dipole

Create regular or AI-based strip dipole antenna

Description

The default dipole object creates a strip dipole antenna on the yz-plane, resonating around 70 MHz.

The width of the dipole is related to the diameter of an equivalent cylindrical dipole by the equation

$$w=2d=4r$$

where:

• d is the diameter of equivalent cylindrical dipole.

• r is the radius of equivalent cylindrical dipole.

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. The default strip dipole is center-fed. The feed point coincides with the origin. The origin is located on the yz-plane.

You can perform full-wave EM solver based analysis on the regular dipole antenna or you can create a dipole type AIAntenna and explore the design space to tune the antenna for your application using AI-based analysis.

Creation

Syntax

d = dipole

d = dipole(Name=Value)

Description

d = dipole creates a regular half-wavelength strip dipole antenna on the yz-plane with default property values. The default dimensions are chosen for an operating frequency of around 70 MHz.

d = dipole(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, d = dipole(Length=4) creates a strip dipole antenna with a length of 4 m. and default values for other properties.

• You can also create a regular dipole antenna resonating at a desired frequency using the design function. For example, to create a regular dipole antenna resonating at 100 MHz, use the following syntax:

  >> design(dipoleHelix,100e6)
  

  To analyze this antenna use object functions of the dipole. Use this workflow to design, tune, and analyze a dipole antenna using conventional full-wave solvers.

• You can create an AI-based dipole antenna resonating at a desired frequency using the design function. Using AI-based antenna models over conventional full-wave solvers significantly reduces the simulation time required to fine-tune the antenna to meet your design goals. Set the ForAI argument in the design function to true to create a dipole type AIAntenna object. To use this feature, you need license to the Statistics and Machine Learning Toolbox™ in addition to the Antenna Toolbox™. For example, to create an AI-based dipole antenna resonating at 100 MHz, use the following syntax:

  >> design(dipoleHelix,100e6,ForAI=true)
  

  The AI-based dipole antenna retains the Length and Width properties of the regular dipole antenna as tunable properties. Rest of the properties of the regular dipole antenna are converted into read-only properties in its AI-based version. To find the upper and lower bounds of the tunable properties, use the tunableRanges function.

  To analyze this antenna use object functions of the AIAntenna. Use this workflow to design, tune, and analyze a dipole antenna using its AI-based model. To create a regular dipole antenna from this AI-based antenna, use the exportAntenna function.

Properties

Length — Dipole length

2 (default) | positive scalar

Dipole length, specified as a positive scalar in meters. You can set this property for both regular and AI-based dipole antenna. For a regular dipole antenna, Length value does not have any upper and lower bounds.

For AI-based dipole antenna, Length value has upper and lower bounds. Use the tunableRanges function to get the upper and lower bound values.

Example: 3

Data Types: double

Width — Dipole width

0.1 (default) | positive scalar

Dipole width, specified as a positive scalar in meters. Dipole width must be less than Length/5 and greater than Length/1001. [2] You can set this property for both regular and AI-based dipole antenna. For a regular dipole antenna, Width value does not have any upper and lower bounds.

For AI-based dipole antenna, Width value has upper and lower bounds. Use the tunableRanges function to get the upper and lower bound values.

Example: 0.05

Data Types: double

FeedOffset — Signed distance from center of dipole

0 (default) | scalar

Signed distance from center of dipole, specified as a scalar in meters. The feed location is on yz-plane. You can set this property only for a regular dipole antenna. This property is read-only for the AI-based dipole antenna.

Example: 3

Data Types: double

Conductor — Type of metal material

metal("PEC") (default) | metal object

Type of the metal used as a conductor, specified as a metal object. You can choose any metal from the MetalCatalog or specify a metal of your choice. You can set this property only for a regular dipole antenna. For more information on metal conductor meshing, see Meshing.

