Date of Award

2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

Committee Chair

Z. A. Pour

Committee Member

Junpeng Guo

Committee Member

Robert Lindquist

Subject(s)

Microstrip antennas., Electromagnetism.

Abstract

Microstrip patch antennas are light weight and low cost antennas that are generally made of perfect electric conducting (PEC) materials and excite the transverse magnetic (TM) modes, when supported by a thin dielectric slab. In this thesis, a new type of patch antennas is investigated to excite the transverse electric (TE) modes, based on electromagnetic duality theorem. To this end, new sets of boundary conditions are enforced through utilizing perfect magnetic conductors (PMC) instead of PEC. That is, the zero-impedance PECs are replaced with high-impedance PMCs. Since a PMC does not exist in nature, artificial magnetic conductors (AMC), based on unipolar compact photonic bandgap (UC-PBG) unit cells, are employed both in the patch and the ground plane to excite the TE modes in microstrip patch antennas. The UC-PBG unit cells are high impedance surfaces that mimic the properties of perfect magnetic conductors. The impedance and radiation properties of this antenna are compared to those of a conventional microstrip patch antenna that excites the dominant TM mode. Different ground plane sizes are investigated and compared for both PEC and PMC antennas. In order to overcome the narrowband characteristic observed in microstrip patch antennas, conformal wideband PEC antennas with a U-slot are studied and designed. Based on this idea, a new wideband antenna that excites the dominant TE mode is investigated. It is found that the AMC microstrip patch antennas are smaller in size compared to the conventional PEC patch antennas. They also suppress the unwanted surface waves, which cause spurious radiation, and thus provide electrical isolation from the surrounding circuits. The latter is quite beneficial in phased array antennas to reduce mutual couplings between neighboring elements. Therefore, the PMC patch antennas may outperform their PEC counterparts in applications, where size, surface waves, and isolation are of primary concern.

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