customAntennaStl

Create custom 3-D antenna geometry using STL, STEP, or IGES files

Since R2020a

Description

The customAntennaStl object creates a 3-D antenna geometry and mesh using stereolithography (STL), standard for the exchange of product model data (STEP), or initial graphics exchange specification (IGES) files. An STL file defines a 3-D surface in the form of points and triangles. While STEP and IGES files save the 3-D geometry data in ASCII format.

Creation

Syntax

ca = customAntennaStl

ca = customAntennaStl(Name=Value)

Description

ca = customAntennaStl returns a 3-D antenna represented by a custom geometry with default property values.

ca = customAntennaStl(Name=Value) sets properties using one or more name-value arguments. Name is the property name and Value is the corresponding value. You can specify several name-value arguments in any order as Name1=Value1,...,NameN=ValueN. Properties that you do not specify, retain their default values.

For example, ca = customAntennaStl(FileName="plate.stl",PhaseShift=10) creates a custom antenna from the geometry specified in the plate.stl file and applies a phase shift of 10 degrees to the element.

Properties

FileName — Name of geometry information file to import

"[]" (default) | string scalar

Name of the geometry information file to import, specified as a string scalar.

Example: "plate.stl"

Data Types: string

Units — Units for geometry

"m" (default) | "mm" | "cm" | "um" | "ft" | "in"

Units for the geometry imported from the STL, STEP, or IGES file, specified as "m", "mm", "cm", "um", "ft", or "in".

Note

This property is read-only for STEP and IGES files.

Example: "mm"

Data Types: string

FeedLocation — Antenna feed location

[] (default) | three-element real vector

This property is read-only.

Antenna feed location, specified as a three-element real vector in meters. The first, second, and third elements of the vector are the x-, y-, and z- coordinates, respectively, in a Cartesian coordinate system.

This property displays the antenna feed location that you set using the createFeed function.

Data Types: double

AmplitudeTaper — Excitation amplitude of antenna elements

1 (default) | positive scalar

Excitation amplitude of antenna elements, specified as a positive scalar in volts.

Example: 1.8

Data Types: double

PhaseShift — Phase shift for antenna elements

0 (default) | numeric scalar

Phase shift for the antenna elements, specified as a numeric scalar in degrees.

Example: 10

Data Types: double

UseFileAsMesh — Option to use input geometry file as mesh

false or 0 (default) | true or 1

Option to use the input geometry file directly as a mesh for analysis, specified as a numeric or logical 1 (true) or 0 (false). To use the input file as a mesh, set this property to 1 (true).

Example: 1

Data Types: logical

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

Tilt angle of the antenna in degrees, specified as a scalar or vector. For more information, see Rotate Antennas and Arrays.

Example: 90

Example: Tilt=[90 90],TiltAxis=[0 1 0;0 1 1] tilts the antenna at 90 degrees about the two axes defined by the vectors.

Data Types: double

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector | 2-by-3 matrix | "X" | "Y" | "Z"

Tilt axis of the antenna, specified as one of these values:

• Three-element vector of Cartesian coordinates in meters. In this case, each coordinate in the vector starts at the origin and lies along the specified points on the x-, y-, and z-axes.

• Two points in space, specified as a 2-by-3 matrix corresponding to two three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points.

• "x", "y", or "z" to describe a rotation about the x-, y-, or z-axis, respectively.

For more information, see Rotate Antennas and Arrays.

Example: [0 1 0]

Example: [0 0 0;0 1 0]

Example: "Z"

Data Types: double | string

Object Functions

axialRatio	Calculate and plot axial ratio of antenna or array
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
createFeed	Create feed location for customAntennaStl object
current	Current distribution on antenna or array surface
efficiency	Calculate and plot radiation efficiency of antenna or array
EHfields	Electric and magnetic fields of antennas or embedded electric and magnetic fields of antenna element in arrays
feedCurrent	Calculate current at feed for antenna or array
impedance	Calculate and plot input impedance of antenna or scan impedance of array
info	Display information about antenna, array, or platform
memoryEstimate	Estimate memory required to solve antenna or array mesh
mesh	Mesh properties of metal, dielectric antenna, or array structure
meshconfig	Change meshing mode of antenna, array, custom antenna, custom array, or custom geometry
msiwrite	Write antenna or array analysis data to MSI planet file
pattern	Plot radiation pattern and phase of antenna or array or embedded pattern of antenna element in array
patternAzimuth	Azimuth plane radiation pattern of antenna or array
patternElevation	Elevation plane radiation pattern of antenna or array
peakRadiation	Calculate and mark maximum radiation points of antenna or array on radiation pattern
rcs	Calculate and plot monostatic and bistatic radar cross section (RCS) of platform, antenna, or array
returnLoss	Calculate and plot return loss of antenna or scan return loss of array
show	Display antenna, array structures, shapes, or platform
sparameters	Calculate S-parameters for antenna or array
stlwrite	Write mesh information to STL file
vswr	Calculate and plot voltage standing wave ratio (VSWR) of antenna or array element

