Description
The objective of the activity is to design, manufacture and test a Ku- or Ka-band transmit or receive antenna based on reconfigurable actuators for large mobile terminals connected to Low Earth Orbit (LEO) satellites.Targeted Improvements:Enabling reconfigurable terminal antennas with scan angles up to 50-60 degrees exploiting active actuators like pin or varactor diodes, MEMS and other possible actuators with an overall antenna thickness below 10 wavelengths.Description:Today antennas for mobile terminals are repointing the pattern mainly using mechanical scanning or an electronic scanning. Mechanically scanning antennas with a medium thicknessare already available as products for trains and aeroplanes. They are still expensive, and their thickness is around 15-20 wavelengths. For electronically scanning antennas, one of the main complexities is associated to the realization of the beamforming network.Even if a single beam is required instantaneously, the requirements to scan this beam in a large field of view implies that the antenna must be able to create patterns in thousand different pointing directions. Among the available compact antenna technologies, active phased arrays with electronic scanning start being available in the market providing a good control on beam-steering and a moderate angular coverage. However, the complexity and cost of active antennas, particularly associated to the beamforming network contribution, is not compatible yet with the stringent requirements associated to mobile platforms.The objective of this activity is to use reconfigurable actuators, like pin diodes, varactor diodes, MEMS or other possible actuators to modify the array tapering and repoint the instantaneous beam pattern. These types of actuators are known since several years but only now they started being considered as mature enough for mobile terminal antennas. In particular, pin diodes act essentially as on-off switches while varactor diodes permit to modulate continuously the phase value. Hybrid architecture combining both pin diodes and varactors could be used to increase the phase-shift resolution required to cope with the stringent radiation masks associated to the different regulatory standards(ITU, ETSI, etc.) for transmitting antennas. Furthermore, pin diode-based architectures could achieve a passive amplitude control without using any power amplifier. Reconfigurable screens working as reflectors or lenses and adopting pin or varactors diodes have been successfully demonstrated in C, X, Ku and Ka bands. A natural evolution and extension, proposed here, consists in including these actuators inside a phased array in order: a) to significantly reduce the form factor of the antenna as compared to configurations adopting feeders quite far as compared to the screen position, and b) to significantly reduce the complexity of the antenna as compared to conventional active arrays. This new type of antenna architectures could be adopted on board mobile terminals like trains or buses.