Analytical Model Of A Helmet Mounted Conformal Patch Antenna For An Assortment Of Canical Shapes
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Date
2012
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Department
Electrical and Computer Engineering
Program
Doctor of Engineering
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This item is made available by Morgan State University for personal, educational, and research purposes in accordance with Title 17 of the U.S. Copyright Law. Other uses may require permission from the copyright owner.
Abstract
The space of application of patch antennas has dramatically expended. Mobile and satellite communication, Global positioning system or GPS, radio frequency Identification or RFID, Worldwide Interoperability for Microwave Access or WiMax, Radar, Rectenna application, Telemedicine applications, and Medical applications just to list a few explored fields. One major reason is that, not only you can always adjust the patch elements to achieve the performances characteristic satisfied by most antenna type, you can also dissimulate the patch itself on the body of the structure requiring the antenna. The engineering advantages inhibit the drawbacks especially because a lot optimization method can be developed to correct the setbacks. Although they are many variations of patch antenna, the basic configuration is planar. A flood of research on basic patch antenna design is in the literature. We narrow this dissertation to antennas that follow the curves contours of spherical structures. An Analytical Model of a Helmet-Mounted Conformal Patch Antennas for an Assortment of Canonical Shapes is presented. There are essentially two approaches employed to solve for the internal resonances of patch antennas on spherical geometries. One method is analytic while the other relies on computer simulations. The analytic techniques rely on approximations such as the cavity model for a patch antenna to obtain resonances close to the actual resonances of the antenna. These Eigen-value resonances are good starting points for the more exact computer simulations. As mentioned, the most frequently employed analytic technique used to model resonances of a patch antenna presumes simplifying assumptions. Due to the spherical curvature of the surface of our structures, this approach gives rise to fractional orders of associated Legendre functions. In this presentation, the internal TM field configurations are determined and the methodology for extracting the resonances is reviewed. Spherical geometries can also exploit Schumann's analytic method first used for modeling the natural resonances of the earth's atmosphere presuming the Ionosphere and earth act as perfect electric conductors. Schumann presumed the distance between the earth and the Ionosphere was negligible compared to the radius of the earth. This method can also be applied to patch antennas on spherical geometries and will be discussed. Once approximate resonances are determined, one can then use commercial codes to fine-tune the resonance of the spherical patch antennas. Having constructed and measured the canonical shapes, we will use the analytical results as the starting points for our High Frequency Structure Simulation or HFSS optimizer to simulate the resonances and compare it to the measured data. The frequencies ranges predicted for the spherical patch antennas are indeed captured in the measurement. The study clearly link Schumann analysis of earth-ionosphere's Electromagnetic fields to the analysis of micro strip spherical antennas. The HFSS simulation is in reasonable agreement with the theoretical predictions and measurements. The study of the spherical cap is used as a template for the other canonical geometries.