necpp

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README

go-libnecpp

GoDoc

A Go wrapper around libnecpp, which is a C library for nec++, which is a C++ rewrite of nec2c, which is itself a C rewrite/translation of the original FORTRAN code for NEC2, an antenna modelling package.

Installation

This package requires nec++ to be installed. On Linux, it's often found in the distribution packages. Otherwise, and on other Unix-y OSes, it should build per the instructions in the necpp library.

Installing nec++ on Mac OS X is likely to be more difficult, because clang gets unhappy about some of the Fortranisms still creeping around in the code. Even when that's cleared up by applying a couple of the pull requests on the github page, you still need to configure nec++ with the --without-lapack option. A procudure for installing necpp smoothly is in the works.

This package should be able to build on Windows, assuming you've been able to build nec++ with the instructions for Windows on the github page.

Documentation

See the godocs for more detailed documentation for go-libnecpp.

Also very relevant:

LICENSE

This library is licensed under the GPL (since the original libnecpp library is). Details can be found in the LICENSE file in this repository.

AUTHOR

The golang libnecpp wrapper was written by Jeremy Bingham (jeremy@goiardi.gl).

Nec++ was written by Tim Molteno tim@physics.otago.ac.nz.

Nec2c (the C port which nec++ was based on) was done by by Neoklis Kyriazis.

Documentation

Overview

Package necpp is a Go wrapper around libnecpp, which is a C library for nec++, which is a C++ rewrite of nec2c, which is itself a C rewrite/translation of the original FORTRAN code for NEC2, an antenna modelling package.

Installation

This package requires nec++ to be installed. On Linux, it's often found in the distribution packages. Otherwise, and on other Unix-y OSes, it should build per the instructions in the necpp library.

Installing nec++ on Mac OS X is likely to be more difficult, because clang gets unhappy about some of the Fortranisms still creeping around in the code. Even when that's cleared up by applying a couple of the pull requests on the github page, you still need to configure nec++ with the `--without-lapack` option. A procudure for installing necpp smoothly is in the works.

This package should be able to build on Windows, assuming you've been able to build nec++ with the instructions for Windows on the github page.

After that's installed, go-libnecpp can be installed with the usual 'go get'.

Groups of Methods

The methods in this library can be grouped into a few general groups - antenna geometry, antenna environment, simulation output, output analysis, and initialization/cleanup type methods. While they are grouped together in the source, godoc rearranges them into alphabetical order.

The groupings of methods in this library are:

Initialization and Cleanup

New(), Delete()

Antenna Geometry

Wire(), SpCard(), ScCard(), GmCard(), GxCard(), GeometryComplete()

Antenna Environment

MediumParameters(), GnCard(), FrCard(), EkCard(), LdCard(), ExCard(), ExcitationVoltage(), ExcitationCurrent(), ExcitationPlanewave(), TlCard(), NtCard(), XqCard(), GdCard()

Simulation Output

RpCard(), PtCard(), PqCard(), KhCard(), NeCard(), NhCard(), CpCard(), PlCard()

Output Analysis

Gain(), GainMax(), GainMin(), GainMean(), GainRhcpMax(), GainRhcpMin(), GainRhcpMean(), GainRhcpSd(), GainLhcpMax(), GainLhcpMin(), GainLhcpMean(), GainLhcpSd()

Documentation

• nec++'s github page can be found at https://github.com/tmolteno/necpp/.

• The nec++ documentation at http://tmolteno.github.io/necpp/

• Neoklis Kyriazis' website at http://www.qsl.net/5b4az/, which includes the homepage for nec2c.

• The user's manual for NEC2 at http://www.nec2.org/part_3/toc.html. This manual may make some of the more obscure portions of the documentation taken from nec++ more clear.

The godocs for this package have brought over the documentation for libnecpp.h from nec++, adapted somewhat to fit the golang wrapper functions better. Some functions were not documented there, and have not been documented here yet either. The NEC2 user manual may shed light on what a particular method does and what values should be used with it. As time permits, the missing method documentation from the NEC2 user manual will be added to the documentation here, and some of the variables will likely get more meaningful names as their functions become more clear.

Being a Go wrapper around a C interface for a C++ rewrite of a C rewrite of a FORTRAN program, there's some weirdness and not entirely Go customs compliant bits creeping around.

Index

Constants

View Source 
const GainErrno float64 = -999.0

GainErrno is the number returned by the Gain* functions when no radiation pattern was previously requested.

