Ultra wideband (UWB) technology plays a significant role in wireless communication. The complex antenna transfer function (CATF) of an UWB antenna provides important information required for better channel designs and communication systems. In this dissertation the CATF of a Double ridge guide horn (DRGH) antenna is determined and used as a standard antenna for UWB measurements. Two methods were used: the two antenna method in an anechoic chamber and a modified gain-transfer method in a compact antenna test range (CATR). Measurements were performed with a vector network analyser (VNA) in the frequency domain, in the anechoic chamber and the CATR. The distance measurements required to calculate the CATF from the S-parameter measurements were performed in the time domain. The CATF of the standard antenna was determined using two identical antennas and then it was shown that a modified gain-transfer method can be used to determine the CATF of any unknown antenna in a CATR, using the standard antenna as a reference. Some of the challenges were to obtain the correct equations and measurement method to obtain the CATF in a CATR. The standard antenna was used to investigate uncertainty contributions for the measurements in the CATR. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted