HF antenna with convex reflector - with concentric grooves on its reflecting surface to maintain wave polarised sense

摘要

An auxiliary reflector is an aerial haVing a number of auxiliary reflectors electromagnetic coupling between a horn of the aerial and a principal is convex in shape with a number of concentric grooves (30) formed in its reflecting surface to maintain the sense of polarisation of waves received by the aerial. Where the bandwidth of the aerial has upper to lower frequency ratio of 1.5 or less, the grooves have the same width and depth while for ratios greater than 1.5 the width of grooves decreases towards the reflector centre while the wall thickness increases. For receiving plane waves, the groove walls are parallel to one another, while for spherical waves the walls are triangular in section having a common summit height. The aerial operates in the GHz range.