Variables

View Source 
var ErrNoPatternRequested = errors.New("no radiation pattern previously requested")

Functions

This section is empty.

Types

type Excitation 

type Excitation int

Excitation sets the type of excitation for ExCard 

const (
	VoltageApplied    Excitation = iota // voltage source (applied-E-field source)
	IncidentLinear                      // incident plane wave, linear polarization.
	IncidentRightHand                   // incident plane wave, right-hand (thumb along the incident k vector) elliptic polarization.
	IncidentLeftHand                    // incident plane wave, left-hand elliptic polarization.
	Elementary                          // elementary current source
	VoltageSlope                        // voltage source (current-slope-discontinuity)
)

type ExecutionOption 

type ExecutionOption int

ExecutionOption control the generation of radiation patterns with XqCard()

Options for radiation patterns:

• NoPattern - no patterns requested (the normal case).

• XZPlane - generates a pattern cut in the XZ plane, i.e., phi = 0 degrees and theta varies from 0 degrees to 90 degrees in 1 degree steps.

• YZPlane - generates a pattern cut in the YZ plane, i.e., phi = 90 degrees theta varies from 0 degrees to 90 degrees in 1 degree steps.

• BothPlane - generates both of the cuts described for XZPlane and YZPlane. 

const (
	NoPattern ExecutionOption = iota
	XZPlane
	YZPlane
	BothPlane
)

type FrequencyRange 

type FrequencyRange int

FrequencyRange is used to set the type of frequency range for FR cards. 

const (
	Linear      FrequencyRange = iota // a linear range
	Logarithmic                       // a logarithmic range
)

type GeoGroundPlaneFlag 

type GeoGroundPlaneFlag int

GeoGroundPlaneFlag is used to indicate the type of ground plane to use with the antenna when indicating the geometry is complete.

The types of ground plane to use are:

• NoGroundPlane - no ground plane is present. (Fairly self-explanatory.)

• CurrentExpansionModified - Structure symmetry is modified as required, and the current expansion is modified so that the currents and segments touching the ground (x, Y plane) are interpolated to their images below the ground (charge at base is zero)

• CurrentExpansionUnmodified - indicates a ground is present. Structure symmetry is modified as required. Current expansion, however, is not modified, Thus, currents on segments touching the ground will go to zero at the ground. 

const (
	CurrentExpansionUnmodified GeoGroundPlaneFlag = iota - 1
	NoGroundPlane
	CurrentExpansionModified
	MooMoo
)

type GroundTypeFlag 

type GroundTypeFlag int

GroundTypeFlag indicates the general type of ground for the antenna.

The flags for ground types are:

• Nullified - Nullifies ground parameters previously used and sets free-space condition. The remainder of the parameters are ignored in this case.

• Finite - Finite ground, reflection coefficient approximation.

• Perfect - Perfectly conducting ground.

• FiniteSomNorton - Finite ground, Sommerfeld/Norton method. 

const (
	Nullified GroundTypeFlag = iota - 1
	Finite
	Perfect
	FiniteSomNorton
)

type NecppCtx 

type NecppCtx struct {
	// contains filtered or unexported fields
}

NecppCtx is the nec context, and contains the libnecpp nec_context struct within itself.

func New 

func New() (*NecppCtx, error)

New creates a new NEC context object, which contains the nec_context struct pointer from libnecpp. After it's done being used, call Delete() to free the struct.

func (*NecppCtx) CpCard 

func (n *NecppCtx) CpCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int) error

CpCard makes a CP Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) Delete 

func (n *NecppCtx) Delete() error

Delete frees the nec_context struct. Call this after you're finished simulating the antenna.

func (*NecppCtx) EkCard 

func (n *NecppCtx) EkCard(itmp1 WireKernel) error

EkCard controls the use of the external thin-wire kernel approximation.

func (*NecppCtx) ExCard 

func (n *NecppCtx) ExCard(extype Excitation, i2 int, i3 int, i4 int, tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

ExCard applies a source of excitation to the antenna, making an EX card.

Parameters: 

extype - one of the Excitation constants - VoltageApplied,
 	IncidentLinear, IncidentLeftHand, IncidentRightHand, Elementary,
	or VoltageSlope
i2 - Tag number the source segment. This tag number along with the
number to be given in (i3), which identifies the position of the
segment in a set of equal tag numbers, uniquely definer the source
segment. A 0 in field i2 implies that the Source segment will be
identified by using the absolute segment number in the next field (i3).
i3 - Equal to m, specifies the mth segment of the set of segments whose
tag numbers are equal to the number set by the previous parameter. If
the previous parameter is zero, the number in (i3) must be the absolute
segment number of the source.
i4 -  Meaning Depends on the extype parameter. See http://www.nec2.org/part_3/cards/ex.html

The meaning of the floating point parameter depends on the excitation type. See http://www.nec2.org/part_3/cards/ex.html for more details.

