{The document was scanned from the original thesis using Optical Character Recognition
in January 1998. Some errors or variations from the original may exist. Comments added to
clarify points that may not be obvious or to indicate changes to the original document are
inclosed in curly braces "{ }" such as this introduction. Some corrections (e.g. spelling)
and format editing were made without indication. Comments, editing, and scanning by R.L.
Cross, 1998, 1999, 2000
Last modified on: 6 September 2004.}
Please see also the quick reference for the user's guide which contains many useful tips and how to avoid pitfalls in using the code.
| Note that the whole text portion of the ASAP website including Users Manual, System Manual and other items (except for the executables and source) code is now available in one zip file from the download page. When it is unzipped keep the directory structure the same for the links to work. The executables and source code should be downloaded separately from the download page. |
The Antennas Scatterers Analysis program (ASAP) for thin wire structures in a homogenous conducting medium performs a frequency domain analysis of antennas and scatters, The program is applicable in the presence of either a perfect or a finite conductivity ground. This appendix will describe and explain the data cards necessary to execute the computer program. although the program was written for the IBM 360 computer system, it can be executed on another system with minor modifications. {Note: These modifications have been made.}
{The original computer system used punch cards for the input data. The terminology "CARDS" or card image is retained in the document. The equivalent is a line in a "plain ASCII" text file. The original output was to a line printer but is usually sent to a file in modern systems.}
The program utilizes piecewise sinusoidal expansion for the current distribution with Kirchhoff Current Law enforced everywhere on the structure, If the structure contains end points, the currents at these points are assumed to vanish.
The thin wire assumptions are questionable and the accuracy and convergence deteriorate if the radius of wire utilized for the structure exceeds 0.01 of a wavelength, if the longest segment is greater than one-fourth of a wavelength, if the length ratio of the longest and shortest segments exceeds 100, or if the total wire length is less than 30 times the wire diameter. If a wire is bent sharply to force a small acute angle (less than 30 degrees), the thin wire model is questionable. It is assumed that the wire conductivity greatly exceeds the conductivity of the ambient medium. For insulated wires, the dielectric layer is assumed to be electrically thin.
The minimum data necessary to execute the program is:
The program will default to the other parameters necessary. The default parameters are:
A more detailed explanation of the defaults will be discussed when the data card for the parameter is described.
In antenna problems, the output includes structure currents, impedance(s) of feed(s), gain, polar radiation plots, and near field calculations. In bistatic scattering problems, the output includes structure currents, complex elements of the polarization scattering matrix, polar reradiation pattern plots, and echo areas produced by a plane wave. For backscattering problems the output includes absorption, scattering and extinction cross sections in addition to the outputs of bistatic scattering. most of the outputs are suppressed and must be requested. Since the program can produce a large volume of output, care should be exercised until the user is familiar with the outputs.
{The output is divided into sections. Only those outputs requested by the user in the input are printed. Output is arranged by columns with headings at the top of the columns. The output is formatted for wide line printers. It will be necessary to use a text editor that allows long lines (such as the "freeware" Professional File Editor) that don't wrap or the output could be confusing. A web-browser actually works well as an output viewer and can also be used to copy and paste into other applications. "WRITE" for MS Windows will also work if the page setup is changed to landscape, the text is selected and the font is changed to a small enough monospace font such as 'Courier 7' }
The analysis program utilizes free format for the data cards, that is, the program utilizes character recognition to determine which parameters are being read. Data placement (location) on the input card is not critical. Blank characters, on all input cards but the COMMENT data card, are ignored and may be used at the discretion of the user. Since character recognition is used, only the first four characters of the key words must be present and correct. {However ALL CAPITAL LETTERS must be used due to the character recognition only including the uppercase set.}
The format for the COMMENT CARD utilizes standard FORTRAN format (i.e. 'C' in column 1 followed by at least four blanks). The COMMENT CARD is the only type of input card that position in the data block is critical . This (these) card(s) must be placed at the beginning of a data block. A data block is a series of related data cards.
Several data blocks may be used to define an analysis problem. This will become clear when the termination cards (END, STOP, or CHANGE) are discussed. There is no limit to the number of comment cards that may be used. As a check for the user, all input data cards will appear on the output as they appear in the input deck. The format of other data can be of one of two forms:
The type of format to use will be apparent as the individual data cards are discussed.
