## Helix - Spiral Specification (GH)

Purpose: To generate a helix or spiral of wire segments
Card:
Cols Parameter
----------------------
1- 2 GH
3- 5 I1 - ITG
6-10 I2 - NS
11-20 F1 - S
21-30 F2 - HL
31-40 F3 - A1
41-50 F4 - B1
51-60 F5 - A2
61-70 F6 - B2
71-80 F7 - RAD
Parameters:
Integers
ITG (11) - Tag number assigned to all segments of the helix or
spiral.
NS (12) - Number of segments into which the helix or spiral
will be divided.
Floating Point
S (F1) - Spacing between turns.
HL (F2) - Total length of the helix.
A1 (F3) - Radius in x at z = 0.
B1 (F4) - Radius in y at z = 0.
A2 (F5) - Radius in x at z = HL.
B2 (F6) - Radius in y at z = HL.
RAD (F7) - Radius of wire.

**Notes:**
- Structure will be a helix if A2 = A1 and HL > 0.
- Structure will be a spiral if A2 = A1 and HL = 0.
- Unless it has been fixed in the codes in circulation, the use of HL=0
for a flat spiral will result in division by zero in NEC-2. GH was a
non-official addition to NEC-2

- HL negative gives a left-handed helix.
- HL positive gives a right-handed helix.

*This file was last modified on Monday, *