The boundary integral method coupled with the segmentation method have been used for the first time to analyzed Sierpinski carpet antennas of different order. The close agreement between calculated and measured results for resonant frequency and input return loss indicates that this technique can predict the impedance characteristic accurately. A novel double layered stacked microstrip Sierpinski carpet fractal antenna using a photonic bandgap structure is also presented. This proposed antenna has improved the impedance bandwidth five fold compared to an ordinary microstrip fractal antenna and its radiation pattern is improved due to the removal of unwanted radiation caused by the surface wave.

The boundary integral method coupled with the segmentation method have been used for the first time to analyze Sierpinski carpet antennas of different orders. As is evident front the close agreement between calculated and measured results for the resonant frequency and input return loss, this technique is found to predict the impedance characteristic accurately,. A novel stacked microstrip Sierpinski carpet fractal antenna using a photonic bandgap structure is also presented. Compared to an ordinary microstrip fractal antenna, which has a maximum bandwidth of 2%, the proposed antenna has a higher input impedance bandwidth of about 9%. The radiation patterns of the proposed antenna are improved due to the removal of unwanted radiation caused by, the surface wave. The experimental measurement results of the proposed antenna are presented in this paper. (C) 2001 John Wiley & Sons, Inc.

Although Microelectromechanical system (MEMS) technology has been used extensively in constructing microelectronic and micromechanical structures, there are very few reports on the research and development of MEMS antenna. This paper reports the investigation results of MEMS patch antennas in different shapes and structures. Like conventional patch antenna, MEMS patch antenna has narrow bandwidth, however, it is found among three basic shapes: circular, square and triangular.Square patch antenna has the best overall performance. Two simple methods to improve the performances of MEMS patch antenna are also proposed. When the feed inset position in polysilicon layer of a MEMS microstrip patch antenna is optimized, the impedance bandwidth of the antenna can be enhanced without deteriorating the radiation pattern of the antenna. Also, the resonance frequency of MEMS patch antenna is reduced by etching holes on the radiating patch.

A general method of analyzing fringe data from interferometric testing of optical surfaces is described. The method combines the surface optimization routine with the lens design software to simulate the optical testing and to reconstruct the testing surface. With this method the residual error requirement on null lens design may be relaxed; some alignment ambiguities can be removed; and the final surface figures and tolerances can be defined. Sources of error are discussed.