The numerical values for the parameters may be stated in any one of the following forms. The program will translate the number to the proper form for the specified parameter, either fixed or floating point. All of the following examples have the same value.
0.0001 or .0001 or 100.U or 1000 or .1M or 0.1M or .0000001K
where: U = 10E-6 M = 10E-3 K = 10E+3
{
The letter extensions U, M, or K to indicate engineering multipliers will not work with the new list inputs for GXZY or NEAR
}
This card is used to define the parameters associated with the wire utilized by the thin wire structure. Two options are available and are defined as:
The wire data card must appear in the first data block to define wire radius. The default value of the conductivity is 50 megamhos/meter (copper).
{To set perfect wire conductivity set the conductivity value negative.}
example:
WIRE( RADIUS=.001/ CONDU=28.5)
This card is utilized to define the parameters associated with the insulation of the wire
used for the structure to be analyzed. If this card is omitted, the program assumes that the
structure is uninsulated.
Four options are available and are defined as:
The conductivity and either the relative dielectric constant or the loss tangent (but not all three) options may be stated.
example:
INSULATION( RADIUS=.015/ COND=7./DIEL=5)
This card is utilized to describe the homogeneous medium surrounding the structure, If the medium is free space, this card may be omitted. Three options are available and are defined as:
As with INSULATION card state either conductivity or loss tangent.
example:
EXTE(LOSS=.45)
This card is utilized to describe the shape of the wire structure to the program. The user must divide the wire structure into segments of the appropriate length and number each node starting at one. A node is a point where a segment begins or ends. A maximum of four segments can meet at any given node, An isolated wire must contain at least two segments and three nodes. The structure is described by stating the node numbers that each segment connects. The description of a square loop {containing only the four corner points} might appear as:
DESCRIPTION(1-2/2-3/3-4/4-1)
The description of a dipole {containing node points 1 through 5} and reflector {containing node points 6 through 10} might appear as:
DESCRIPTION(1-2/2-3/3-4/4-5/6-7/7-8/8-9/9-10)
{Note that is only necessary to use the first four letters of any control card word so that:
DESC(1-2/2-3/3-4/4-5/6-7/7-8/8-9/9-10)
is equivalent.}
If the description will not fit on one data card continue on the next card as if the previous card were longer, The dipole example might appear as:
DESCRIPTION(1-2/2-3/3-4/4-5((
6-7/7-8/8-9/9-10)
Note that the last two characters on the card to be continued are left parentheses ((
As many cards as necessary may be used. The maximum number of nodes permitted is {originally} fifty {but is now limited by what can be compiled for a given computer. Several compiled versions for the PC are available with maximum nodes ranging from 80 to 1500. The source code can be modified for a different number by changing one PARAMETER statement at the beginning and recompiling.} If a ground plane is present, the maximum number is {originally} twenty-five {or half of whatever the program is compiled to support}.
If a ground plane is present and the structure touches the ground plane, the lowest node numbers MUST be used for the touching nodes. That is, if the structure touches the ground plane at two points, node numbers 1 and 2 MUST be assigned to these nodes. {Additionally in the list of connecting nodes, the node that is on the ground plane must be listed first in the description. Example: if node 2 is on the ground plane and is to be connected to node 4 that is not on the ground plane the nodes must be listed as 2-4 not as 4-2. This is easy to remember as long as the lowest numbered nodes are always specified in the connection pair first. This always works since ground plane nodes must be the lowest numbered nodes.}
{Also note that ground plane nodes cannot be directly connected to each other as they are already on a conducting surface. Nodes on the ground plane can only be connected to each other through at least one other point not on the ground plane. Note: Some structures with multiple connections to the ground plane may be numerically unstable especially if the ground plane is not perfectly conducting.}
{Generally speaking it is a bad idea to have connections to a Ground plane with less than perfect conductivity. A ground stake in or connections to lossy ground (this includes the "GOOD" ground option) cannot be accurately modeled in ASAP since there is presently no provision to compute current interactions across the interface. The program will run these kinds of geometries but the answers will be suspect. Large deviations in impedance (including negative real parts) and erroneous efficiencies can result. }
{ The order in which points are jointed together to form segments using DESCRIPTION or DNODE is important near a FEED. If you have for example 3 nodes 1,2,3; with 2 as the feeding point, 1 is connected to 2 and 2 to 3, you cannot write the DESC-matrix like this: DESC(1-2/3-2) or DESC(2-1/2-3). This produces a current-matrix where all elements are zero. So it seems that the position of the node number in the DESC-matrix fixes the direction of the current. Both segments at the feeding point must have the same direction like (1-2/2-3) or (3-2/2-1). The use of a GENERATOR apparently doesn't have this problem (see the bug area of the quick reference guide for an email about this). }
{ An alternate description input format is available; see "DNODE")
This card is used to state the physical location in rectangular coordinates of each node of the DESCRIPTION CARD . The rectangular grid is in units of meters. If node 1 is located at x1,y1,zl and node 2 at x2,y2,z2 and node 3 at x3,y3,z3,etc,, the GEOMETRY CARD might appear as:
GEOMETRY(xl,yl,zl/x2,y2,z2/x3,y3,z3/....)