Simpler versions of the function are provided for common uses. These are ExcitationVoltage, ExcitationCurrent, and ExcitationPlanewave.

func (*NecppCtx) ExcitationCurrent 

func (n *NecppCtx) ExcitationCurrent(x float64, y float64, z float64, a float64, beta float64, moment float64) error

ExcitationCurrent makes a current source excitation for the antenna. It is one of the simpler versions of ExCard().

Parameters: 

x - X position in meters.
y - Y position in meters.
z - Z position in meters.
a - a in degrees. a is the angle the current source makes with the XY
plane as illustrated on figure 15.
beta - beta in degrees. beta is the angle the projection of the current
source on the XY plane makes with the X axis.
moment - "Current moment" of the source. This parameter is equal to the
product Il in amp meters.

Only one incident plane wave or one elementary current source is allowed at a time. Also plane-wave or current-source excitation is not allowed with voltage sources. If the excitation types are mixed, the program will use the last excitation type encountered.

func (*NecppCtx) ExcitationPlanewave 

func (n *NecppCtx) ExcitationPlanewave(nTheta int, nPhi int, theta float64, phi float64, eta float64, dTheta float64, dPhi float64, polRatio float64) error

ExcitationPlanewave makes a linear polarized planewave excitation source. It is one of the simpler versions of ExCard().

Parameters: 

nTheta - Number of theta angles desired for the incident plane wave .
nPhi - Number of phi angles desired for the incident plane wave.
theta - Theta in degrees. Theta 19 defined in standard spherical coordinates as illustrated
phi - Phi in degrees. Phi is the standard spherical angle defined lned in the XY plane.
eta - Eta in degrees. Eta is the polarization angle defined as the angle
between the theta unit vector and the direction of the electric field
for linear polarization or the major ellipse axis for elliptical
polarization.
dTheta - Theta angle stepping increment in degrees.
dPhi - Phi angle stepping increment in degrees.
polRatio - Ratio of minor axis to major axis for elliptic polarization
(major axis field strength - 1 V/m).

Only one incident plane wave or one elementary current source is allowed at a time. Also plane-wave or current-source excitation is not allowed with voltage sources. If the excitation types are mixed, the program will use the last excitation type encountered.

func (*NecppCtx) ExcitationVoltage 

func (n *NecppCtx) ExcitationVoltage(tag int, segment int, voltageExcitation complex128) error

ExcitationVoltage makes a voltage source excitation source for the antenna. It is one of the simpler versions of ExCard().

Parameters: 

tag - Tag number of the source segment. This tag number along with the
number to be given in (segment), which identifies the position of the
segment in a set of equal tag numbers, uniquely definer the source
segment. A zero in field (tag) implies that the Source segment will be
identified by using the absolute segment number in the next field
(segment).
segment - Equal to m, specifies the mth segment of the set of segments
whose tag numbers are equal to the number
set by the previous parameter. If the previous parameter is zero, the
number in (segment) must be the absolute segment number of the source.
voltageExcitation - a complex128 number representing the voltage
excitation.

Only one incident plane wave or one elementary current source is allowed at a time. Also plane-wave or current-source excitation is not allowed with voltage sources. If the excitation types are mixed, the program will use the last excitation type encountered.

func (*NecppCtx) FrCard 

func (n *NecppCtx) FrCard(inIfrq FrequencyRange, inNfrq int, inFreqMhz float64, inDelFreq float64) error

FrCard makes a FR Card for frequency ranges.

Parameters: 

inIfrq - a FrequencyRange constant, Linear or Logarithmic, for linear or
logarithmic range of frequencies.
inNfreq - the number of frequencies
inFreqMhz - the starting frequency in MHz.
inDelFreq - the frequency step in MHz (for inIfreq == Linear)

func (*NecppCtx) Gain 

func (n *NecppCtx) Gain(freqIndex int, thetaIndex int, phiIndex int) (float64, error)

Gain gets the gain from a radiation pattern.

