Wire Specification (GW)

Purpose:  To generate a string of segments to represent a straight wire.

Card:
           Cols  Parameter
          ----------------
           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:

           Cols  Parameter
          ----------------
           1- 2  GC
           3- 5  blank
           6-10  blank
          11-20  F1 - RDEL
          21-30  F2 - RAD1
          31-40  F3 - RAD2
          41-50  blank
          51-60  blank
          61-70  blank
          71-80  blank


Parameters:
        Integers
           ITG   (I1) - Tag number assigned to all segments of the wire.

           NS    (I2) - Number of segments into which the wire will be
                        divided.

        Decimal Numbers
           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)

           or

                        S1 = L/NS if RDEL=1.

Notes:
• 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 wire.
• 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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