{ or
GEOM(xl,yl,zl/x2,y2,z2/x3,y3,z3/....)
}
{ If a ground plane is present and any point(s) of the structure touches (i.e. electrically connected to) the ground plane, they must all be listed first in the geometry listing so they become the lowest numbered nodes. Points that touch the ground are those that have their 'z' coordinate equal to the negative of the HEIGHT value (default=0) as indicated in the GROUND card. Note: Some structures with multiple connections to the ground plane may be numerically unstable especially if the ground plane is not perfectly conducting. Generally speaking it is a bad idea to have connections to a Ground plane with less than perfect conductivity. A ground stake in or connections to lossy ground (this includes the "GOOD" ground option) cannot be accurately modeled in ASAP since there is presently no provision to compute current interactions across the interface. The program will run these kinds of geometries but the answers will be suspect. Large deviations in impedance including negative real parts and erroneous efficiencies can result. }
As with the DESCRIPTION CARD, continuation cards are permitted.
example:
GEOMETRY(.1,0,.1/-.1,0,.1/-.1,0,-.1/.1,0,-.1)
{An alternate geometry input format is available: see "GXYZ"}
{Note that unlike some other antenna analysis programs joining of wire points is NOT done by making the x,y,z coordinate equal. Every x,y,z point entered into ASAP must be unique. Joining of x,y,z points into wire is done with the DESCRIPTION card or with DNODE}
For antenna analysis the feed point(s) and voltage(s) must be stated. In the aforementioned dipole and reflector example if the feeds were at node 2 with a voltage source of .5 at a {phase} angle of -90 degrees and at node 4 with a voltage source of .5 at an {phase} angle of +90 degrees the FEED CARD might appear as:
FEED(2,.5,-90/4,.5,+90)
The order of the information for each voltage source is node number, magnitude, and phase angle. This order is repeated until all sources are stated. If the source information will not fit on one card, use another card similar to the initial one; that is, repeat the word "FEED", If only one voltage source is applied to the structure, only the node number must be stated. In the dipole example, if the drive is at node 3, the FEED CARD might appear as:
FEED (3)
A default source of one voltage at zero degree phase is assumed. Voltage sources should only be stated for nodes with only two segments. {i.e. it is not possible to put a feed at a point where 3 or 4 wire segments join and it is not possible to put a feed at the end of a wire. Use the GENERATOR card for the case of multiple segments joining at one point}
example:
FEED(2,.5,-90/4,.5,+90)
{ Note: The order in which points are jointed together to form segments using DESCRIPTION or DNODE is important near a FEED. See those sections for more information. }
{ Note: See alsoGENERATOR card }
This card is used to describe the loads to be placed at various locations on the structure. The format for this card is similar to that of the FEED CARD, that is, the word "LOAD" is used in the place of "FEED". The order of the information on the card is the same. Since this card is frequency dependent, it must be changed if the frequency of operation is changed. No default parameters are available. The structure is assumed unloaded unless this card is used. Once the structure is loaded, it will remain loaded for the remainder of the data block series. To unload the structure the following card may be used:
LOAD (-1)
example:
LOAD(1,120,-45/3,120,+45)
{Note: see also IMPEDANCE card}
This card is used to request output data. Most of the output is in tabular form. More than one OUTPUT CARD is permitted per data block, but not for the same type of output. If only the antenna input impedance, antenna efficiency, or time-average power input is of interest, no OUTPUT CARD is necessary. These parameters are automatically printed if a FEED CARD or GENERATOR CARD is utilized. One or more of the following options may be used to request the various outputs available.
