Analysis and design of integrated-circuit horn antennas for millimeter and submillimeter wave applications.

Abstract

Millimeter and submillimeter-wave systems find applications in remote-sensing, radio-astronomy, satellite-communications, collision avoidance, radars, imaging and tracking through rain and fog, and plasma-diagnostics. Traditionally the antennas which are used at submillimeter-wave frequencies are the machined corrugated and dual-mode horn antennas. However, these antennas are hard to manufacture at sub-millimeter wavelengths. In this work, the integrated-circuit horn antenna is considered as an alternative to the machined horn antennas. The integrated-circuit horn antenna is analyzed and optimized so that it becomes competitive with the best machined horn antennas. This is important because it enables the implementation of inexpensive integrated-circuit receivers, allowing an entire spectrum of scientific and commercial applications which are currently considered too bulky and expensive to be undertaken (landing systems, radio-astronomical imaging, mobile-communications). The integrated horn antenna consists of stacked silicon wafers which are anisotropically etched to form a pyramidal cavity. The cavity is excited by a strip-dipole suspended on a thin dielectric membrane. For the design of the integrated horn antenna, a full-wave analysis has been developed and verified experimentally. The analysis is based on the integral equation method and the pertinent Green's function is obtained using the mode matching technique. The input impedance of the feeding strip-dipole is accurately predicted, enabling the efficient hybrid integration of SIS and Schottky-diode detectors. The rigorous analysis has also been extended for integrated horn arrays by combining it with Floquet mode theory in the transmitting mode. To optimize the integrated horn antennas, the full-wave analysis has been utilized to overcome the low-gain limitation stemming from the 70$\sp\circ$ flare angle, which is inherent in the anisotropic etching of silicon. For this purpose, a new diagonal step-profiled integrated horn has been introduced with high gain and symmetric radiation patterns. Also a novel multimode quasi-integrated horn antenna has been investigated, for which a systematic design methodology has been developed. The quasi-integrated horn antenna is competitive to the best machined horn antennas. Finally membrane-free integrated horn antennas have been proposed and analyzed rigorously. Their advantage is that the processing electronics can be monolithically integrated directly with the strip-dipole.