入/4 Printed Monopole Antennas for 2.45GHz

1.Preface

Taking the demand for small size,easy fabrication and low cost into account in the developoment of low-power radion devices for short-rang 2.4GHz applications,a quarter wavelength monopole antenna implemented on the same printed circuit board as the radion module is a good solution .A printed quarter wavelength monopole antenna is very easy to design and can be tunned simply by slight changes in length.

This article presents basic guidelines on how to design such an antenna for use together with the nRF2401 Single chip Transceiver and the nRF2402 single chip 2.4GHz transmitter.

The described antenna should be fabricated on standard 1.6mm low cost RF4 printed circuit board (PCB).

2.Basic properties of a quarterwave monopole antenna

A quarterwave monopole is a ground plane dependent antenna that must be fed single-ended.The antenna must have a grount plane to be efficient.The length of the monopole PCB trace mainly determines the resonant frequency of the antenna.
Because of the very wide gain bandwidth of the quarterwave monopole,the length of the monopole PCB trace is not too critical.But like any other antenna types,the gain of a quarterwave monopole antenna will vary if parameters in the surroundings like case/box materials.distance to the ground plane,the size of the ground plane,width and thickness of the pcb trace are varied.If any of there parameters are changed,a retuning of the monopole pcb trace length may be neccessary for optimum performance in each application.