Engineering Expertise for Space CommunicationsUltra‐low noise amplifiers are necessary for satellite missions where link margins are critical, for example for Deep Space Missions. The use of cryogenically cooled LNAs can provide improved ground station G/T at a fraction of the cost of increasing the antenna diameter.
Callisto has developed cryogenic low noise amplifiers in S‐, X‐ and Ka‐bands for the European Space Agency ground station network.
Our designs use HEMT microwave devices, which are well suited for cryogenic operation.
The LNA systems use a 2‐stage Helium closed cycle refrigerators, which maintains the HEMT amplifier at a temperature of 15 Kelvin inside a vacuum Dewar. The refrigerator is designed for continuous operation with service intervals of more than one year.
Cryo‐LNA Specifications
| Parameter | Specifications | ||
| Frequency Band | S‐Band (2.2‐2.3GHz) |
X‐Band (8.4‐8.5GHz) |
Ka‐Band (31.8‐32.3GHz) |
| Noise Temperature | 10K | 11K | 30K |
| Gain | > 55dB | ||
| Input VSWR | > 1.4:1 | ||
| Base temperature | 15K | ||
| Cooldown Time | 5hrs | ||
| Warmup Time | 2hrs | ||
| Service Interval | 13 000hrs | ||
Cryogenic LNA View
An improved maintenance concept is implemented on new cryogenic LNAs. This concept uses a sleeve system which enables the User to replace the refrigerator without opening the sealed enclosure. The main advantage of this concept is to drastically reduce the down‐time of the operational system (typically from 36 hours to 12 hours) and to avoid the need of having a specialist cryogenic technician on‐site for services or repairs. The sleeve design means that first level maintenance actions can be carried out by the End User’s own maintenance staff after a Callisto training course. The replaced refrigerator unit is simply shipped back to the factory for service or repair.
Down‐time for Standard & Callisto LNA
