Description
Priority 2 activities will only be initiated on the explicit request of at least one delegation.
The objective of this activity is to develop new thermal blankets (MLI) suitable for the areas adjacent to antenna farms with strong transmitted signals and high sensitivity in the receivers. The new MLI shall be designed and manufactured considering the latest advances in the mitigation of PIM.
Targeted Improvements:
Those payloads using the new low PIM MLI will benefit from very low passive intermodulation (below -150 dBm at 3rd PIM order) when illuminated with two tones or more with RF power levels around 53 dBm each. This means an improved ratio Tx versus PIM of more than 200 dBc compared to the typical existing one <180 dBc.
Description:
Recent ESA projects such as Alphabus and ATV have experienced the generation of RF interference at the antenna farms caused by the Thermal blankets (MLI). The actual composition of the MLI outer layers and typical elements of these blankets are potential generators of passive intermodulation products (PIM). This interference can cause total lost of the receive chain. Antenna side lobes are the main contributors to the interference when illuminating conventional MLIs.
Present studies have indicated that the MLI is composed by several elements, which are prone to generate high levels of PIM. Such elements are rivets, grounding elements, wires, attachments and other metal-based parts. In addition, the so-called folding techniques, are very sensitive as well as the methods used for cutting the edges of the MLI.
Other recent investigations in the frame of ATVs telecom anomaly (communications link between ATV and Earth) have indicated that the surface composition (such as Germanium) of the outer layers of the MLI play an important role in the level of PIM generated. In some particular cases, the migration of microscopic metallic particles from inner layers to the outer layers was the cause of this unwanted interference.
The activity will focus on the developing of new coatings to reduce potential PIM emission as well as innovative masking techniques to completely mitigate this effect when generated from rivets, bolts, grounding wires, etc.
The new design shall also complete the testing campaign with preliminary vibration tests of the MLIs. It is confirmed that during launch, for some types of MLIs the coating particles spreads to unwanted areas where PIM is created. The novel blankets will be designed to operate at any frequency band between L and K band.
Work Logic
- Investigation of materials and coatings suitable for its use in MLIs and with low PIM generation.
- Testing at sample level of a number (at least 10) of surface finishings.
- Design and manufacture of full MLI samples (at least 5) with all type of elements prone to generate PIM (ground wires, rivets, cut edges, folded sheets, etc ..) and using the selected coatings above determined. This phase will include novel techniques to mask the potential PIM generators.
- Testing of full MLI samples
The activity shall produce 10 samples of MLI and 5 full representative EM MLI samples.
Procurement Policy: C(1) = Activity restricted to non-prime contractors (incl. SMEs). For additional information please go to EMITS news "Industrial Policy measures for non-primes, SMEs and R&D entities in ESA programmes".