## Interaction Approximation Range (KH)

Purpose: To set the minimum separation distance for use of a time-saving approximation in filling the interaction matrix.

Card:

```     _________________________________________________________________
/2|  5|   10|   15|   20|    30|    40|    50|    60|    70|    80|
/  |   |     |     |     |      |      |      |      |      |      |
|   |   |     |     |     |      |      |      |      |      |      |
|KH |I1 | I2  | I3  | I4  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |
|   |   |     |     |     |      |      |      |      |      |      |
|   | B | RKH |  B  |  B  |   B  |   B  |   B  |   B  |   B  |   B  |
|   | L |     |  L  |  L  |   L  |   L  |   L  |   L  |   L  |   L  |
|   | A |     |  A  |  A  |   A  |   A  |   A  |   A  |   A  |   A  |
|   | N |     |  N  |  N  |   N  |   N  |   N  |   N  |   N  |   N  |
|   | K |     |  K  |  K  |   K  |   K  |   K  |   K  |   K  |   K  |
|   |   |     |     |     |      |      |      |      |      |      |
|  The numbers along the top refer to the last column in each field |
|   |   |     |     |     |      |      |      |      |      |      |
```
Parameters:
Integers - None
Decimal Numbers
RKH (F1) - The approximation is used for interactions over distances greater than RKH wavelengths.
Notes:
• If two segments or a segment and a patch are separated by more than RKH wavelengths, the interaction field is computed from an impulse approximation to the segment current. The field of a current element located at the segment center is used. No approximation is used for the field due to the surface current on a patch since the time for the standard calculation is very short.
• The KH card can be placed anywhere in the data cards following the geometry cards (with FR, EX, LD, etc.) and affects all calculations requested following its occurrence. The value of RKH may be changed within a data set by use of a new KH card.