Abstract

Millimeter-waves are of particular interest because they act as the only part of the terrestrial blackbody emission spectrum that transmits well through atmospheric obstructions such as fog and smoke. Inherently, millimeter-waves possess the ability to penetrate thin dielectrics such as clothing, which can be used at security checkpoints to determine if a person is concealing any type of weapons, explosives, or any other harmful objects. Due to the lack of sufficient detectors and sources, extensive research of millimeter-waves and their applications to imaging systems has not been carried out.

In this thesis, I present two new antennas for use in an imaging array. Both structures will use a stacked patch configuration to expand bandwidth and a waveguide-to-horn transition to increase the gain and create a narrow beamwidth. The main difference between the antenna designs is the feed structure. This results from the difficulty to scale down microwave designs to millimeter-wave frequencies. At K-band, an aperture-coupled feed allows design flexibility while at W-band, a coplanar waveguide feed creates a planar configuration. Experimental results will show the possibility of creating an antenna at W-band for use in a millimeter-wave imaging system.