This option gives the components of the electric field intensity in the far field as phi and theta varies between limits specified in {default} one degree divisions.
This option gives the absorption, scattering, and extinction cross sections, and the complex elements of the polarization scattering matrix for an incident plane wave illuminating the structure from the spherical direction of phi, theta as both vary between limits specified in {default} one degree divisions.
This option gives echo area and the complex elements of the polarization scattering matrix for an incident plane wave illuminating the structure from the spherical direction phi, theta final of the backscattering output option, reradiated in the phi, theta direction as both vary between limits specified in {default} one degree divisions. A bistatic output request must be accompanied with a backscattering request in the same data block.
{Warning!: this can generate massive amounts of output is too large an angle range is used for incident and observation.}
This option will cause any of the above output options to be stepped at a different interval size. That is, if one of the above options is to be stepped at ten degrees intervals, use this option. This option overrides the one degree stepping. {Intervals less than one degree may be used. If a PLOT card is used in the same block will cause the degree steps to revert to one degree.}
{NOTE: The phi and theta directions are not those of the normal mathematical spherical coordinate systems. Phi is the angle measured from the x-axis in the x-y plane with the positive angle toward the y-axis. Theta is the angle measured from the z-axis; it is positive in the direction of the phi angle.}
This option gives the currents on the structure which are produced by the feed/generator voltages and/or the incident plane wave of the backscattering request.
or
This option gives the value of electric field components in the near field for the antenna at the point or points specified.
{ There is now a new key word NEAR at the top level not associated with the OUTPUT card that uses a list input. }
examples {of the OUTPUT card}:
OUTPUT(FARF=45,50,25,50)
{
OUTPUT(FARF=45,50,25,50/NEAR=(1.1,1.8,2.6/3.5,6.7,2.67/23.897,1,34.3))
OUTPUT(CURRENT/FARF=45,50,25,50)
}
This card will produce normalized polar plots in the specified plane for the stated option. The plane is specified by stating either "PHI=__" or "THETA=__ ". The PLOT CARD overrides the limits of the OUTPUT CARD for the same option. {It may also override the STEP=value of the OUTPUT CARD and set it back to one.} If only a normalized pattern is of interest, only a PLOT CARD is necessary. If a table of values and a normalized pattern is desired, both a PLOT CARD and OUTPUT CARD must be used. Only one PLOT CARD is permitted per data block, The following pattern plots are available:
This option will plot the far field intensity for each component of the electric field.
This option will plot the normalized magnitude of each of the elements of the polarization scattering matrix. {'plane' is replaced with either "PHI=__" or "THETA=__ " where the underscore is replaced with the angle of the plane}
This option will plot the normalized magnitude of each of the elements of the polarization scattering matrix produced by the incident plane wave stated by final limits of the backscattering option of the output request. {'plane' is replaced with either "PHI=__" or "THETA=__ " where the underscore is replaced with the angle of the plane}
{NOTE: The phi and theta directions are not those of the normal mathematical spherical coordinate systems. Phi is the angle measured from the x-axis in the x-y plane with the positive angle toward the y-axis. Theta is the angle measured from the z-axis; it is positive in the direction of the phi angle.}
example:
PLOT (FARF/THET=90)
This card is used to describe the ground parameters if a ground plane is present. {The ground plane lies in the x,y (z=0) plane with the structure offset in height in the z direction as described below. } If no ground plane is present, the structure is assumed to be in free space or the homogeneous medium of the EXTERIOR MEDIUM data card.
{Note that if a ground plane is used, the image structure is actually created thereby
doubling the memory usage. Also note that if the structure
touches the ground plane, the lowest node numbers MUST be used for the touching nodes.
That is, if the structure touches the ground plane at two points, node numbers 1
and 2 MUST be assigned to these nodes. A further description of how this rule is applied
is found in the sections on DESCRIPTION and
GEOMETRY}
{Generally speaking it is a bad idea to have connections to a Ground plane with less than perfect conductivity. A ground stake in or connections to lossy ground (this includes the "GOOD" ground option) cannot be accurately modeled in ASAP since there is presently no provision to compute current interactions across the interface. The program will run these kinds of geometries but the answers will be suspect. Large deviations in impedance (including negative real parts) and erroneous efficiencies can result. }
Seven options are available and are defined as:
This option will analyze the structure over a perfect ground plane,
This option will analyze the structure over a good ground plane where the conductivity of the ground is .02 mhos/meter and the relative dielectric constant is 30. {It should be noted that this conductivity is still very poor in comparison to copper which is about 50 megamhos/meter}
This option will analyze the structure over a poor ground plane where the conductivity of the ground is .001 mhos/meter and the relative dielectric constant is 4.
