Design status of the ACES microwave link

The ACES microwave link (MWL) is a cross-link microwave signal transfer system consisting of a flight segment, which shall be installed on the ACES payload aboard the International Space Station (ISS), and dedicated ground terminals. These ground terminals are intended to be installed world-wide at major time and frequency (T&F) laboratories participating in the ACES experiment programme. The system will allow to compare the phase stability of the master clock signal generated by the ACES space clocks (PHARAO and SHM) with the most precise frequency standards on ground, operated e.g. at LPTF, NIST, PTB with unprecedented accuracy. The ACES MWL project successfully concluded phase CO (preliminary design review) and is presently in phase Cl/D. The paper will report on the current status of design and performance results of the electronics breadboards.