Design of a new smaller lighter faraday rotator for ACERAD radar QOTL

We describe a new Faraday rotator as part of the Quasi Optical Transmission Line (QOTL) on the Aerosol/Cloud/Ecosystems (ACE) mission. A QOTL design has been completed and laboratory tested and is the subject of a separate paper. A major component of the QOTL is a Faraday Rotator used in the simultaneous transmit and receive operation. It rotates the polarization of the transmitted and received signals by 45 degrees in opposite directions, thus creating a 90 degree polarization difference which is utilized by a linear polarizer to separate the two. This paper describes the design of a new rotator which is substantially lighter and smaller than a previous one used in the CloudSat radar jointly developed by JPL/NASA, Canadian Space Agency and other agencies. This is achieved by using better ferrite materials and a higher degree of optimization in the design. The weight and volume of the rotator have been substantially reduced to less than one third of the original. Furthermore, the RF performance of the new magnet design is much better than original design in the 94 GHz range. The new Faraday Rotator has been fabricated and tested with very good results.