This option will analyze the structure over salt water where the conductivity of the water is 4 mhos/meter and the relative dielectric constant is 80.
This option will analyze the structure with origin of the GEOMETRY card this height {in the z direction} above the ground plane. {In other words, the height card effectively adds the value of HEIGHT to all z components of any structure defined in the GEOMETRY or GXYZ cards} The lowest point of the structure must not lie below the ground plane. It may lie on the ground plane {in which case that node becomes electrically connected to the ground plane}.
This option is used to state the value of conductivity of the ground plane if the default values mentioned above are not utilized.
This option is used to state the relative dielectric constant of the ground plane if the default values mentioned above are not utilized.
example:
GROUND(HEIG=10/COND=.002/DIEL=10)
This card is used to state the number of intervals to be used for calculating the elements of the impedance matrix with Simpson's-rule integration. A large value for the number improves the accuracy at the expense of greater execution time. For most problems a suitable combination of speed and accuracy is obtained with a value of four, the default value. If the rigorous closed-form impedance expressions in terms of the exponential integrals is desired, set this value to zero.
{It highly desirable to change the intervals from the default value when closely spaced wires (in terms of wavelength) such as "transmission lines" or feed structures [e.g. gamma matches, etc.] are present. The rigorous "closed form" expression can - for some geometries - lead to numerical overflow. If this occurs, large values for the Simpson's rule integration (i.e. greater than 20 or so) usually provides accurate results. Stability of the answer can be checked by changing the value and running the problem again.}
{ It should be noted that the INTERVAL is set back to the default value of 4 whenever a new block is started (such as after any CHANGE card even if the only change is to request different outputs from the same problem). }
INTERVAL(value)
example:
INTE(6)
This card is similar to the FEED CARD in use, except that the segment numbers are stated instead of the node numbers. This is useful if three or four segments meet at a node. The positive terminal of the generator is connected to the specified segment such that current is forced in the positive direction. The positive direction of current flow is from the first stated node number of that segment toward the second stated as ordered on the DESCRIPTION {or DNODE} CARD.
example:
GENE(2,.5,-90/4,.5,+90)
This card is similar to the LOAD CARD in use, except that the segment numbers are stated instead of the node numbers. As with the GENERATOR CARD, this is used if three or four segments are connected to a node. The impedance will be connected to the positive terminal of the specified segment. The format of this card is the same as the LOAD CARD.
example:
IMPE(1,120,-45/3,120,+45)
This card at the end of the data block signals the program that the following data cards are changes to the previously read data, for the next run. If a "CHANGE CARD" is used, the outputs must be requested again in the next data block.
{This card when used only retains the structure (wire size, geometry, and connection list) and the frequency. The number for the calculation INTERVAL is reset to the default value. This card is most useful for changing FREQUENCY, LOAD or IMPEDANCE, and requested outputs without having to copy the whole input data set again. However, requesting different outputs may cause recalculation of the whole problem so it is best to request all possible outputs in one block if possible. An END CARD is recommended over a CHANGE CARD if there is to be changes to the structure geometry or connection list especially if there are points touching the ground plane. Failure to observe this precaution can lead to strange (i.e. wrong) results.}
This card signals the program that this is the end of a data block series and to reinitialize data for the next problem. An "END CARD" cannot be used with a "CHANGE CARD". {An END CARD is recommended over a CHANGE CARD if there is to be changes to the structure geometry or connection list especially if there are points touching the ground plane. Failure to observe this precaution can lead to strange (i.e. wrong) results.}
This card signals the program that all of the data cards have been read and to terminate itself when execution is completed. This card must be used as the last card in place of the "END CARD" of the last data block series. "STOP CARD" cannot be used with an "END CARD" in the same data block. {The STOP card should be followed by a blank line to insure that the ASAP input routines know that the last card has been read.}
{Since the program ignores any data after the STOP card, lines following STOP may be used to store data for convenience of editing past and future runs.}
This card indicates the frequency in Megahertz of all signal sources or fields that will be used in the calculation of the problem. The frequency must be in units of Megahertz; no other unit of frequency is available. Decimal values are permitted so any practical frequency range is supported.
