scholarly journals Study of Factors Making Space-Contaminated Optical System Unusable

2012 ◽  
Vol 2012 ◽  
pp. 1-4
Author(s):  
Dakun Wu ◽  
Yanping Zhou ◽  
Fangkui Sun
Keyword(s):  
Optical System ◽  
Time Domain ◽  
System Performance ◽  
Finite Difference Time Domain ◽  
High Permittivity ◽  
Optical Surfaces ◽  
Particulate Contamination ◽  
2D Fdtd ◽  
Difference Time ◽  
Experimental Effort

Molecular and particulate contamination of space optical surfaces can be extremely detrimental to optical system performance. In order to determine whether optical system is unusable, we must do a lot of tests. For reducing experimental effort, computational criterion for unusable space optical system is put forward, which is based on experimentation and calculation by 2D-FDTD (finite-difference time domain). And then factors making optical system unusable are studied when distribution of light intensity is consistent with the criterion. Results show that small particulate is more detrimental to optical system than big one for particle with high permittivity is. The distribution of particles making optical system unusable is also obtained.

scholarly journals A Compact Wideband Stacked Antenna for the Tri-Band GPS Applications

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Maher M. Abd Elrazzak ◽  
M. F. Alsharekh
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Patch Antenna ◽  
Finite Difference Time Domain ◽  
Dielectric Materials ◽  
Scattering Parameters ◽  
High Permittivity ◽  
Perfect Matched Layer ◽  
Difference Time ◽  
Stacked Patch Antenna

A compact wideband stacked patch antenna is presented for the applications of GPS systems. This antenna covers the L1, L2, and L5 GPS bands of operating frequencies 1.575, 1.227, and 1.176 GHz, respectively. High permittivity dielectric materials are used to minimize the antenna dimensions. The obtained antenna is of dimensions  mm. To verify the design, the time dependence field distribution, the scattering parameters, and the radiation pattern are presented. The scattering parameters show that the antenna operates at the GPS frequencies with lower than  dB. The finite difference time domain (FDTM) with the perfect matched layer (PML) is used in the present analysis.

Quantifying Sub-gridding Errors in Standard and Hybrid Higher Order 2D FDTD Simulations

2021 ◽  
Vol 35 (11) ◽  
pp. 1428-1429
Author(s):  
Madison Le ◽  
Mohammed Hadi ◽  
Atef Elsherbeni
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Contrast Ratio ◽  
Higher Order ◽  
Fdtd Simulation ◽  
Fdtd Simulations ◽  
2D Fdtd ◽  
Difference Time

Sub-gridding errors for a 2D Finite-Difference Time-Domain (FDTD) simulation are compared for both the standard FDTD and Hybrid higher order FDTD cases. Subgridding contrast ratios of 1:3, 1:9, 1:15, and 1:27 are considered and analyzed. A correlation is seen between the increase of contrast ratio with the increase of sub-gridding errors for both standard and hybrid cases. However, a trend of errors reduction when using hybrid formulations over standard formulations is apparent for each contrast ratio.

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