Parameters: 

freqIndex - The rp_card frequency index. If this parameter is 0, then
the first simulation results are used. Subsequent simulations will store
their results at higher indices.
thetaIndex - The theta index (starting at zero) of the radiation pattern
phiIndex - The phi index (starting at zero) of the radiation pattern

This method returns the gain in db, or -999.0 and an error if no radiation pattern had been previously requested.

This function requires a previous RpCard() method to have been called (with the gain normalization set to TotalNormalized).

func (*NecppCtx) GainLhcpMax 

func (n *NecppCtx) GainLhcpMax(freqIndex int) (float64, error)

func (*NecppCtx) GainLhcpMean 

func (n *NecppCtx) GainLhcpMean(freqIndex int) (float64, error)

func (*NecppCtx) GainLhcpMin 

func (n *NecppCtx) GainLhcpMin(freqIndex int) (float64, error)

func (*NecppCtx) GainLhcpSd 

func (n *NecppCtx) GainLhcpSd(freqIndex int) (float64, error)

func (*NecppCtx) GainMax 

func (n *NecppCtx) GainMax(freqIndex int) (float64, error)

GainMax gets the maximum gain from a radiation pattern.

Parameters: 

freqIndex - The rp_card frequency index. If this parameter is 0, then
the first simulation results are used. Subsequent simulations will store
their results at higher indices.

This method returns the gain in db, or -999.0 and an error if no radiation pattern had been previously requested.

This function requires a previous RpCard() method to have been called (with the gain normalization set to TotalNormalized).

func (*NecppCtx) GainMean 

func (n *NecppCtx) GainMean(freqIndex int) (float64, error)

GainMean gets the mean gain from a radiation pattern.

Parameters: 

freqIndex - The rp_card frequency index. If this parameter is 0, then
the first simulation results are used. Subsequent simulations will store
their results at higher indices.

This method returns the gain in db, or -999.0 and an error if no radiation pattern had been previously requested.

This function requires a previous RpCard() method to have been called (with the gain normalization set to TotalNormalized).

func (*NecppCtx) GainMin 

func (n *NecppCtx) GainMin(freqIndex int) (float64, error)

GainMin gets the minimum gain from a radiation pattern.

Parameters: 

freqIndex - The rp_card frequency index. If this parameter is 0, then
the first simulation results are used. Subsequent simulations will store
their results at higher indices.

This method returns the gain in db, or -999.0 and an error if no radiation pattern had been previously requested.

This function requires a previous RpCard() method to have been called (with the gain normalization set to TotalNormalized).

func (*NecppCtx) GainRhcpMax 

func (n *NecppCtx) GainRhcpMax(freqIndex int) (float64, error)

func (*NecppCtx) GainRhcpMean 

func (n *NecppCtx) GainRhcpMean(freqIndex int) (float64, error)

func (*NecppCtx) GainRhcpMin 

func (n *NecppCtx) GainRhcpMin(freqIndex int) (float64, error)

func (*NecppCtx) GainRhcpSd 

func (n *NecppCtx) GainRhcpSd(freqIndex int) (float64, error)

func (*NecppCtx) GainSd 

func (n *NecppCtx) GainSd(freqIndex int) (float64, error)

GainSd gets the standard deviation of the gain from a radiation pattern.

Parameters: 

freqIndex - The rp_card frequency index. If this parameter is 0, then
the first simulation results are used. Subsequent simulations will store
their results at higher indices.

This method returns the gain in db, or -999.0 and an error if no radiation pattern had been previously requested.

This function requires a previous RpCard() method to have been called (with the gain normalization set to TotalNormalized).

func (*NecppCtx) GdCard 

func (n *NecppCtx) GdCard(tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64) error

GdCard, presumably, makes a GD card.

func (*NecppCtx) GeometryComplete 

func (n *NecppCtx) GeometryComplete(gpflag GeoGroundPlaneFlag) error

GeometryComplete indicates the antenna geometry is complete - makes a GE card. See GeoGroundPlaneFlag for details on that parameter.

func (*NecppCtx) GmCard 

func (n *NecppCtx) GmCard(itsi int, nrpt int, rox float64, roy float64, roz float64, xs float64, ys float64, zs float64, its int) error

GmCard makes a GM card for Coordinate Transformation

Parameters: 

	 itsi  Tag number increment.
	 nprt  The number of new Structures to be generated
	 rox   Angle in degrees through which the structure is rotated about
            the X-axis.  A positive angle causes a right-hand rotation.
	 roy   Angle of rotation about Y-axis.
	 roz   Angle of rotation about Z-axis.
	 xs    X, Y. Z components of vector by which
	 ys    structure is translated with respect to
	 zs    the coordinate system.
	 its   This number is input as a decimal number but is rounded
            to an integer before use.  Tag numbers are searched sequentially
            until a segment having a tag of this segment through the end of
            the sequence of segments is moved by the card.  If ITS is zero
            the entire structure is moved.

func (*NecppCtx) GnCard 

func (n *NecppCtx) GnCard(iperf GroundTypeFlag, nradl int, epse float64, sig float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

GnCard makes a ground card.