This card may be omitted in which case the default value of frequency is 300 MHz. Note that the default value of 300 MHz results in a wavelength of one-meter (in free space) so the geometry can be interpreted directly in terms of wavelength whenever the exterior medium is vacuum or air (i.e. the default medium).
example:
FREQ(1.0275)
(Note: The FREQUENCY card description was inadvertently omitted from the original printed manual) }
{ A Sample Input }
C AN EXAMPLE PROBLEM C C V ANTENNA C WIRE(RADIUS=1M) GEOM(0,-.18,+.18/0,-.09,+.09/0,0,0/0,0.09,.09/0,.18,.18) DESC(1-2/2-3/3-4/4-5) FEED(3) OUTPUT(FARF=45,50,65,80/STEP=5) CHANGE OUTPUT(BIST=45,45,45,45/BACK=0,0,10,12) OUTPUT(CURRENT) CHANGE C C CHANGE STRUCTURE SHAPE TO DIPOLE C GEOM(0,-.25,0/0,-.125,0/0,0,0/0,.125,0/0,.25,0) PLOT(FARF/PHI=90) GROUND(HEIGHT=.25/GOOD) STOP
{ This input file can be copied from this screen into a plain ASCII editor using cut and paste operation but is also available as umexin.txt. The output that is generated from this data file can be found in the file umexout.txt. It will be necessary to use a editor/viewing program that allows long lines without wrapping as the output is formatted for a wide line printer. A web-browser program may work fine for this. }
{More detailed examples are available on the Examples page.}
{GXYZ and DNODE alternatives to GEOM and DESCR.
There are some "improvements" in the way that geometry points and connection descriptions can be made that are not in the original manual. The original input format used the GEOM and DESCR cards. The modifications made to the program allow input using GXYZ and DNODE cards as well. When using GXYZ and DNODE all the normal requirements for the use of GEOM and DESCR cards apply (such as the rules regarding the nodes touching the ground plane must be the first points listed so that they are the lowest numbered nodes and the rules for keeping the segment order proper near a FEED.) Also be sure to avoid connections to lossy ground planes as described in the GEOM, DESCR and GROUND cards.
C TEST DIPOLE USING ORIGINAL FORM OF INPUT WIRE(RADIUS=.01) GROUND(HEIGHT=10/POOR) GEOM(0,0,0/1,0,0/2,0,0/3,0,0/4,0,0) DESCR(1-2/2-3/3-4/4-5) FEED(3) FREQ(37) PLOT(FARF/PHI=0) OUTPUT(FARF=0,0,0,90) STOP
The following example produces the same results as the above example. The new data format allows easier insertion of pre-processor generated data in the form of X Y Z coordinates. The GXYZ and the DNODE lists are closed by placing XXXX at the end of the list of values.
C TEST DIPOLE USING NEW DATA INPUT FORMAT WIRE(RADIUS=.01) GROUND(HEIGHT=10/POOR) GXYZ 0 0.5 0.1 1 0.4 0.2 2 0.3 0.3 3 0.2 0.4 4.0 0.1 0.5 XXXX DNODE 1 2 2 3 3 4 4 5 XXXX FEED(3) FREQ(37) PLOT(FARF/THETA=90) STOP
Note that only spaces are used between the individual X Y Z component lists of GXYZ. Commas are not used between the X Y Z coordinates and the number of spaces used can be chosen to make the list easy to read if desired. If the number is a whole number then the decimal point is optional. Note that the letter extensions U, M, or K to indicate engineering multipliers will not work with the new X Y Z list inputs for GXZY or the new NEAR X Y Z lists.
The GXYZ card uses a regular free formatted input READ so notes may be placed after each geometry point without effecting the input data stream. This is mainly useful in allowing a pre-processor geometry generator program to show the user the numbering scheme used to allow manual modification of the connection description. Also because of the free format input, any amount of whitespace (spaces, tabs) can be used between the GXYZ or DNODE data numbers as long as everything fits on the same line. This allows direct copying of points generated in other programs (such a spreadsheets that are used as a geometry setup programs) into the input file.