Examples

Create and Display Custom 3-D Antenna

Use geometry files with different extensions to create custom antennas. Create custom 3-D antennas using a customAntennaStl object.

c1 = customAntennaStl(FileName="plateMesh.stl");
c2 = customAntennaStl(FileName="cylinder.step");
c3 = customAntennaStl(FileName="cube.iges");

Create an antenna feed and calculate the antenna impedance at 110 MHz for the first and third antennas and 1 GHz for the second antenna.

c1.createFeed([0 0 0],1);
Z1 = impedance(c1,110e6);
disp(c1)

  customAntennaStl with properties:

          FileName: "plateMesh.stl"
             Units: 'm'
      FeedLocation: [0 0 0]
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

c2.createFeed([0 -0.1 -0.05],1);
Z2 = impedance(c2,1e9);
disp(c2)

  customAntennaStl with properties:

          FileName: "cylinder.step"
             Units: 'mm'
      FeedLocation: [0 -0.1000 -0.0500]
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

c3.createFeed([-0.05 -0.1 0.05],1);
Z3 = impedance(c3,110e6);
disp(c3)

  customAntennaStl with properties:

          FileName: "cube.iges"
             Units: 'mm'
      FeedLocation: [-0.0500 -0.1000 0.0500]
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

Display the structure of custom 3-D antennas.

figure
show(c1)

figure
show(c2)

figure
show(c3)

Create Antenna Feed in Custom Antenna STL File

Create a customAntennaStl object using the specified STL file.

ant = customAntennaStl

ant = 
  customAntennaStl with properties:

          FileName: []
             Units: 'm'
      FeedLocation: []
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

ant.FileName ="patchMicrostrip_ColumnFeed.stl"

ant = 
  customAntennaStl with properties:

          FileName: "patchMicrostrip_ColumnFeed.stl"
             Units: 'm'
      FeedLocation: []
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

Specify the FeedLocation and NumEdges inputs to the createFeed function. Select the edges based on the distance between the feed location and the midpoints of the edges. Edges can be single-feed or a closed polygon.

ant.createFeed([-0.018750000000000 0 0],8)
show(ant)

Plot the current distribution at 1.75 GHz.

figure
current(ant,1.75e9,Scale="log")

Calculate the impedance at 1.75 GHz.

z = impedance(ant,1.75e9)

z = 
83.3968 -52.1467i

Create Antenna Feed Using UI Figure Window

Create a customAntennaStl object.

ant = customAntennaStl;

Import the STL files.

ant.FileName = "patchMicrostrip_ColumnFeed.stl";

Create the antenna feed using the UI figure window.

createFeed(ant);

The UI figure window contains the Slice Antenna pane and the Add Feed pane.

Click Slicer Mode, then click YZ to select the plane along which to slice your antenna.

Select the region to hide and then click Hide to hide the selected region.

Repeat the process until you reach the region of interest.

Select Select a Feeding Edge or Polygon under the Add Feed pane to select the desired feeding edge or feeding polygon.

Select the edges of the column that forms a closed polygon. The selected edges must be connected to other edges, otherwise the UI figure window displays an error.

Click OK to define the selected edges as feeding edges. The software displays the structure with the feed.

The software also displays the feed location.

Verify the location of the antenna feed.

ant

ant = 
  customAntennaStl with properties:

          FileName: "patchMicrostrip_ColumnFeed.stl"
             Units: 'm'
      FeedLocation: []
    AmplitudeTaper: 1
        PhaseShift: 0
     UseFileAsMesh: 0
              Tilt: 0
          TiltAxis: [1 0 0]

References

[1] Balanis, Constantine A. Antenna Theory: Analysis and Design. Fourth edition. Hoboken, New Jersey: Wiley, 2016.

Version History

Introduced in R2020a

R2023b: Generate antenna geometry for STEP and IGES files

You can now generate 3-D antenna geometry and a mesh using STEP and IGES files.