Examples (TODO: check these examples out more - not sure if they're quite right)

  1. Infinite ground plane n.GnCard(Perfect, 0, 0, 0, 0, 0, 0, 0)
  2. Radial Wire Ground Plane (4 wires, 2 meters long, 5mm in radius) n.GnCard(Perfect, 4, 0.0, 0.0, 2.0, 0.005, 0.0, 0.0)

Parameters (some - not all were detailed in the upstream documentation) 

iperf - Ground type flag. See the GroundTypeFlag constants for what
goes here.
nradl - Number of radial wires in the ground screen approximation, O implies no ground screen.
epse - Relative dielectric constant for ground in the vicinity of the
antenna. Zero in the case of perfect ground.
sig - Conductivity in mhos/meter of the ground in the vicinity of the
antenna. Use zero in the case of a perfect ground. If SIG is input as a
negative number, the complex dielectric constant Ec = Er -j sigma/omega
epsilon is set to EPSR - |SIG|.

func (*NecppCtx) GxCard 

func (n *NecppCtx) GxCard(i1 int, i2 int) error

GxCard creates a GX card for Reflection in coordinate Planes. 

 Parameters:
	i1 - Tag number increment.
   	i2 - This integer is divided into three independent digits, in
        columns 8, 9, and 10 of the card, which control reflection
        in the three orthogonal coordinate planes.  A one in column
        8 causes reflection along the X-axis (reflection in Y, Z
        plane); a one in column 9 causes reflection along the Y-axis;
        and a one in column 10 causes reflection along the Z axis.
        A zero or blank in any of these columns causes the corres-
        ponding reflection to be skipped.

Any combination of reflections along the X, Y and Z axes may be used. For example, 101 for i2 will cause reflection along axes X and Z, and 111 will cause reflection along axes X, Y and Z. When combinations of reflections are requested, the reflections are done in reverse alphabetical order. That is, if a structure is generated in a single octant of space and a GX card is then read with i2 equal to 111, the structure is first reflected along the Z-axis; the structure and its image are then reflected along the Y-axis; and, finally, these four structures are reflected along the X-axis to fill all octants. This order determines the position of a segment in the sequence and, hence, the absolute segment numbers.

The tag increment i1 is used to avoid duplication of tag numbers in the image segments. All valid tags on the original structure are incremented by i1 on the image. When combinations of reflections are employed, the tag increment is doubled after each reflection. Thus, a tag increment greater than or equal to the largest tag an the original structure will ensure that no duplicate tags are generated. For example, if tags from 1 to 100 are used on the original structure with i2 equal to 011 and a tag increment of 100, the first reflection, along the Z-axis, will produce tags from 101 to 200; and the second reflection, along the Y-axis, will produce tags rom 201 to 400, as a result of the increment being doubled to 200.

func (*NecppCtx) Impedance 

func (n *NecppCtx) Impedance(freqIndex int) (complex128, error)

Impedance gets the impedance of the antenna. It returns a complex128 number, and takes the place of two separate C library functions that returned the real and imaginary portions of the impedance, respectively.

func (*NecppCtx) KhCard 

func (n *NecppCtx) KhCard(tmp1 float64) error

KhCard makes a KH Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) LdCard 

func (n *NecppCtx) LdCard(ldtype int, ldtag int, ldtagf int, ldtagt int, tmp1 float64, tmp2 float64, tmp3 float64) error

LdCard - loading.

