Towards a better dielectric rod antenna

Dielectric rod antennas (polyrods) have been the subject of considerable analysis and measurement. Even so, design philosophy is limited to guidelines, usually aimed at maximising gain, without consideration of those other attributes that would make the polyrod an attractive moderate gain antenna. Polyrods have been used as reflector type antenna feeds in the form of short cylindrical rods, as backfire elements, or with waveguide horn launchers. However, feeds with sufficient directivity, adequate side lobes, cross polarisation performance etc. for offset reflector geometry have not received much attention. A simplistic physical model of how the rod works is put forward and from reasoning based on this a polyrod design of good performance is obtained