Design of small ultra-wide band antenna

Abstract

A portable ultra wideband antenna composed of a printed monopole and a printed slot is proposed. The antenna is targeted for application in UWB systems, especially in mobile UWB communications. The proposed antenna is designed to have a wide operating bandwidth from 3.1 to 10.6 GHz, which is approximately a 110% bandwidth. Two type of feeding mechanisms (CPW fed and microstrip line fed) are studied for investigation of feed influence on radiation characteristics. Parametric studies on input impedance with variation of both slot and monopole shapes are conducted through the use of EM simulator, IE3D. Measured and simulated results are compared. Design guide and comments for the small UWB antenna will be shown. The first antenna designed in a manner of CPW which the feed, the printed monopole and the printed slot are located at the same side in co-planar structure. A wide impedance performance can be illustrated. Measured patterns show the antenna has a bi-directional radiation with certain cross-polar level radiation. On the other hand, one the proposed UWB antenna is studied. It is a case that the printed monopole and the printed slot are placed in different layers of the PCB. This UWB antenna is employed a microstrip line feed instead of a CPW feed. Obtained results show wider VSWR can be achieved.