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Radio telescopes are susceptible to interference arriving through its sidelobes. If a reflector antenna could be retrofitted with an adaptive null steering system, it could potentially mitigate this interference. The design of a reflectarray which can be used to reconfigure a radio telescope’s radiation pattern by driving a null to the angle of incoming interference is presented. The reflectarray occupies only a portion of the rim of the original reflector and lays conformal to the paraboloid within this region. The conformal reflectarray contains unit cells with 1-bit reconfigurability stemming from two symmetrically placed PIN diodes. It is found that the dielectric and switch losses introduced by the reflectarray do not significantly affect the radio telescopes efficiency since the reflectarray is placed only along the outer rim of the reflector which is weakly illuminated. Simulation results of an L-band reconfigurable reflectarray for an 18 m prime focus fed parabola are presented. 

This paper presents full-wave simulation results of a reflector-reflectarray hybrid antenna used as a spatial beamformer for mitigating interference in radio astronomy applications. Such antennas employ fixed reflectors with electronically tunable reflectarray along their rim to dynamically form nulls in the direction(s) of interferer(s). Results from realistic models of such antenas demonstrate their potential in producing nulls and potentially effectiveness in mitigating interference from satellites with the field of view of the instrument. 

This paper proposes a composite reflectarray system for realizing a reflector antenna for radio astronomy applications. The system is equipped with a tunable reflectarray rim that enables nulls to be formed within the field of view and reduce the impact of interferers on the observations. Full-wave simulation results of a physical reflectarray system are presented to validate the concept. 

It has been recently demonstrated that modifying the rim scattering of a paraboloidal reflector antenna through the use of reconfigurable elements along the rim facilitates sidelobe modification including cancelling sidelobes. In this work we investigate techniques for determining the unit-magnitude weights (i.e., weights which modify the phase of the scattered signals) to accomplish sidelobe cancellation at arbitrary angles from the reflector axis. Specifically, it is shown that despite the large search space and the non-convexity of the cost function, weights can be found with reasonable complexity which provide significant cancellation capability. First, the optimal weights without any magnitude constraints are found. Afterwards, algorithms are developed for determining the unit-modulus weights with both quantized and unquantized phases. Further, it is shown that weights can be obtained that both cancel sidelobes while providing a constant main lobe gain. A primary finding is that sufficiently deep nulls are possible with essentially no change in the main lobe with practical (binary or quaternary) phase-only weights.