Optimisation methods applied to horn antennas

Computer-aided design and optimization techniques are demonstrated to be of use for complex antennas such as horns. Horn antennas feature a radiation pattern and gain which depend on the size of the aperture and the distribution of amplitude and phase of the fieldstrength at the aperture. The distribution is significantly affected by the shape of the longitudinal section of the transition between waveguide and aperture. Consideration is given to a square aperture with a square waveguide feeder. A stepper profile is employed to model the transition region. A four-dimensional vector is defined to approximate the gain gradient obtained by incremental variation of the lateral lengths of the stepped profile. The method can then be employed to indicate the direction of maximum gain increase. Experimental results with an actual antenna confirm the expected gain optimization.