Planar Monopole Family Proposed for Digital Portable Terminals

The use of a single antenna, which can cover a wide range of frequencies is a desirable feature for future wireless communications systems. The emerging self-organising and ad-hoc networks require more than an octave of bandwidth to facilitate multiband operation. The planar monopole family is proposed for use on digital mobile terminals. The simple square element with 2.25:1 impedance bandwidth ratio is described. The radiation pattern is shown to be quasi-omnidirectional within the impedance bandwidth. Attempts, which have been made to control the impedance bandwidth and minimise the physical size of the antenna are described. An antenna which has been optimised for future wireless networking bands and shown to operate from 1.6 GHz to 6 GHz is presented. Antenna parameters are compared for these elements and a method of moments code combined with the geometrical theory of diffraction is employed for modelling.