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X-Band 25kW High Power Harmonic Reject Filter

In the year 2015 MIRAD has been requested by ESA for the development of a special harrmonic reject filter to be implemented in their 25 kW X-band high power amplifiers (HPA) delivered by Rheinmetall Italy S.p.A. and installed in their deep space antennas in Cebreros and Malrgüe. At that time there was no supplier in Europ on high power harmonic reject filters. Since MIRAD has been know at ESA for its waveguide filter expertise, this request came to our desk.

The filter is used to suppress the harmonic output frequency response of the HPA by more than 60 dB to ensure that these harmonic spurious signals do not interfere with signal transmission and do not affect or degrade the overall performance of the antenna.

After the successful testing, MIRAD delivered two units of this special harmonic reject filter to its customer in 2016, who integrated them into its HPAs and implemented them in ESAs deep space network. Since then, these filter units have helped to ensure the communication between Earth and several deep space missions. In 2021 Rheinmetall requested again one device that had been manufacrured and delivered in summer 2022.

Key technical challenges:

  • Power handling of 25kW
  • Thermal design of the high power device
  • Avoidance of corona brakdown (arcing)
  • Compact design by ennvelop requirements 
  • Minimization of Insertion losses
  • Mode spike free design
Key functionalities:
  • X-band signal transmission (Tx: 7.145 – 7.235 GHz)
  • Harmonic suppression >60 dB at 14.290 to 14.470 GHz and 21.435 to 21.705 GHz
  • Insertion Loss <0.05dB (Spec.: <0.2 dB)
  • Return Loss >28 dB (Spec.: >26.8 dB)
  • Water cooled

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