Study of a wideband sinuous feed for reflector antenna applications

[摘要] ENGLISH ABSTRACT: This thesis presents a thorough study of the printed sinuous antenna and its characterisationas a feed for re ector antenna applications. Two di erent techniques are usedin this study, namely a parametric study and an e cient surrogate based optimisationstrategy.A planar sinuous antenna over a re ecting ground plane, with no absorber lining, isdesigned following a parameter study from which e ective design guidelines are derived.The designed prototype displays a bandwidth ratio of more than 3 : 1 from 1:9����6:2 GHz,at a measured return loss of 10 dB, representing a signi cant improvement over the octaveband previously achieved with a similar antenna.An optimisation based approach is followed in formally investigating a conical sinuousantenna over a re ecting ground plane. An e cient surrogate based optimisation strategy,in which the antenna's response is approximated by a Kriging model, is used. The searchfor optimal design parameters as well as improvements in the accuracy of the Krigingmodel is accomplished by using expected improvement as the in ll sampling criterion.The antenna is optimised for return loss, aperture e ciency for a prime-focus paraboloidre ector as well as cross-polarisation and results from the optimisation are used to derivee ective design guidelines and performance limitations. The investigations are conductedfor the 2 ���� 6 GHz band and the obtained results can be easily applied for designs withwider bandwidths. Simulation results reveal improved return loss, aperture e ciency andcross-polarisation performances compared to what has previously been reported for thisantenna.

[发布机构] Stellenbosch University