Additional Ground Parameters (GD)

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Additional Ground Parameters (GD)

Purpose: To specify the ground parameters of a second medium which is not in the immediate vicinity of the antenna. This card may only be used if a GN cart has also been used. It does not affect the field of surface patches Card:

         _________________________________________________________________
        /2|  5|   10|   15|   20|    30|    40|    50|    60|    70|    80|
       /  |   |     |     |     |      |      |      |      |      |      |
      |   |   |     |     |     |      |      |      |      |      |      |
      |GD |I1 | I2  | I3  | I4  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |
      |   |   |     |     |     |      |      |      |      |      |      |
      |   | B | B   | B   |  B  |  E   |  S   | CLT  | CHT  |  B   |  B   |
      |   | L | L   | L   |  L  |  P   |  I   |      |      |  L   |  L   |
      |   | A | A   | A   |  A  |  S   |  G   |      |      |  A   |  A   |
      |   | N | N   | N   |  N  |  R   |  2   |      |      |  N   |  N   |
      |   | K | K   | K   |  K  |  2   |      |      |      |  K   |  K   |
      |   |   |     |     |     |      |      |      |      |      |      |
      |  The numbers along the top refer to the last column in each field |
      |   |   |     |     |     |      |      |      |      |      |      |

Parameters:

Integers
  All integer fields are blank..
Floating Point
  EPSR2 (F1) - Relative dielectric constant of the second medium.
  SIG2 (F2) - Conductivity in mhos/mecer of the second medium.
  CLT (F3) - Distance in meters from the origin of the coordinate system to the join between medium 1 and 2. This distance is either the radius of the circle where the two media Join or the distance out the plus X axis to where the two media join in a line parallel to the Y axis. Specification of the circular or linear option is on the RP cart. see figure 16.
  CHT (F4) - Distance in meters (positive or zero) by which the surface of medium 2 is below medium 1.
  (FS) & (F6) - Blank.

Notes:

- The GD card can only be used in a data set where the GN card has been used since the GN card is the only way to specify the ground parameters in the vicinity of the antenna (see GN card write-up). However, a number of GD cards may be used in the same data set with only one GN card.
- GD cards may not be grouped together. If they are, only the lnformation on the last card of the group is retained.
- When a second medium in specified, a flag must also be set on theradiationpattern (RP) data card in order to calculate the patterns including the effect of the second medium. Refer to the radiation-pattern card write-up for details.
- Use of the GD card does not require recalculation of the matrix or currents.
- The parameters for the second medium are uset only in the calculation of the far fields. It is possible then to set the radius of theboundary between the two media equal to zero and thus have the far fields calculated by using only the parameters of medium 2. The currents for this case will still have been calculated by using the parameters of medium 1.
- When a model includes surface patches, the fields due to the patches will be calculated by using only the primary ground parameters. Hence, a second ground medium should not be uset with patches.

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