Modelling of a Dual-Band Backfire-Fed Dielectric-Loaded Forked Helix Loop Handset Antenna with the FDTD Method

TitleModelling of a Dual-Band Backfire-Fed Dielectric-Loaded Forked Helix Loop Handset Antenna with the FDTD Method
Publication TypeConference Paper
Year of Publication2000
AuthorsCai, M, Wingfield, A, McEvoy, P, Vardaxoglou, JC, Agboraw, E, Leisten, O
Conference NameMillennium Conference on Antennas and Propagation (AP2000)
Pagination4
Conference Start Date09/04/2000
Conference LocationDavos, Switzerland
Abstract

Miniature dielectric-loaded personal telephone antennas are low SAR radiators due to reactive field concentration towards the antenna’s centre and a horizontally placed near field null. A single-band design using this geometry has been successfully analysed in the past by Agboraw et al [1]. Similar designs can be made dual-band with slight alterations to the design, though the performance requires careful examination. In this paper we introduce and analyse a dual-band backfire-fed dielectric-loaded antenna using a forked-helix geometry. Two distinct narrow-band coupled responses, typical of a forked helix antenna, can be obtained each resulting in a fractional bandwidth of about 5%. This principle has been applied to the dual-banding problem by forking the helix resonators into parallel paths of slightly differing lengths. In order to simulate these accurately, we have used an advanced Finite Difference Time Domain (FDTD) method. We have also compared the input impedance results of an air-loaded scaled antenna calculated by the FDTD program and Method of Moments software. The inclusion of the coaxial cable feeding the antenna is examined.

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