Radiation characteristics of cylindrical microstrip arrays

For microstrip arrays mounted on a cylindrical surface, several related studies have been reported, and most of the work emphasizes the design and characterization of N-element wraparound arrays (1/spl times/N arrays) for omnidirectional radiation in the roll plane of the cylindrical host. Such studies include linearly polarized and circularly polarized wraparound arrays, and they can find applications ranging from radio guidance of missiles to mobile-phone base stations. And owing to structural reasons, many N/spl times/N microstrip arrays must be mounted on curved (mainly cylindrical) surfaces. It has been demonstrated previously that introducing an excitation phase difference between columns of the array through the design of the feed network can compensate the curvature effects on the propagation path difference between the columns of a cylindrical microstrip array. The curvature effects on the radiation patterns of a cylindrical microstrip array, however, are not characterized. We present a full-wave analysis of the radiation patterns of an N/spl times/N cylindrical microstrip array. Theoretical formulation for the radiation patterns of the cylindrical microstrip array is described in detail, and a specific case for a cylindrical microstrip array operated in the Ku-band is studied. Curvature effects on the radiation pattern and side lobe level (SLL) for the array mounted on ground cylinders with various radii are calculated and analyzed. Experiments for the cylindrical microstrip array were also conducted, and measured radiation patterns are shown for comparison.