Far field projection
The FAR computer code, which post processes the results of a Finite Difference Time Domain (FDTD) code to produce far-field quantities from near-field values, is described. The integral equation and differential equation approaches are two methods of calculating the radiation and scattering effects of systems. Each method has practical limitations when used in general application codes. For instance, integral equation approaches such as the method of moments usually consider only perfectly conducting wires and patches in the frequency domain and the differential equation approaches such as FDTD, while applicable to multimedia and the time domain, are constrained to finite volumes determined by the specific computer memories. The FAR code allows the near-field details in the time domain modeled by FDTD codes to be extended to the far-field. This combined FDTD-FAR code set greatly extends the class of numerical electromagnetic modeling problems that can be treated with discrete differential equation methods. The FAR code uses the equivalence principle. Specifically, the code utilizes the tangential electric and magnetic fields at a specified surface of the FDTD computational volume and calculates the resulting far-fields from the equivalent magnetic and electric sources. In this process the sources of errors are sampling density, the length of the excitation pulse, the total time history record length, the time step size, and the size of the FDTD volume. The FDTD-FAR approach will be illustrated with a pulse driven array of dipole elements. The far-field time histories and the resulting frequency domain antenna patterns will be presented. The sizes of the various errors in this approach will be discussed in detail. The efficacy of this approach will be contrasted with conventional methods. 4 refs., 10 figs., 1 tab.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6314095
- Report Number(s):
- UCRL-100198; CONF-890393-2; ON: DE89010243
- Resource Relation:
- Conference: Applied computational electromagnetics conference, Monterey, CA, USA, 20 Mar 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ELECTROMAGNETIC FIELDS
COMPUTER CALCULATIONS
COMPUTER ARCHITECTURE
ELECTRIC DIPOLES
F CODES
FINITE DIFFERENCE METHOD
FOURIER TRANSFORMATION
FREQUENCY DEPENDENCE
COMPUTER CODES
DIPOLES
INTEGRAL TRANSFORMATIONS
ITERATIVE METHODS
MULTIPOLES
NUMERICAL SOLUTION
TRANSFORMATIONS
657002* - Theoretical & Mathematical Physics- Classical & Quantum Mechanics
990220 - Computers
Computerized Models
& Computer Programs- (1987-1989)