It is known that the 1-18 GHz Double Ridge Guide Horn (DRGH) antenna is highly sensitive to tolerances in manufacturing. Since a typical DRGH antenna is constructed from a number of individual parts, tolerances in the machining, even when numerically controlled, and errors in the assembly can easily lead to gaps between subsections. Performance deviations, most notably resonances in the boresight gain and VSWR was observed in a number of manufactured 1-18 GHz DRGH antennas. The exact cause of the performance deviations had to be determined in order to identify which sections of the antenna need to be redesigned in such a way that the effects of the manufacturing and assembling tolerances on the performance of typical mass produced DRGH antennas are reduced or eliminated. It was hypothesised that gaps most notable in the waveguide launcher section and especially the coaxial feeding section is the cause of the sharp resonance effects. This hypothesis was confirmed during the study. A highly accurate Method of Moments (MoM) numerical model of the 1-18 GHz DRGH antenna was developed, gaps were then implemented in between various parts of the model and the results observed. Based on these results a new improved 1-18 GHz DRGH antenna was designed with reduced sensitivity to manufacturing tolerances and improved performance. / Dit is alombekend dat die 1-18 GHz Dubbel Rif Golfleier Horing (DRGH) antenna baie sensitief is vir vervaardigings toleransies. 'n Tipiese DRGH antenna bestaan uit verskeie individuele onderdele. Toleransies in vervaardiging, selfs al word die proses numeries beheer, kan dus lei tot spasies tussen verskillende dele. Die waarneming van verswakte werkverrigting, meer spesifiek resonansies in die wins en Spannings Staande Golf Verhouding (SSGV) by 'n aantal vervaardigde 1-18 GHz DRGH antennes het gelei tot verdere studie. Om die 1-18 GHz ontwerp minder sensitief te maak ten opsigte van toleransies, moes die presiese oorsaak van die verswakte werkverrigting bepaal word. Aan die begin van die studie was die vermoede dat spasies in veral die golfleierlanseerder en meer spesifiek die koaksiale voer seksie, die oorsaak is van die resonansies. Die hipotese is in die daaropvolgende ondersoek bevestig. 'n Hoogs akkurate Metode van Momente (MvM) numeriese model is vir die 1-18 GHz DRGH antenna ontwikkel. Spasies is tussen verskeie parte van die model ge-inkorporeer en die resultate is ondersoek. 'n Nuwe verbeterde 1-18 GHz DRGH antenna op die ondersoek gebaseer, is ontwikkel. Die antenna het verminderde sensitiwiteit ten opsigte van vervaardigings toleransies sowel as verbeterde werkverrigting. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / Unrestricted