Investigation of a New Class of Low-Profile Multi-Layer Printed Antennas

摘要

The annual reports, previously submitted to the ONR in 1998, 1999 and 2000, have detailed most of our research work on this project. The present report only covers the progress made during the October 2000 - September 2001 interim period. We have made progress in the following area: (1) The previously developed multi-layered gain enhancement technique for printed antennas has been extended to design of proximity-fed and aperture-fed antennas for millimeter- wave applications. Design optimization for the case of a four-layer proximity- coupled patch at a frequency of 31 GHz is presented and its performance in terms of gain, pattern and surface wave efficiency is analyzed. It is shown that conductor losses using this gain enhancement technique, is significantly less than that in a standard microstrip array with a similar gain. The mutual coupling and surface-wave effects in a linear array of such radiating structures are also studied. In addition, an alternative high gain technique, based on the Yagi-like concept that utilizes parasitic elements at the interface between layers has also been investigated in detail for millimeter-wave applications. (2) Effect of curvature on gain enhancement of a multi-layered microstrip antenna is investigated by analyzing the radiated fields of a patch in a multi- layered cylindrical surface. It is shown that curvature effect could significantly change the maximum gain conditions previously reported in the literature for a planar multi-layered microstrip antenna. Development of a FDTD code for accurate characterization of the gain-enhanced printed antennas on a cylindrical surface, is presently in progress.