third Committee Member

Dr. Mark Gilmore

Third Advisor

Dr. Nasir Ghani

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