Pyramidal horn design under constraints on half-power beamwidth

Summary form only given. A number of expressions useful for the pyramidal horn design are presented. Our design takes into account the half-power beamwidth, and is an approximate numerical one. Two sets of equations associated with the essential characteristics of a horn and its radiation pattern have been derived. The first one relates the half-power beamwidth (HPBW) in the two principal planes with the side lengths and the parameters s and t of the horn. The second one associates the parameters s and t with the aperture length, the directivity and the half-power beamwidth in the principal planes. The main characteristic of the design procedure is the choice of s and t parameters. We start from the achievement of optimality in one dimension and the determination of the characteristics in the other so that the constraints can be fulfilled. The optimality has been obtained by giving to one of the parameters s or t the optimum value, i.e. s=0.25 or t=0.375. The half-power beamwidth ratio HPBW/sub H//HPBW/sub E/ determines the parameter which has to take the above value. When the ratio is bigger than 1.15, s becomes 0.25 and vice versa. It is noticed that by taking the inverse ratio of HPBW we could start from the other parameter. In this case the results are not the same. So the proper method of design is to find the best solution of the above two. Some characteristic examples are presented to show the usefulness of the proposed method.