Piecewise linear (PWL) spline-profiled pyramidal horn
Image of the Piecewise linear (PWL) 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 piecewise linear 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 PWL (piecewise linear) sections followed by the pyramidal flare to reach a specified aperture size.

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
Normalised radiation pattern cuts at the centre frequency