Improved design of an Ultra Wideband Universal Serial Bus device mounted antenna based on comparative radiation efficiency measurements

The present paper reports a planar, microstrip-fed Ultra Wideband (UWB) monopole antenna designed to operate inside a Universal Serial Bus (USB) dongle. The antenna was dielectrically loaded with a sandwich fabricated in commercial substrate. This design improves on a coaxial fed monopole presented earlier by showing a better matching through the UWB [3.1 - 10.6] GHz band. Wideband efficiency measurements were conducted, using the reverberation chamber technique and a cavity-based approach, called the source-stirred method. The dielectric loading implementation described here has a small impact on antenna radiation efficiency, with the loaded prototype having a figure higher than 78% over the UWB band.