Vertically interconnected wide-bandwidth monolithic planar antennas for three-dimensional-IC

For the last two decades, planar monolithic microwave integrated circuit (MMIC) has reached its limitations and can no longer address the needs of the next generation microwave communication systems. The three-dimensional monolithic microwave integrated circuit concept (3D-MMIC) is the key to reduce the volume, weight and cost of the next generation microwave IC while still maintaining high level of performance and functionality. Applying 3D-MMIC technology to a phased array antenna system yields a novel multilayer monolith T/R module in which active devices and the planar antenna together with their associated networks are monolithically processed, vertically stacked and combined on a single chip within a small volume. The goal of this research is devoted to the development and implementation of a novel wide bandwidth planar antenna configuration using new concepts provided by the 3D-MMIC technology.; The major challenges lie in the design of efficient antenna structures on very thin substrates with closely spaced bottom ground planes. The two-arm narrow-slotted Archimedean spiral antenna was chosen as the final configuration due to its broadband radiation characteristics and less dependency on substrate thickness. With the slot width being comparable to the substrate thickness, efficient radiations were achieved from the spiral antennas with substrates that were 0.073lambdag, 0.0056lambdag, and 0.0038lambdag thick. Both computational and experimental results have shown that narrow slot design is the key to increased bandwidth and efficiency of the thin substrate slot antenna. And only the Archimedean spiral design can keep the slot at a constant width while taking advantage of the frequency-independent characteristic of the spiral antenna. Furthermore, in order to feed the two-arm spiral antenna, a wide bandwidth balun circuit compatible with 3D-IC configuration was also developed. As a demonstration of the next generation phased array antenna systems using 3D-MMIC T/R module, a 4-element linear antenna array was assembled using the monolithically processed Archimedean spiral antennas and loaded-line phase shifter. Also, a unique fabrication procedure has been developed to implement the vertically interconnected Archimedean slotted spiral antenna and the feeding balun circuit.