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<HTML><HEAD><TITLE>Generate Cylindrical Structure (GR)</TITLE></HEAD>
<BODY>
<H2><center>Generate Cylindrical Structure (GR)</center></h2>
<pre>
Purpose: To reproduce a structure while rotating about the Z-axis to form a
complete cylindrical array and to set flags so that symmetry is
utilized in the solution.
Card:
Cols Parameter
----------------
1- 2 GR
3- 5 I1
6-10 I2
11-20 blank
21-30 blank
31-40 blank
41-50 blank
51-60 blank
61-70 blank
71-80 blank
Parameters:
Integers
(I1) - Tag number increment.
(I2) - Total number of times that the structure is to occur in the
cylindrical array.
Decimal Numbers
The decimal number fields are not used.
</pre>
<ul>
<lh><b>Notes:</b></lh>
<li> The tag increment (I1) is used to avoid duplication of tag numbers in
the reproduced structures. In forming a new structure for the array,
all valid tags on the previous copy or original structure are
incremented by (I1). Tags equal to zero are not incremented.
<li> The GR card should never be used when there are segments on the Z-axis
or crossing the Z-axis since overlapping segments would result.
<li> The GR card sets flags so the program makes use of cylindrical
symmetry in solving for the currents. If a structure modeled by N
segments has M sections in cylindrical symmetry (formed by a GR card
with I2 equal to M), the number of complex numbers in matrix storage
and the proportionality factors for matrix fill time and matrix
factor time are:
<pre>
Matrix Fill Factor
Storage Time Time
------- ---- ------
No Symmetry N^2 N^2 N^2
M Symmetric Sections (N^2)/M (N^2)/M (N^2)/M
</pre>
The matrix factor time represents the optimum for a large matrix
factored in core. Generally, somewhat longer times will be observed.
<li> If the structure is added to or modified after the GR card in such a
way that cylindrical symmetry is destroyed, the program must be reset
to a no-symmetry condition. In most cases, the program is set by the
geometry routines for the existing symmetry. Operations that auto-
matically reset the symmetry conditions are:
<ul>
<li> Addition of a wire by a GW card destroys all symmetry.
<li> Generation of additional structures by a GM card, with NRPT
greater than zero, destroys all symmetry.
<li> A GM card acting on only part of the structure (having ITS greater
than zero) destroys all symmetry.
<li> A GX or GR card will destroy all previously established symmetry.
<li> If a structure is rotated about either the X or Y axis by use of
a GM card and a ground plane is specified on the GE card, all
symmetry will be destroyed. Rotation about the Z-axis or transla-
tion will not affect symmetry. If a ground is not specified,
symmetry will be unaffected by any rotation or translation by a
GM card, unless NRPT or ITS on the GM card is greater than zero.
</ul>
<li> Symmetry will also be destroyed if lumped loads are placed on the struc-
ture in an unsymmetric manner. In this case, the program is not auto-
matically set to a no-symmetry condition but must be set by a data card
following the GR card. A GW card with NS blank will set the program to
a no-symmetry condition without modifying the structure. The card must
specify a nonzero radius, however, to avoid reading a GC card.
<li> Placement of nonradiating networks or sources does not affect
symmetry.
<li> When symmetry is used in the solution, the number of symmetric
sections (I2) is limited by array dimensions. In the demonstration
deck, the limit is 16 sections.
<li> The GR card produces the same effect on the structure as a GM card if
I2 on the GR card is equal to (NRPT+1) on the GM card and if ROZ on
the GM card is equal to 360/(NRPT+1) degrees. If the GM card is
used, however, the program will not be set to take advantage of
symmetry.
</ul>
<hr>
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