Space Segment - Payload, Core Competitiveness, Advanced Technology
08 March 2017
The existing TNC connectors under ESCC specification are not optimized regarding their multipactor discharge, corona and power handling capabilities.
The new generations of satellites request more power in coaxial connectors from L-band & C-band. The needs to improve the performances of the TNC series is demonstrated To improve their capabilities in term of power handling a study of their limits concerning the multipactor effect was necessary in order to find some solutions. In addition, the power handling is limited by the thermal heating linked to the power dissipation due to conduction and dielectric losses.
Concerning multipactor phenomena and corona effect, one important parameter is to avoid the gap without dielectric between the inner connector’s contact and the body, and maintain the dielectric of cable with the connector. For limiting multipactor effect it’s important to use materials optimized for multipactor effect point of view. For corona, the venting of the connector has been optimized.
The last parameter to be improved is the Passive Intermodulation (PIM). To minimize the level of passive intermodulation, interfaces between metallic elements must be limited, and sharp angles must be also avoided. It’s also important to avoid the micro cavities and improve the current continuity between parts of the connector.
The main goal of this contract is to develop, create and qualify a complete range of TNC Very High Power coaxial connectors to replace the waveguides solutions in L and C band.
This series of TNC connectors should be 100% compatible with the currently TNC connectors available on the market.
Additionally to his development, Radiall is writing the detail specifications for each type of connectors to be introduced in the ESCC standard.
The TNC Very High Power connectors series improve the power performance of the current TNC connectors under ESCC specification by more than 3000%.
With the existing TNC connectors (ESCC340200803 for example, the RF power handling power is limited at 30W at 1GHz, +25°C, and only 12W at +100°C (due to the power derating in temperature). With the new series, the RF power Handling power at 1GHz, +100°C is 400W.
These new TNC VHP connectors are multipactor free
The main benefit is the possibility to replace the waveguide solutions by a coaxial solution: easier to integrate, easier to modify the configuration of the integration, and also cheaper than waveguides products.
To benefit of these new RF performances, it is very important to use the pairs of connectors from this new series.
The variants of the new series of TNC VHP connectors uses all the PTFE insulators on their interfaces, and a Fluoroloy H material inside of them to dissipate dissipate the temperature of the center contact towards their body. Their internal designs have been also optimized to limit the PIM level. There is no Nickel material used in these TNC VHP connectors.
A hermetic adaptor (female to female) has also been developed to be used as tooling for thermal vacuum chamber in order to apply the RF power to the new connectors during their testing.
The new solutions used in the design of this connector series have been studied and evaluated in ARTES 5 on three variants of connectors in L and C Band. In ARTES 3-4, before to start the qualification, Radiall has studied, developed and optimized the design of the raw parts to limit their numbers. The main goals are to reduce the price of the connectors.
After this stage, Radiall has completed the range of the TNC Very High Power with fourteen variants. All of them have been qualified under ESCC3402 specification amended and ESCC3408 for cable assemblies.
All qualification tests under ESCC specifications have been done: according to ESCC3402 for connectors and ESCC3408 for cable assemblies
The main performances are:
Frequency band DC to 8GHz:
Female connectors ,Adaptors and Flexible cable assemblies:
Multipactor: >2000Wpp in L-band at 1GHz at -65°C and +100°C
Power Handling (CW): 400W (250W*) in L-band (2GHz),
300W (150W *) in C-band (4GHz) at
Corona: >120W CW in L-band (1GHz)
PIM: -140dBm with two carriers of 50W 7th order at L-band
(validated during Artes 5)
*For Semi-Rigid cable
The ESCC details specifications have been written and validated between ESA, CNES and Radiall.