Small dielectric-loaded antennas with filter response characteristics and low proximity effects for 3G and Bluetooth applications

Abstract

Handset design teams are returning to the difficulties that are imposed by frequency division duplex architectures, once a feature of first generation analogue phones, and now brought into the spectrum of 3G services as defined by the IMT-2000 specifications. As new functionality is brought into the handset, so new solutions to the receiver circuitry are required to mitigate interference. It is the objective of this paper to demonstrate how effectively a dielectric loaded bifilar helix antenna researched by Sarantel can solved these aforementioned problems. This paper describes an antenna topology that maintains a high cross-polar gain, is very small and is power efficient. The antenna boasts an alignment of electric and magnetic minima as well as a far field minimum directed towards the users head together with balanced electric field loading across a dielectric core. These attributes minimise the near-field electromagnetic energy that is offered to and dissipated in the user.