Creeping Wave Propagation On Cylindrical Radiating Structures

Abstract

Weather radar is a powerful tool for detecting hazardous weather that may impact the lives of many. Most weather radars used by meteorologists today rely on a mechanical sweep to obtain volumetric data. This mechanical sweep takes at minimum, four minutes to complete a full scan and there is not great flexibility in the scanning pattern. Phased array radars have been introduced as part of a multipurpose plan to replace current weather radars. Phased array radars allow scanning flexibility with fast scanning capability, such as electronic beam steering. When planar phased array radars are made to be polarimetric, which is necessary for accurate weather detection and prediction, bias errors occur that corrupt the data. In order to have the flexibility and swift updates of a planar phased array radar without the bias errors, a cylindrical phased array radar was created. Cylindrical phased array radars have the unique challenge of a type of surface wave, called a creeping wave, that causes back radiation levels to be destructive to pattern quality. Energy from broadside of the radar is azimuthally carried towards the opposite side. This challenge has not been greatly explored due to cylindrical phased arrays being on the leading edge of radar technology. This thesis seeks to explain, address, and mitigate front-to-back pattern isolation level problems that prevent the radar from reaching its meteorological potential. The two methods used in this thesis to intensify ways to reduce back radiation levels are called phase mode elimination and alternating projections.