A Flexible Down-Converter for Satellite Communication in the Ka-Band

Abstract

Abstract Conventional communications satellites operate with fixed frequency, polarisation and coverage plans that are drawn up years before their launch during the payload definition phase. The satellite will typically be designed for a lifetime of more than fifteen years. During this operating period, changes in bandwidth requirements and the distribution of the service across its geographic coverage are more than likely. A new generation of communication satellites is expected to respond flexibly to these regional and temporal fluctuations in demand. The concept of cellular division of the coverage area and the coverage of these cells with spot beams in connection with the reuse of frequency bands enables this flexibility. The satellite's frequency plan has to be redefined throughout the mission lifetime via commands from the ground. The Flexible Down-Converter DOCON is one of the new components that allow satellite signals to be redistributed between service areas to flexibly reallocate the most critical spectrum resources as needed. DOCON is a flexible Ka-band down-converter from RF = 27.5 ... 30.0 GHz to IF = 17.7 ... 20.2 GHz designed for GEO communication satellites. The device includes the housing, DC-, RF-, and telemetry / tele-command interfaces. An Engineering Model (EM) in form, fit and function was successfully built and tested. The next stage, the Engineering Qualification Model (EQM), is currently in fabrication and will be qualified until end of 2019. The modular concept comprises hermetically sealed LTCC microwave modules as key building blocks. There are three of these LTCC-modules: the Local Oscillator Module (LOM), the Mixer Module (MXM), and the Variable Gain Module (VGM). Their function and realization shall be discussed in this paper.