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A Space Based Radar Antenna Concept to Counter Camouflage and Concealment

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Conference paper with briefing charts

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This paper presents a novel concept for a low-mass 50m2 deployable P-Band dual polarisation antenna, noting that P-Band observations can penetrate dense forests and possibly penetrate the earth to support searches for tunnels and caves. P-Band is important because existing optical or radar instruments cannot penetrate the forest canopy or the earths surface in order to monitor suspicious activities. Existing space based Synthetic Aperture Radar SAR systems operate at a high frequency and the transmitted signals literally bounce off the canopy of these forests. Only with radars operating at P-Band or below can penetrate these forests. The antenna is designed to be used from a spacecraft in a low-Earth orbit. The antenna design has a monolithic array of feed and radiating patches bonded to a transversally curved structure consisting of two Kevlar sheets. The first sheet supports the array and the other sheet supports a ground plane. The two sheets are connected by a compliant Kevlar core that allows the whole structure to be folded elastically and to spring back without damage to its original shape on release. This structural concept has been given the acronym of FLATS Folding Large Antenna Tape Spring. Test-pieces have been made to demonstrate both the RF and mechanical aspects of the design, particularly the RF performance before and after folding the structure. It is concluded that the proposed concept is the design with the highest potential for large low frequency antennas for low-cost missions. The difficulty facing the SAR system designer is that existing instruments at C-Band 5.3 GHz already use antennas with areas greater than 10 m2, and to maintain the same SAR performance, the antenna area varies inversely with frequency. Thus, at P-Band 0.435 GHz an antenna of 50 to 100 m has to be launched and deployed in space. It is this packaging and structural problem and its unique solution that are the subject of this paper.

Subject Categories:

  • Structural Engineering and Building Technology
  • Active and Passive Radar Detection and Equipment
  • Unmanned Spacecraft

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