Example: metal("Copper")

Load — Lumped elements

[1x1lumpedElement] (default) | lumpedElement object

Lumped elements added to the antenna feed, specified as a lumpedElement object. You can add a load anywhere on the surface of the antenna. By default, the load is at the feed. You can set this property only for a regular dipole antenna.

Example: Load=lumpedElement(Impedance=75)

Example: antenna.Load = lumpedElement(Impedance=75)

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
bandwidth	Calculate and plot absolute bandwidth of antenna or array
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
current	Current distribution on antenna or array surface
design	Design prototype antenna or arrays for resonance around specified frequency or create AI-based antenna from antenna catalog objects
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
optimize	Optimize antenna or array using SADEA optimizer
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
resonantFrequency	Calculate and plot resonant frequency of antenna
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
wireStack	Create single or multi-feed wire antenna

Examples

Create and View Dipole Antenna

Create and view a dipole with 2 m length and 0.5 m width.

d = dipole(Width=0.05)

d = 
  dipole with properties:

        Length: 2
         Width: 0.0500
    FeedOffset: 0
     Conductor: [1x1 metal]
          Tilt: 0
      TiltAxis: [1 0 0]
          Load: [1x1 lumpedElement]

show(d)

Impedance of Dipole Antenna

Calculate the impedance of a dipole over a frequency range of 50 MHz - 100 MHz.

d = dipole(Width=0.05);
impedance(d,linspace(50e6,100e6,51))

Infinite Reflector Backed Dielectric Substrate Antenna

Design a dipole antenna backed by a dielectric substrate and an infinite reflector.

Create a dipole antenna of length, 0.15 m, and width, 0.015 m.

d = dipole(Length=0.15,Width=0.015,Tilt=90,TiltAxis=[0 1 0]);

Create a reflector using the dipole antenna as an exciter and the dielectric, teflon as the substrate.

t = dielectric("Teflon")

t = 
  dielectric with properties:

           Name: 'Teflon'
       EpsilonR: 2.1000
    LossTangent: 2.0000e-04
      Thickness: 0.0060

For more materials see catalog

rf = reflector(Exciter=d,Spacing=7.5e-3,Substrate=t);

Set the groundplane length of the reflector to inf. View the structure.

rf.GroundPlaneLength = inf;
show(rf)

Calculate the radiation pattern of the antenna at 70 MHz.

pattern(rf,70e6)

Create AI Model Based Dipole Antenna

This example shows how to create an AI model based dipole antenna at 75 MHz and calculate its resonant frequency.

dAI = design(dipole,75e6,ForAI=true)

dAI = 
  AIAntenna with properties:

   Antenna Info
               AntennaType: 'dipole'
    InitialDesignFrequency: 75000000

   Tunable Parameters
                    Length: 1.8787
                     Width: 0.0400

Use 'showReadOnlyProperties(dAI)' to show read-only properties

Vary its length and width and calculate its resonant frequency.

dAI.Length = 1.86;
dAI.Width = 0.045;
resonantFrequency(dAI)

ans = 
7.5989e+07

Convert the AIAntenna to a regular dipole antenna.

d = exportAntenna(dAI)

d = 
  dipole with properties:

        Length: 1.8600
         Width: 0.0450
    FeedOffset: 0
     Conductor: [1x1 metal]
          Tilt: 0
      TiltAxis: [1 0 0]
          Load: [1x1 lumpedElement]

References

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

[2] Volakis, John. Antenna Engineering Handbook, 4th Ed. New York: Mcgraw-Hill, 2007.

Version History

Introduced in R2015a

R2023b: AI model based antenna analysis

Design, tune, and analyze this antenna using an AI model. Using AI-based antenna models over conventional full-wave solvers significantly reduces the simulation time required to fine-tune the antenna to meet your design goals. Set the ForAI argument in the design function to true to create a dipole type AIAntenna. To use this feature, you need license to the Statistics and Machine Learning Toolbox in addition to the Antenna Toolbox.