Antenna Scatterers Analysis Program

Source Code Description: Subroutine GNF


PURPOSE: to calculate the near-zone electric field of a sinusoidal electric monopole.

gnf0.gif 2.57 K

METHOD: An electric line source is located on the z axis with endpoints at z1 and z2 as shown in the above figure. Let the electric monopole have the following current distribution:

gnf1.gif 1.42 K

where I1 and I2 are the endpoint currents, g is the complex propagation constant of the medium, d = z2 - z1 is the source length. The cylindrical components of the field are E(q) = 0 and

gnf2.gif 2.56 K

gnf3.gif 2.09 K

where h is the intrinsic impedance of the medium and where (r,f,z) denotes the cylindrical coordinates in a coordinate system centered at the endpoint of z1.

These expressions exclude the field contributions from the point charges at the endpoints of the line source, since these charges disappear when two monopoles are connected to form a dipole.

Let the coordinate s measure distance along the test monopole with the origin at (XA, YA, ZA). From any point X,Y,Z a line is constructed perpendicular to the monopole. SZ denotes the s coordinate of the intersection of this line with the monopole. The length of the line is the radial coordinate r and RS denotes r2. R1 and R2 are the distances from (XA, YA, ZA) and (XB, YB, ZB) to the point (X, Y, Z). In the statements above statement 1, the above equations are solved; and after statement 1, the cartesian components (Ex, Ey, Ez) of the field are determined. If a ground plane is present (IGRD>0) the reflection coefficients are applied to the cartesian components before returning to the calling program.



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Last modified on: 3 Nov 2007