Low Profile Ku-Band Transmit/Receive Terminal ODU for satellite mobile communications.
The scope of the project has been to develop a terminal able to cope with all the technical and market requirements related to the broadband 2-way communication 'on the move' for mobile ground applications. TTI antenna could cover the market broadband satellite communication requirements, and is able to support data rates up to 40 Mbps for downlink and 2Mbps for uplink. The dual array antenna designed by TTI is believed to represent a world class antenna technology, which is able to provide Ku-band transmit-receive, dual linear and wide scan angle coverage, within the same planar apertures.
The terminal integrates a wide band passive radiation structures with polarisation tracking capability, full RF-transceiver, several axis motorised mechanical system and pointing-tracking.
Figure: Prototype antenna terminal
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Some of the key issues address for TTI antenna terminal have been: -
TTI has been able to develop an antenna terminal achieving a higher performance than existing solutions for a low/medium cost price range target, keeping the low profile of the terminal.
The antenna aperture is based on an array of wideband radiating elements fed from beamforming networks using a combination of printed suspended stripline and waveguide technologies.
The antenna subsystem is based on the integration of two independent array apertures, which are mechanically rotated in order to steer the beam in elevation. This concept only uses the front array panel as Tx antenna in order to avoid the undesired off axis radiation caused by the blockage of the rear array panel. The Rx signal is obtained from both array panels by combining the outputs of the arrays with the proper phase/time delay, increasing the antenna gain without raising profile.
A dual band/dual polarisation concept has been developed. This concept combines Tx and Rx in the same aperture allowing a significant reduction of the antenna size comparing to other systems that use separate Rx and Tx apertures.
The required dynamic pointing and Tx tracking processing are obtained by the integration of 4 motorizations (elevation, azimuth, Tx-phase adjustment and Tx-polarisation tracking) while Rx-phase adjustment and Rx-polarisation tracking are electronically performed.
The antenna subsystem is integrated with RF transceiver (optimised figures regarding noise and power) which components are distributed between mobile platform, fix platform (interface to the vehicle) and Rack.
The terminal subsystems includes antenna apertures and combination networks, RF-subsystem, mechanical motorization and structure, control subsystem and PAT. These subsystems will be integrated into a low profile ODU structure properly communicated to the developed IDU and Modem.
The project started at the end of 2007. The industrialised version of the prototype is available and satisfactory field tests have been performed.
The project is now completed.