Magnus Bonnedal

Activities in ACE WP 2.3-1 on wideband and multiband radiators

Developments in wireless communications and sensing require increasing wider frequency bands and that multiple functions can be provided by single antenna systems. This paper presents an overview of the activities of ACE work package 2.3-1, intended to gather and integrate expertise on a European level. We review here the progress of the partners and relate the work to other ACE activities.

The Antenna System for the TELE-X Nordic Communication Satellite

The paper describes the design and the measured performance of the antenna system for the TELE-X satellite, the Scandinavian direct broadcast and communication satellite. The two antennas are shaped, astigmatic double reflector systems. Good aperture efficiencies combined with low sidelobe and crosspolarization levels are demonstrated.

Improved GNSS radio occultation with the next generation GRAS instrument

The next generation GNSS radio occultation instrument under development at RUAG Space will take advantage of the new signals of Galileo, GPS, GLONASS, and Compass. The measurement performance is improved as compared to the present instrument generation that operates on the MetOp satellites. A tracking algorithm has been developed which ensures that all signal information throughout the atmosphere is made available for ground processing with a minimum of losses. Simulation results are presented for a demanding case of a rising occultation.

MetOp GRAS: Signal tracking performance results

The GRAS radio occultation instrument on board MetOp has continuously provided measurement data during almost four years. The measurement data are here used as a means to analyze the signal tracking performance of the GRAS instrument. The results demonstrate that the atmospheric Doppler shift is measured to an accuracy of 1.1 mm/s and that the on-board Doppler model is accurate within 4 m/s (or 20 Hz). It is also found that rapid signal amplitude fluctuation, exceeding 10 dB, frequently occur at higher altitudes than expected and that it is possible to improve the signal tracking during such events.

The Slotted Waveguide Arrays of the European Remote Sensing Satellites ERS-1 and ERS-2

ABSTRACT The European Remote Sensing Satellites, ERS-1 and ERS-2 were launched in 1991 and 1995. ERS-2 is operating and ERS-1 is presently used as backup. The satellites carry an Active Microwave Instrument which comprises a radar scatterometer measuring the wind speed and direction over the oceans and a synthetic aperture radar (SAR) for land mapping. These radars work at C-band, 5.3 GHz. Saab Ericsson Space was responsible for the electrical design and RF tests of the slotted waveguide antenna farm. Slotted waveguide antennas are very well suited for demanding requirements on accurate beamshaping, high gain, very low losses, and sidelobe control. Excellent agreement between theoretically predicted and measured performance has been verified by nearfield tests. The development procedure and our approach to solve certain critical design issues are described in the article.