Wire Specification (GW)
Wire Specification (GW)
Purpose: To generate a string of segments to represent a straight wire.
1- 2 GW
3- 5 I1 - ITG
6-10 I2 - NS
11-20 F1 - XW1
21-30 F2 - YW1
31-40 F3 - ZW1
41-50 F4 - XW2
51-60 F5 - YW2
61-70 F6 - ZW2
71-80 F7 - RAD
The above card defines a string of segments with radius RAD. If
RAD is zero or blank, a second card is read to set parameters to
taper the segment lengths and radius from one end of the wire to
the other. The format for the second card (GC), which is read
only when RAD is zero, is:
1- 2 GC
3- 5 blank
11-20 F1 - RDEL
21-30 F2 - RAD1
31-40 F3 - RAD2
ITG (I1) - Tag number assigned to all segments of the wire.
NS (I2) - Number of segments into which the wire will be
XW1 (F1) - X coordinate \
YW1 (F2) - Y coordinate > of wire end 1
ZW1 (F3) - Z coordinate /
XW2 (F4) - X coordinate \
YW2 (F5) - Y coordinate > of wire end 2
ZW2 (F6) - Z coordinate /
RAD (F7) - Wire radius, or zero for tapered segment option.
Optional GC card parameters
RDEL (F1) - Ratio of the length of a segment to the length of the
previous segment in the string.
RAD1 (F2) - Radius of the first segment in the string.
RAD2 (F3) - Radius of the last segment in the string.
The ratio of the radii of adjacent segments is
RRAD = (RAD2/RAD1)^(1/(NS-1))
If the total wire length is L, the length of the first segment is
S1 = L(1-RDEL)/(1-RDEL^NS)
S1 = L/NS if RDEL=1.
- The tag number is for later use when a segment must be identified,
such as when connecting a voltage source or lumped load to the
segment. Any number except zero can be used as a tag. When identify-
ing a segment by its tag, the tag number and the number of the segment
in the set of segments having that tag are given. Thus, the tag of a
segment does not need to be unique. If no need is anticipated to
refer back to any segments on a wire by tag, the tag field may be
left blank. This results in a tag of zero which cannot be referenced
as a valid tag.
- If two wires are electrically connected at their ends, the identical
coordinates should be used for the connected ends to ensure that the
wires are treated as connected for current interpolation. If wires
intersect away from their ends, the point of intersection must occur
at segment ends within each wire for interpolation to occur.
Generally, wires should intersect only at their ends unless the
location of segment ends is accurately known.
- The only significance of differentiating end one from end two of a
wire is that the positive reference direction for current will be in
the direction from end one to end two on each segment making up the
- As a rule of thumb, segment lengths should be less than 0.1 wave-
length at the desired frequency. Somewhat longer segments may be
used on long wires with no abrupt changes, while shorter segments,
0.05 wavelength or less, may be required in modeling critical regions
of an antenna.
- If input is in units other than meters, then the units must be scaled
to meters through the use of a Scale Structure Dimensions (GS) card.
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