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dipoleHelix

Create helical dipole antenna

Description

The dipoleHelix object is a helical dipole antenna. The antenna is typically center-fed. You can move the feed along the antenna length using the feed offset property. Helical dipoles are used in satellite communications and wireless power transfers.

The width of the strip is related to the diameter of an equivalent cylinder by this equation

w=2d=4r

where:

  • w is the width of the strip.

  • d is the diameter of an equivalent cylinder.

  • r is the radius of an equivalent cylinder.

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. The default helical dipole antenna is center-fed. Commonly, helical dipole antennas are used in axial mode. In this mode, the helical dipole circumference is comparable to the operating wavelength, and has maximum directivity along its axis. In normal mode, the helical dipole radius is small compared to the operating wavelength. In this mode, the helical dipole radiates broadside, that is, in the plane perpendicular to its axis. The basic equation for the helical dipole antenna is:

x=rcos(θ)y=rsin(θ)z=Sθ

where:

  • r is the radius of the helical dipole.

  • θ is the winding angle.

  • S is the spacing between turns.

For a given pitch angle in degrees, use the helixpitch2spacing utility function to calculate the spacing between the turns in meters.

Creation

Description

example

dh = dipoleHelix creates a helical dipole antenna. The default antenna operates at around 2 GHz.

example

dh = dipoleHelix(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.

Properties

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Turn radius, specified as a scalar in meters.

Example: Radius=2

Data Types: double

Strip width, specified as a scalar in meters.

Note

Strip width should be less than 'Radius'/5 and greater than 'Radius'/250. [4]

Example: Width=5

Data Types: double

Number of turns of the helical dipole, specified a scalar.

Example: Turns=2

Data Types: double

Spacing between turns, specified as a scalar in meters.

Example: Spacing=1.5

Data Types: double

Direction of helical dipole turns (windings), specified as 'CW' or 'CCW'.

Example: WindingDirection='CW'

Data Types: char | string

Type of dielectric material used as the substrate, specified as a dielectric object. You can specify only one dielectric layer in the dipoleHelix object. Specify the same radius for all the turns. When you use a dielectric material other than air, the number of turns in the dipole helix must be greater than 1. For more information on dielectric substrate meshing, see Meshing.

Example: Substrate=dielectric('Teflon')

Type of the metal used as a conductor, specified as a metal material object. You can choose any metal from the MetalCatalog or specify a metal of your choice. For more information, see metal. For more information on metal conductor meshing, see Meshing.

Example: Conductor=metal('Copper');

Lumped elements added to the antenna feed, specified as a lumped element object. For more information, see lumpedElement.

Example: Load=lumpedElement(Impedance=75)

Signed distance from center along length and width of ground plane, specified as a two-element vector in meters. Use this property to adjust the location of the feedpoint relative to the ground plane and patch.

Example: FeedOffset=[0.01 0.01]

Data Types: double

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

Example: Tilt=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.

Note

The wireStack antenna object only accepts the dot method to change its properties.

Data Types: double

Tilt axis of the antenna, specified as:

  • 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, each specified as three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points in space.

  • A string input describing simple rotations around one of the principal axes, 'X', 'Y', or 'Z'.

For more information, see Rotate Antennas and Arrays.

Example: TiltAxis=[0 1 0]

Example: TiltAxis=[0 0 0;0 1 0]

Example: TiltAxis = 'Z'

Note

The wireStack antenna object only accepts the dot method to change its properties.

Data Types: double

Object Functions

showDisplay antenna, array structures or shapes
infoDisplay information about antenna or array
axialRatioAxial ratio of antenna
beamwidthBeamwidth of antenna
chargeCharge distribution on antenna or array surface
currentCurrent distribution on antenna or array surface
designDesign prototype antenna or arrays for resonance around specified frequency
efficiencyRadiation efficiency of antenna
EHfieldsElectric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedanceInput impedance of antenna; scan impedance of array
meshMesh properties of metal, dielectric antenna, or array structure
meshconfigChange mesh mode of antenna structure
optimizeOptimize antenna or array using SADEA optimizer
patternRadiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuthAzimuth pattern of antenna or array
patternElevationElevation pattern of antenna or array
rcsCalculate and plot radar cross section (RCS) of platform, antenna, or array
returnLossReturn loss of antenna; scan return loss of array
sparametersCalculate S-parameter for antenna and antenna array objects
vswrVoltage standing wave ratio of antenna

Examples

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Create a default helical dipole antenna and view it.

dh = dipoleHelix
dh = 
  dipoleHelix with properties:

              Radius: 0.0220
               Width: 1.0000e-03
               Turns: 3
             Spacing: 0.0350
    WindingDirection: 'CCW'
          FeedOffset: 0
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]
                Tilt: 0
            TiltAxis: [1 0 0]
                Load: [1x1 lumpedElement]

show(dh)

Figure contains an axes object. The axes object with title dipoleHelix antenna element contains 3 objects of type patch, surface. These objects represent PEC, feed.

Create a four-turn helical dipole antenna with a turn radius of 28 mm and a strip width of 1.2 mm.

dh = dipoleHelix(Radius=28e-3, Width=1.2e-3, Turns=4);
show(dh)

Figure contains an axes object. The axes object with title dipoleHelix antenna element contains 3 objects of type patch, surface. These objects represent PEC, feed.

Plot the radiation pattern of the helical dipole at 1.8 GHz.

pattern(dh, 1.8e9);

{"String":"Figure contains an axes object and other objects of type uicontrol. The axes object contains 3 objects of type patch, surface.","Tex":[],"LaTex":[]}

Create a custom dipole helix antenna with a Teflon dielectric substrate.

d = dielectric('Teflon');
dh = dipoleHelix(Radius=22e-3,Width=1e-3,Turns=3,Spacing=35e-3,FeedOffset=0,Substrate=d)
dh = 
  dipoleHelix with properties:

              Radius: 0.0220
               Width: 1.0000e-03
               Turns: 3
             Spacing: 0.0350
    WindingDirection: 'CCW'
          FeedOffset: 0
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]
                Tilt: 0
            TiltAxis: [1 0 0]
                Load: [1x1 lumpedElement]

View the dipole helix antenna.

show(dh)

Figure contains an axes object. The axes object with title dipoleHelix antenna element contains 5 objects of type patch, surface. These objects represent PEC, feed, Teflon.

References

[1] Balanis, C. A. Antenna Theory. Analysis and Design. 3rd Ed. Hoboken, NJ: John Wiley & Sons, 2005.

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

Version History

Introduced in R2016b