Cooling System for a Ka Band Transmit Antenna Array

Abstract

Active antenna arrays working at higher frequencies result in higher packaging densities. The antenna array under consideration operates at about 30 GHz and will be installed in an aircraft. Commercially available power amplifiers at these frequencies have an efficiency of typically 20 %, which results in high amounts of dissipated heat for the required high radiated power. The dissipated power, up to 9.5 kW as a worst case for a 50 × 50 element array, has to be transfered from the antenna to a heat exchanger or to the ambient air. Several cooling techniques including forced air and liquid cooling as well as heat pipes will be presented in this work, always considering the packaging density and the little space available. Simulations based on the software Flotherm led to the result that a liquid cooled cold plate is the most feasible approach while meeting all requirements. Experiments on a simplified model and comparison with simulations confirmed the results. Additionally, a forced air convection fin heat sink based on standard components was proposed, which can be used for an antenna demonstration model with 4 × 4 elements.