Parameters: 

ldtyp - Type of loading (5 = segment conductivity)
ldtag - Tag (zero for absolute segment numbers, or in conjunction with 0 for next parameter, for all segments)
ldtagf - Equal to m specifies the mth segment of the set of segments
whose tag numbers equal the tag number specified in the previous
parameter. If the previous parameter (LDTAG) is zero, LDTAGF then
specifies an absolute segment number. If both LDTAG and LDTAGF are zero,
all segments will be loaded.
ldtagt - Equal to n specifies the nth segment of the set of segments
whose tag numbers equal the tag number specified in the parameter LDTAG.
This parameter must be greater than or equal to	the previous parameter.
The loading specified is applied to each of the	mth through nth segments
of the set of segments having tags equal to LDTAG. Again if LDTAG is
zero, these parameters refer to absolute segment numbers. If LDTAGT is
left blank, it is set equal to the previous parameter (LDTAGF).
tmp1 Resistance in Ohms, OR (A) Ohms per meter, OR (B) Resistance. OR
(C) Conductivity (ldtyp=5)
tmp2 IND., HENRY, OR (A) HY/LENGTH OR (B) REACT. OR (C) Set to 0.0
tmp3 CAP,. FARAD, OR (A,B) BLANK (set to 0.0)

func (*NecppCtx) MediumParameters 

func (n *NecppCtx) MediumParameters(permittivity float64, permeability float64) error

MediumParameters sets the permittivity and permeability of the medium.

Parameters: 

permittivity - The electric permittivity of the medium (in farads per
	meter)
permeability - The magnetic permeability of the medium (in henries per
	meter)

func (*NecppCtx) NeCard 

func (n *NecppCtx) NeCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int, tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

NeCard makes a NE Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) NhCard 

func (n *NecppCtx) NhCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int, tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

NhCard makes a NH Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) NtCard 

func (n *NecppCtx) NtCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int, tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

NtCard, presumably, makes an NEC2 NT Card.

func (*NecppCtx) PlCard 

func (n *NecppCtx) PlCard(ploutputFilename string, itmp1 int, itmp2 int, itmp3 int, itmp4 int) error

PlCard makes a PL Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) PqCard 

func (n *NecppCtx) PqCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int) error

PqCard makes a PQ Card. Needs documentation from the NEC2 user manual.

func (*NecppCtx) PtCard 

func (n *NecppCtx) PtCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int) error

PtCard makes a PT Card for printing of currents. This methods documentation needs to be checked against the NEC2 user manual before renaming these variables and making a new type for a flag. This is what was in libnecpp.h.

IPTFLG Print control flag, specifies the type of format used in printing segment currents. The options are: 

-2 - all currents printed. This it a default value for the program if the card is Omitted.
-1 - suppress printing of all wire segment currents.
0 - current printing will be limited to the segments specified by the next three parameters.
1 - currents are printed by using a format designed for a receiving pattern (refer to output section in this manual Only currents for the segments specified by the next three parameters are printed.
2 - same as for 1 above; in addition, however, the current for one Segment will Cue normalized to its maximum, ant the normalized values along with the relative strength in tB will be printed in a table. If the currents for more than one segment are being printed, only currents from the last segment in the group appear in the normalized table.
3 - only normalized currents from one segment are printed for the receiving pattern case.

IPTAG - Tag number of the segments for which currents will be printed.

IPTAGF - Equal to m, specifies the mth segment of the set of segments having the tag numbers of IPTAG, at which printing of currents starts. If IPTAG is zero or blank, then IPTAGF refers to an absolute segment number. If IPTAGF is blank, the current is printed for all segments.

IPTAGT - Equal to n specifies the nth segment of the set of segments having tag numbers of IPTAG. Currents are printed for segments having tag number IPTAG starting at the m th segment in the set and ending at the nth segment. If IPTAG is zero or blank, then IPTAGF and IPTAGT refer to absoulte segment numbers. In IPTAGT is left blank, it is set to IPTAGF.

func (*NecppCtx) RpCard 

func (n *NecppCtx) RpCard(calcMode RpCalcMode, nTheta int, nPhi int, outputFormat RpOutputFormat, normalization RpNormalization, d RpGain, a RpAveraging, theta0 float64, phi0 float64, deltaTheta float64, deltaPhi float64, radialDistance float64, gainNorm float64) error

RpCard calculates the radiation patterns for the antenna.

