The objective of this activity is implement reflectarrays to realize high-gain antennas on-board CubeSats missions. Special attention will be given to RF design optimization leading to enhanced efficiency and bandwidth as compared to existing designs. In terms of thermo-mechanical aspects the design will need be reach a flight ready level.

 

This activity will improve the usability of reflectarrays for space and is an important step to have a European reflectarray in orbit. Although this activity will focus on interplanetary missions operating in X-band, there are other opportunities for reflectarrays onboard CubeSats in other frequency bands, e.g., Ka-band. For this reason, an upgrade path from X- to Ka-band may also be considered during the activity.

For other missions like for example LEO missions (EO) the increase gain of the actenna (tipically 30db increase) will directly result in an enhacement of the scienc return.

 

 

In recent years, CubeSats have been gaining considerable popularity. Initially, work on CubeSats were mostly conducted by universities, but now other sectors, e.g., commercial business, government agencies, and military, are also interested in CubeSats. Recently, cubesats are being considered for operation beyond LEO, e.g., in deep-space (DS) missions. For such missions, high-gain antennas on-board the CubeSats are needed to ensure communications with Earth.

 

To realize high gain, several antenna solutions exist, but deployable reflectarrays are believed to be ideal candidates as high-gain antennas on-board a CubeSat. Although several institutions in Europe are working extensively on reflectarrays, most research on reflectarrays for CubeSats are non european. However, as compared to these designs several improvements can be implemented:

 

• The reflectarrays considered outside Europe are synthesized using a phase-only approach. Although efficient and easy to implement, the phase-only approach is an indirect synthesis strategy and may result in suboptimal designs, in particular in terms of bandwidth. Using a direct optimization technique, where all the array elements are simultaneously optimized, one have more control of the antenna performance, thus designs with enhanced performance can be achieved.

 

• Improved bandwidth: The reflectarrays currently considered are based on rectangular patches printed on a single-layer substrate. These elements are known to provide narrow bandwidth. For general applications the bandwidth and required data-rate offered by such antennas may not be sufficient. Direct optimization techniques have proven to provide designs with improved bandwidth compared to phase-only designs, and it is expected that wider bandwidth can be achieved using this design approach.

 

• Reduced losses: The losses in the reflectarray is one of the drivers that determine the performance of the antenna. For single offset configurations, the feed considered is offten a small microstrip patch array which generates the proper edge illumination. However, the losses associated to the patch array is high and in some examples almost 1dB in gain is lost due to the feed losses.

 

Any deployable elements in a satellite design introduce complexity and risk. However, the reflectarray design results in deployment similar to deployable planar solar panels. The activity will draw on experience and mechanisms designed and qualified for deployable solar panels adapted to the reflectarray.Thermal aspects will demand more attention than for solar panel design as any deformation of the panels will directly influence the performance parameters of the antenna.

 

In particular, the tasks that will be done in the frame of this activity are the following:

 

• Desing on the reflectarray

• Manufacture of the reflectarray

• Testing up to cubesat fligth qualification (RF and thermal Mechanical testing)

 

The entire activity will lead to a flight ready antenna for cubesats.