Date of Award

Fall 1997

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Electrical and Computer Engineering

First Advisor

Richie, James

Second Advisor

Ishii, Thomas K.

Third Advisor

Strangeway, Robert A.


An antenna that is used on a platform where the wavelength is on the order of the airframe dimensions can sometimes give unpredictable results. If the wavelength is much less than the dimensions of the platform, then the platform usually can be considered as a ground plane. Although image theory is only strictly valid for an infinite ground plane, in this example image theory could be used as a good engineering approximation for the antenna on the platform (being the ground plane). The differences between the theoretical (using the image theory approximation) and actual results should be small in most cases. If the wavelength is much larger than the dimensions of the platform, then it should be possible to model the platform and/or antennas using a multi-pole expansion. The next logical question is, "How do you model a platform when the wavelength is on the order of the dimensions of the platform?" Commonly, numerical techniques are used to solve for the desired electromagnetic properties. But if it is desired to enhance the characteristics of a transmission/reception platform with different antennas or locations, it would have to be simulated or physically tested every time. A method of moments computer code is used in this thesis to simulate a specific platform in order to find various electromagnetic characteristics of that platform. The characteristics would allow for a better understanding of how to enhance a transmission/reception platform without having to simulate the antenna/platform configuration for every possible combination of configurations. Although the characteristics would be developed with a specific platform in mind, the characteristics could be applied to various platforms where the platform dimensions are on the order of the wavelength. The characteristics learned at 40 MHz, 60 MHz, and 80 MHz were compiled to form a set of guidelines. These guidelines focused on antenna types and antenna locations on a platform where the platform dimensions are on the order of the wavelength. The guidelines were applied to the airframe at the various frequencies to come up with antenna types and locations that would satisfy a given set of desired radiation pattern characteristics. A desirable radiation pattern, over the given frequency band, was obtained by locating three sets of loop antennas on the airframe.



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