A new circular shape patch ultrawideband (UWB) single feed microstrip antenna is described in this paper. The radiated patch of the proposed UWB antenna is embedded with slots to improve the radiation characteristics ensuring a wide impedance bandwidth. In the ground plane, two rectangular rings slots are etched to provide proper impedance matching over a wide frequency range. The proposed single layer UWB with overall dimensions of 55 mm by 56 mm is fabricated using low cost 4.3 relative permittivity FR-4 substrate. From results obtained, the antenna can provide an impedance bandwidth ranging from 2.2 GHz to more than 12 GHz (138%) that is wider than the standard UWB band. In addition, the modified UWB antenna can enhance the gain to more than 6.6 dB, which is higher than that achieved by the ordinary UWB antenna by more than 16%. Comparison of the modified UWB antenna simulated and measured results shows a close agreement, which enable it to be a promising solution for many wireless applications such as UWB applications, X-band (8-12GHz) satellite communication, portable wireless devices, medical applications, positioning systems cognitive radio and WiMAX 5.4 GHz band application.

A new method of Differential Mobility Analyzer (DMA) operation using a Fast Scanning Differential Mobility Analyzer (FDMA) nanometer particle sizer has been implemented. By optimizing the flow and voltage ramps, improvements can be made in the FDMA's measurement size range, counting statistics and resolution. In this study, an electrostatic classifier was used to generate mono-dispersed particles of different sizes to calibrate the delay time of the FDMA. The aerosol from incense combustion could be measured directly by FDMA although the particulate concentration was as high as 1,011 particles cm-3. The resolution of the FDMA was 3 nm and better than the SMPS (10nm).