| In this dissertation, several new millimeter-wave phased array circuits and antennas are presented for polarimetric radar applications. In particular, a compact tray architecture is discussed, which is based on new miniature dielectric filled L-shaped horn antennas and Rotman lens beamforming circuitry. The antenna array and associated waveguide feeds are realized through a multilayer stereolighography process, which interfaces with the Rotman lens circuitry through low-profile substrate integrated waveguide to microstrip transitions. The L-shaped horn antenna array is dual polarized, therefore allowing for the independent beam steering of the vertical and horizontal polarizations.; In this dissertation, the Rotman lens is used to achieve broadband true time delay beam steering. In particular, the design of a new low loss Rotman lens is described, where a synthesized dielectric gradient is introduced within the lens to achieve enhanced focusing. Here, the fundamental Rotman lens equations are modified according to geometric optics. With this modified design, minimal power is lost to the side ports of the modified lens, in contrast to the conventional Rotman lenses. This technique allows for an insertion loss improvement of up to 3 dB for the Rotman lens. In addition, further loss improvement is realized due to the elimination of meander lines between the Rotman lens array ports and the antennas. Finally, to improve the angular resolution, a monopulse Rotman lens is described, where 0°/180° switched line phase shifters are integrated with the Rotman lens meander lines.; To demonstrate the feasibility of the aforementioned phased array circuits and antennas, a phased array radar with electronically controlled scanning in the azimuth and elevation planes is implemented. Through observing the signal return from 34 to 40 GHz, the locations of targets are detected within a three-dimensional space with better than 5 cm range resolution.; Finally, by using the same technique that was used for the integration of the Rotman lens circuitry with the horn antenna array, a packaging technique with improved isolation for microwave and millimeter-wave circuits is implemented. Compared to the conventional packaging techniques, the technique presented here shows approximately 20 dB isolation improvement.*; *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Adobe Acrobat. |
