No abstract

No abstract

A procedure for antenna parameter selections is proposed that considers the relationships between synthetic aperture radar performance and the antenna parameters of a parabola-type reflector antenna with a central flat dish. The effects of a central dish designed for weight reduction on the antenna beam pattern are also quantitatively analyzed using commercially available software based on the physical optics algorithm. The results of the theoretical analysis and simulation predict that a larger size of the central dish results in an increase in the sidelobe level, which is the reason for the increase in two important ambiguities, such as range ambiguity ratio (RAR) and azimuth ambiguity ratio (AAR). The dependence of RAR and AAR on Pulse repetition frequency is also analyzed and discussed.

Large spaceborne antennas should be lightweight, a factor related to the development costs of launch vehicles. In order to overcome this drawback, a feasibility study of a new carbon fiber reinforced polymer (CFRP) named M55J/RS3 is carried out for a synthetic aperture radar (SAR) reflector antenna. In particular, the high resolution of detected images is taken into consideration. To validate the electrical performance, a test of the CFRP specimen is fabricated, and the transmission/reflection coefficients are measured using a standard Xband waveguide. Finally, the effective complex permittivity and effective electrical conductivity are derived from the obtained measured data. By applying the derived conductivity to the simulation of the radiation pattern, antenna gain, and beamwidth-instead of relying on the assumption of a perfect electric conductor-variations in electrical performance are also investigated and discussed.