Antenna Scatterers Analysis Program

Source Code Description: Subroutine MAIN


PURPOSE: to control the input, output, and the flow of calculations,

METHOD: The Main program controls the flow of the required calculations by calling only a few subroutines. These subroutines in turn call other subroutines which actually do the required calculations. The order of the calling sequence is diagrammed after the listing for the main program.

The DIMENSION statements at the beginning of the main routine provides the required storage for a wire structure with up to 50 segments, 60 nodes and 60 dipoles without the presence of a ground plane. If a ground plane is present one-half of the reserved storage is required for the image, therefore a wire structure with up to 25 segments and 30 nodes can be analyzed.

NM denotes the actual number of monopoles (segments), INM is the corresponding dimension, and the dimension for CG, VG, and ZLD is twice INM. The second subscript for MD always has a dimension of 4 to correspond to the number of segments meeting at a given node.

N denotes the number of simultaneous linear equations and ICJ is the corresponding dimension.

The dimension for C is

(ICJ * ICJ + ICJ)/2.

In the statements above statement 4, the initial conditions and defaults are established, After calling subroutine READD to determine the input parameters, the IF statements output the parameters to be used for the calculations. In the DO LOOP ending at statement 7, the the input data of the structure geometry is stored in order to recall if the structure is to be moved for ground plane calculations.

After the image structure is generated and structure location is coved, subroutine SORT is called to determine the dipole modes. Prior to calling SGANT, the load and generator information is established,

Subroutine SGANT is then called to calculate the elements of the impedance matrix. If FEED or GENERATOR are specified by the input data stream, subroutine GANT1 is called to solve for the current distribution due to these forcing functions.

In the DO LOOP ending with statement 29, subroutine GNFLD is called to calculate the near-zone field for the current distribution of the subroutine GANT1.

The subroutine GFFLD is called for the far-zone field of the current distribution of the subroutine GANT1 in the DO LOOP ending at statement 35. The subroutine GFFLD is called again in DO LOOPs ending at staterents 42 and 51, if bistatic and backscattering calculations are requested by the input data stream.


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Last modified on: 3 Nov 2007