Design of COTS Dual-Circularly Polarized Conical-Scan Cassegrain Antenna for Rocket Trackin

Abstract

The purpose of this project is to design a Dual- Circularly-Polarized Cassegrain Antenna used for tracking of DTI’s experimental rocket. Conical-scan tracking scheme is used for simplicity of the design and development instead of electronic scanning. Dual polarizations, LHCP and RHCP, have been used to tackle the change of polarization during the approach of the rocket to the ground station and the departure away from it. As a low-cost prototype, main structure of the antenna consists mainly of a COTS parabolic dish, a CNC-machined hyperbolic subreflector and an FR-4 based dual-circularly polarized Microstrip patch feeder. Various dimensions are optimized to reduce blocking ratio to best suit small parabolic dish as well as to achieve optimal beam shape. One RF channel has been dedicated for tracking purposes in order to maximize the scanning rate while the other is solely used for data reception. Tracking rate and accuracy are designed to match with speed of the rocket acquired from the study of Concept of the Operation (CONOP).