Background and justification:

Direct Radiating Antenna arrays (DRAs) are an emerging solution to offer multiple beam, cellular-like coverage to satellite communication services, evolving to meet the demands for high data-rates, capacity and availability over a flexible area. A DRA array provides several advantages to the satellite: for downlink, an improved Equivalent Isotropically Radiated Power (EIRP), due to the smaller size of the beam; for uplink, an improved Gain-to-noise-Temperature (G/T).

The activity shall investigate the change in SEY (Secondary Emission Yield) properties due to storage conditions prior integration in the satellite. This parameter has a direct impact in the power handling (Multipactor threshold) of the RF component. The activity shall cover the changes in the threshold over time at typical storage conditions. To achieve successful results, the activity shall commence with a review of the Hatch-Williams curves with new test samples. These samples shall be used for the whole duration of the activity to study the aging process.

ESA?s Soil Moisture and Ocean Salinity (SMOS) mission launched in 2009 is based on an L-band interferometric radiometer providing images of the entire earth globe every three days. Several studies have been conducted in the past few years to define a different antenna configuration which could allow to improve the image quality and simultaneously reduce the imaging time.

Today, reference oscillators are based on a quartz resonator which is carefully sheltered in order to provide a very stable environment to this key component which in turn provides a very stable and low phase noise reference. This type of oscillator also called Oven Controlled Oscillator (OCXO) is the core technology in most space products requiring either stable frequency or low phase noise or both. Though far more recent on the market, MEMS oscillators are already as good as TCXO while being much smaller (hybrid assembly as compared to single chip solution).

The exploitation of the wide bandwidth signals in the lower GNSS L-band is expected to be of interest for mass-market user equipment (UE) in order to improve significantly code-based position accuracy in location-based services.

Quantum degenerate gases such as Bose-Einstein Condensates (BECs) are key tools for ultimate precision quantum technologies in space. On earth, gravity prevents long measurement times except in experiments with prohibitively large footprints (10m), however in orbit or in deep space the chilliest terrestrial atomic clouds would take minutes to expand to a radius of 1cm which corresponds to 100km of ballistic free-fall.

The increased need for accurate knowledge of amplitude and phase antenna patterns for a very broad frequency range and over a large thermal range is a reality for a multitude of space applications. Among them are the high accuracy Radio Science Experiments for ranging and radio occultation that require accurate knowledge of the phase information. This enable the characterisation of the thermo-elastic effects provided that test techniques are developed in a temperature range down to -140C.

With state-of-the-art polishing techniques straylight from surface roughness is decreased and straylight induced by contamination is becoming one of the main contributors to the straylight performance. It is then important to rely on representative models for contamination induced straylight. Typically, industry is using models coming from literature, which can lead to very different results. The activity shall include the following tasks : - A critical review of the existing models shall be performed.