Parameters: 

calcMode - a RpCalcMode flag. See the RpCalcMode constants for those
definitions.
nTheta - the number of theta angles
nPhi - the number of phi angles
outputFormat - a RpOutputFormat flag. See the RpOutputFormat constants
for those definitions.
normalization - a RpNormalization flag. See the RpNormalization
constants for those definitions.
d - a RpGain flag, either PowerGain or DirectiveGain.
a - a RpAveraging flag. See the RpAveraging constants for those
definitions.
theta0 - Initial theta angle in degrees (initial z coordinate in meters
if calc_mode = 1).
phi0 - Initial phi angle in degrees.
deltaTheta - Increment for theta in degrees (increment for z in meters
if calc_mode = 1).
deltaPhi - Increment for phi in degrees.
radialDistance - Radial distance (R) of field point from the origin in
meters. radial_distance is optional. If it is zero, the radiated
electric field will have the factor exp(-jkR)/R omitted. If a value of
R is specified, it should represent a point in the far-field region
since near components of the field cannot be obtained with an RP card.
(If calc_mode = 1, then radial_distance represents the cylindrical
coordinate phi in meters and is not optional. It must be greater than
about one wavelength.)
gainNorm - Determines the gain normalization factor if normalization has
been requested in the normalization parameter. If gain_norm is zero,
the gain will be normalized to its maximum value. If gain_norm is not
zero, the gain wi11 be normalized to the value of gain_norm.

The field point is specified in spherical coordinates (R, sigma, theta), except when the surface wave is computed. For computing the surface wave field (calcMode = l), cylindrical coordinates (phi, theta, z) are used to accurately define points near the ground plane at large radial distances.

The RpCard() function allows automatic stepping of the field point to compute the field over a region about the antenna at uniformly spaced points.

The integers nTheta and nPhi, and floating point numbers theta0, phi0, deltaTheta, deltaPhi, radialDistance, and gainNorm control the field-point stepping.

The RpCard() method will cause the interaction matrix to be computed and factored and the structure currents to be computed if these operations have not already been performed. Hence, all required input parameters must be set before the RpCard() method is called.

At a single frequency, any number of RpCard() calls may occur in sequence so that different field-point spacings may be used over different regions of space. If automatic frequency stepping is being used (i.e., inNfrq on the FrCard() method is greater than one), only one RpCard() method will act as data inside the loop. Subsequent calls to RpCard() will calculate patterns at the final frequency.

When both nTheta and nPhi are greater than one, the angle theta (or Z) will be stepped faster than phi.

When a ground plane has been specified, field points should not be requested below the ground (theta greater than 90 degrees or Z less than zero.)

func (*NecppCtx) ScCard 

func (n *NecppCtx) ScCard(i2 int, x3 float64, y3 float64, z3 float64, x4 float64, y4 float64, z4 float64) error

ScCard makes a Surface Patch Continuation (SC) card.

Parameters: 

i2  Weird integer parameter.
x3 The x coordinate of patch corner 3.
y3 The y coordinate of patch corner 3.
z3 The z coordinate of patch corner 3.
x4 The x coordinate of patch corner 4.
y4 The y coordinate of patch corner 4.
z4 The z coordinate of patch corner 4.

All co-ordinates are in meters.

func (*NecppCtx) SpCard 

func (n *NecppCtx) SpCard(ns PatchType, x1 float64, y1 float64, z1 float64, x2 float64, y2 float64, z2 float64) error

SpCard makes a Surface Patch (SP) card.

Parameters: 

ns PatchType - the type of Patch, see those constants
	Arbitrary
	Rectangular
	Triangular
	Quadrilateral
x1 The x coordinate of patch corner1.
y1 The y coordinate of patch corner1.
z1 The z coordinate of patch corner1.
x2 The x coordinate of patch corner2.
y2 The y coordinate of patch corner2.
z2 The z coordinate of patch corner2.

All co-ordinates are in meters, except for arbitrary patches where the angles// are in degrees.

func (*NecppCtx) TlCard 

func (n *NecppCtx) TlCard(itmp1 int, itmp2 int, itmp3 int, itmp4 int, tmp1 float64, tmp2 float64, tmp3 float64, tmp4 float64, tmp5 float64, tmp6 float64) error

TlCard, presumably, makes an NEC2 TL Card.

func (*NecppCtx) Wire 

func (n *NecppCtx) Wire(tagId int, segmentCount int, xw1 float64, yw1 float64, zw1 float64, xw2 float64, yw2 float64, zw2 float64, rad float64, rdel float64, rrad float64) error

Wire creates a straight wire. The parameters are: 

tagId: the tag ID
segmentCount: the number of segments
xw1 The x coordinate of the wire starting point.
yw1 The y coordinate of the wire starting point.
zw1 The z coordinate of the wire starting point.
xw2 The x coordinate of the wire ending point.
yw2 The y coordinate of the wire ending point.
zw2 The z coordinate of the wire ending point.
rad The wire radius (meters)
rdel For tapered wires, the. Otherwise set to 1.0
rrad For tapered wires, the. Otherwise set to 1.0

All co-ordinates are in meters.

func (*NecppCtx) XqCard 

func (n *NecppCtx) XqCard(itmp1 ExecutionOption) error

XqCard causes program execution at points in the data stream where execution is not automatic. Options on the card also allow for automatic generation of radiation patterns in either of two vertical cuts.

