Minimise pattern degradation when subreflector vertex shaping is used to improve feed match

摘要: A knob placed at the vertex of a subreflector to reduce mismatch in shaped Cassegrain antenna can significantly degrade radiation pattern and efficiency. practical procedure is described lessen these effects. Best results are obtained using cosine-squared-shaped knob, keeping low height base within feed blockage region. The importance simultaneously optimising for return loss, efficiency sidelobe level emphasised.