Design, Development and Optimization Of Microwave Package for Space Communication Payload

Abstract

The purpose of a microwave package is to integrate all the components of a sub-system in such a way to minimize size, mass, complexity and cost. The mechanical package should provide electrical interfaces between the components in the spacecraft system and ensure high reliability, as the package has to withstand space environment. Mechanical design of spacecraft components transforms the electrical design to its functional level by providing robust solutions supported by electrical layout optimization. Light weight and low volume packages have always been a challenge for design. Completing the design with a desired functional performance in multidisciplinary environment is a herculean task. This dissertation dwells into similar challenge doing design and development of Communication payloads proposed by ISRO in the GEOSAT communication payload mission. The work focuses on conceptual design, development and optimization of Ku Band Driver Amplifier subsystem using the state of the art CAD based FEM techniques. In present dissertation work, design synthesis for selecting package configuration and geometrical tolerance has been made. The principles of Design for Manufacturing (DFM) and Design for Assembly (DFA) are implemented during design, development and manufacturing of the package. The entire subsystem with machining and assembly aspects has been simulated using 3D CAD model. The detailed model includes all microwave carrier plates, PCBs with input and output devices, totaling more than 60 sub parts. After making various layouts and changing topology, reduction in foot print area and weight has been achieved up to 30% and 37% respectively. The 3D CAD model and FE model have been developed to determine natural frequency of existing package. The CAD based optimization resulted in to 28 % reduction in total mass. To validate the FE analytical results, the unit has been fabricated from space qualified material using precision milling machine. The unit has been assembled as per actual spacecraft condition with use of dummy mass. The vibration test has been carried out on this assembly. The experimental results have justified the FE analysis approach for design and optimization. This dissertation work sets guidelines for future package design and optimization for same kind of subsystem.