Odendaal, J.W. (Johann Wilhelm)2014-02-112014-02-112013-09-042013Van der Merwe, PH 2013, An optimized dual-polarized quad-ridges horn antenna with pyramidal sidewalls, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/33343>E13/9/1014/gmhttp://hdl.handle.net/2263/33343Dissertation (MEng)--University of Pretoria, 2013.It is well known that quad-ridged horn antennas in general have impedance and radiation characteristics that are significantly worse than that of their double-ridged counterparts. Normally a voltage standing wave ratio (VSWR) of 3 over the operational bandwidth is used for the design specification of quad-ridged horn antennas. The bandwidth of operation is severely restricted due to the excitation of higher order modes in the co-axial to waveguide transition of the antenna. The higher order modes cause a break-up in the radiation pattern of the antenna and large dips in the boresight gain. The performance of the quad-ridged horn antenna with pyramidal sidewalls is improved by separating the antenna into the transition and flared horn sections, and optimizing these sections individually. It is shown that a transition section with a pyramidal cavity and steps, and a flared horn section with an exponential profile with a circular segment for the ridges deliver the best performance. These configurations for the transition and flared horn sections are combined in the complete antenna. The optimized antenna has a 12.5:1 operational bandwidth with improved performance in terms of the VSWR, the coupling between the ports and the boresight gain. A prototype of this antenna is manufactured. Good agreement between the measured and simulated performance is achieved.en© 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.Quad-ridged horn antennaDual-polarizationUltra widebandHigher order modesUCTDDissertation