Parameter: 

itmp1 - an ExecutionOption flag, per the ExecutionOption consts.

type PatchType 

type PatchType int

PatchType is the shape of a patch for the Surface Patch (SP Card). 

const (
	Arbitrary PatchType = iota // an arbitrary patch shape (the default)
	Rectangular
	Triangular
	Quadrilateral
)

type RpAveraging 

type RpAveraging int

RpAveraging is used to select the type of averaging for RP cards to set the calculation of average power gain over the region covered by field points.

RpAveraging flags:

• NoAvg - no averaging

• AvgGain - average gain computed.

• AvgGainPrtSuppressed - average gain computed, printing of gain at the field points used for averaging is suppressed. If nTheta or NPH is equal to one, average gain will not be computed for any value of A since the area of the region covered by field points vanishes. 

const (
	NoAvg RpAveraging = iota
	AvgGain
	AvgGainPrtSuppressed
)

type RpCalcMode 

type RpCalcMode int

RpCalcMode is used to select radiation patterns for RP cards.

RP card calculation flags:

• Normal - normal mode. Space-wave fields are computed. An infinite ground plane is included if it has been specified previously on a GN card; otherwise, the antenna is in free space.

• SurfaceWave - surface wave propagating along ground is added to the normal space wave. This option changes the meaning of some of the other parameters on the RP card as explained below, and the results appear in a special output format. Ground parameters must have been input on a GN card. The following options cause calculation of only the space wave but with special ground conditions. Ground conditions include a two-medium ground (cliff where the media join in a circle or a line), and a radial wire ground screen. Ground parameters and dimensions must be input on a GN or GD card before the RP card is read. The RP card only selects the option for inclusion in the field calculation. (Refer to the GN and GD cards for further explanation.)

• LinearCliff - linear cliff with antenna above upper level. Lower medium parameters are as specified for the second medium on the GN card or on the GD card.

• CircularCliff - circular cliff centered at origin of coordinate system: with antenna above upper level. Lower medium parameters are as specified for the second medium on the GN card or on the GD card.

• RadialScreen - radial wire ground screen centered at origin.

• RadialLinearCliff - both radial wire ground screen and linear cliff.

• RadialCircularCliff - both radial wire ground screen ant circular cliff. 

const (
	Normal RpCalcMode = iota
	SurfaceWave
	LinearCliff
	CircularCliff
	RadialScreen
	RadialLinearCliff
	RadialCircularCliff
)

type RpGain 

type RpGain int

RpGain is used to select the type of gain for RP cards for standard printing and normalization constants. These ones have self explanatory names. 

const (
	PowerGain RpGain = iota
	DirectiveGain
)

type RpNormalization 

type RpNormalization int

RpNormalization is used to select the normalization type for RP cards.

Radiation pattern normalization flags:

• NoNormalization - no normalized gain.

• MajorAxisNorm - major axis gain normalized.

• MinorAxisNorm - minor axis gain normalized.

• VerticalAxisNorm - vertical axis gain normalized.

• HorizontalAxisNorm - horizontal axis gain normalized.

• TotalNormalized - total gain normalized. 

const (
	NoNormalization RpNormalization = iota
	MajorAxisNorm
	MinorAxisNorm
	VerticalAxisNorm
	HorizontalAxisNorm
	TotalNormalized
)

type RpOutputFormat 

type RpOutputFormat int

RpOutputFormat is used to select the output format for RP cards.

• MajorMinor - major axis, minor axis and total gain printed.

• VerticalHorizontal - vertical, horizontal ant total gain printed. 

const (
	MajorMinor RpOutputFormat = iota
	VerticalHorizontal
)

type WireKernel 

type WireKernel int

WireKernel sets the type of wire kernel to use with EkCard

• ReturnToNormal - Return to normal kernel

• ExtendedThinWire - Use extended thin wire kernel 

const (
	ReturnToNormal WireKernel = iota - 1
	ExtendedThinWire
)

Source Files

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Path Synopsis
Golang example using libnecpp as a library.
 Golang example using libnecpp as a library.

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