C TEST DIPOLE USING NEW DATA INPUT FORMAT WIRE(RADIUS=.01) GROUND(HEIGHT=10/POOR) GXYZ 0 0 0 / Notes may be placed 1 0 0 / after each of the input wire 2 0 0 / geometry points when GXYZ is used by using 3 0 0 / slashes to delineate end of the FORTRAN READ. 4 0 0 / Useful for pre-processor placed notes. XXXX DNODE 1 2 /Notes may be placed 2 3 /After the connector 3 4 /lists also 4 5 XXXX FEED(3) FREQ(37) PLOT(FARF/THETA=90) STOP
The order in which points are jointed together to form segments using DESCRIPTION or DNODE is important near a FEED. If you have for example 3 nodes 1,2,3; with 2 as the feeding point, 1 is connected to 2 and 2 to 3, you cannot write the DNODE list like this:
1 2 3 2
or
2 1 2 3
This produces a current-matrix where all elements are zero. So it seems that the position of the node number in the DNODE-matrix fixes the direction of the current. Both segments at the feeding point must have the same direction like:
1 2 2 3
or
3 2 2 1
The use of a GENERATOR apparently doesn't have this problem (see the bug area of the quick reference guide for an email about this).
** end of DNODE and GXYZ description }
{NEAR list input alternatives to the NEAR keyword in the OUTPUT card
Starting with Version 3.2 there is a new way of entering near-field point lists. This original way is to use the NEAR keyword in the OUTPUT card but this limits the list of points to what can fit on one line. This original way is still available but a new improved way using lists is now available
The new way starting in version 3.2 uses the new key word: NEAR. This is a new Keyword that works like GXYZ where you give a list of points then end the list with XXXX
NEAR 0.0 0.1 0.2 1.3 5.3 4.0 2.0 3.4 5.9 XXXX
The points are listed as geometric coordinates of X Y and Z. Note that only spaces are used between the individual X Y Z component lists of GXYZ. Commas are not used between the X Y Z coordinates and the number of spaces used can be chosen to make the list easy to read if desired. If the number is a whole number then the decimal point is optional. Note that the letter extensions U, M, or K to indicate engineering multipliers will not work with the new X Y Z list inputs for GXZY or NEAR.
The number of points is limited only by the memory for which the particular compilation was set by the PARAMETER statement at the beginning of the program.
Notes can be placed after each of the near field points by using a forward slash after the last number.
NEAR 0.0 0.1 0.2 0 0 0 / Notes may be placed 1 0 0 / after each of the input points 2 0 0 / when NEAR is used by using 3 0 0 / slashes to delineate end of the FORTRAN READ. 4 0 0 1.3 5.3 4.0 / They are optional 2.0 3.4 5.9 XXXX
Here is an example input file using the original NEAR keyword in the OUTPUT card.
C TEST DIPOLE USING NEW DATA INPUT FORMAT FOR GEOMETRY C BUT OLD FORMAT FOR NEARFIELD DATA C WIRE(RADIUS=.01) GROUND(HEIGHT=10/POOR) GXYZ 0 0.5 0.1 1 0.4 0.2 2 0.3 0.3 XXXX DNODE 1 2 2 3 XXXX FEED(2) FREQ(75) PLOT(FARF/THETA=90) OUTPUT(FARF=45,50,25,50/NEAR=(1.1,1.8,2.6/3.5,6.7,2.67/23.897,1,34.3)) STOP
Here is an example input file with the new NEAR field point listing using the same nearfield point list.
C TEST DIPOLE USING NEW DATA INPUT FORMAT FOR GEOMETRY C WITH NEW FORMAT FOR NEAR FIELD DATA C WIRE(RADIUS=.01) GROUND(HEIGHT=10/POOR) GXYZ 0 0.5 0.1 1 0.4 0.2 2 0.3 0.3 XXXX DNODE 1 2 2 3 XXXX FEED(2) FREQ(75) PLOT(FARF/THETA=90) OUTPUT(FARF=45,50,25,50) NEAR 1.1 1.8 2.6 3.5 6.7 2.67 / The irregular spacing in this example 23.897 1 34.3 / illustrates the free format that can be used XXXX STOP}
See also the quick reference for the user's guide which contains tips and techniques for using the code and avoiding pitfalls.
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Last modified on: 3 Nov 2007