Waveguide-fed Smooth Spline Profiled Pyramidal Horn
Image of the Waveguide-fed Smooth Spline Profiled Pyramidal Horn.

The geometry of a rectangular horn is more suitable for array applications as the geometrical efficiency within the array cell is higher compared to a circular horn. Conventional pyramidal horns have an aperture efficiency of approximately 50 %, but it is possible to achieve efficiencies close to 100 % by optimising the flare profile and, in turn, improve overall array efficiency. The smooth spline profiled horn described here achieves an aperture efficiency of approximately 80 %.

The horn consists of a rectangular waveguide section, a mode converter and a pyramidal flare. The mode converter consists of five control points for the profile of both the width and height. The aperture’s width and height itself, forms the sixth control point for the horn’s width and height profile. A spline curve is then fitted through these control points to form the geometry of the horn.

The bandwidth for the PWL spline profiled horn the bandwidth is less than a conventional pyramidal horn as it is limited by the pattern performance. For gains higher than 18 dBi the overall length is less than a conventional horn of the same gain.

Typical radiation pattern at the centre frequency; Typical normalized radiation patterns at the centre frequency.