dipoleJ

Create J-dipole antenna

Description

Use the dipoleJ object to create a J-dipole on the Y-Z plane. The antenna contains a half-wavelength radiator and a quarter-wavelength stub. By default, the antenna dimensions are for an operating frequency of 144 MHz.

Creation

Description

example

jdipole = dipoleJ creates a J-dipole antenna for an operating frequency of 144 MHz.

example

jdipole = dipoleJ(Name,Value) creates a J-dipole antenna with additional properties specified by one or more name-value pair arguments. For example, jdipole = dipoleJ('Width',0.2) creates a J-dipole with a strip width of 0.2 m. Enclose each property name in quotes.

Properties

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Radiator length, specified as a scalar in meters.

Example: 'RadiatorLength',0.9

Example: jdipole.RadiatorLength = 0.9

Data Types: double

Parallel line stub length, specified as a scalar in meters.

Example: 'StubLength',0.3

Example: jdipole.StubLength = 0.3

Data Types: double

Strip width, specified as a scalar in meters.

Example: 'StripWidth',0.0500

Example: jdipole.StripWidth = 0.0500

Data Types: double

Space between the parallel line stub and the radiator, specified as a scalar in meters.

Example: 'Spacing',0.0500

Example: jdipole.Spacing = 0.0500

Data Types: double

Signed distance to the feed from the base of stub on the large arm, specified as a scalar in meters.

Example: 'FeedOffset',0.0345

Example: jdipole.FeedOffset = 0.0345

Data Types: double

Lumped elements added to the antenna feed, specified as a lumped element object handle. You can add a load anywhere on the surface of the antenna. By default, the load is at the origin. For more information, see lumpedElement.

Example: 'Load',lumpedelement, where, lumpedelement is the object handle for the load created using lumpedElement.

Example: jdipole.Load = lumpedElement('Impedance',75)

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 degree about two axes, defined by vectors.

Data Types: double

Tilt axis of the antenna, specified as:

  • Three-element vectors of Cartesian coordinates in meters. In this case, each 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: ant.TiltAxis = 'Z'

Object Functions

showDisplay antenna or array structure; Display shape as filled patch
axialRatioAxial ratio of antenna
beamwidthBeamwidth of antenna
chargeCharge distribution on metal or dielectric antenna or array surface
currentCurrent distribution on metal or dielectric antenna or array surface
designDesign prototype antenna or arrays for resonance at specified frequency
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 or dielectric antenna or array structure
meshconfigChange mesh mode of antenna structure
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
returnLossReturn loss of antenna; scan return loss of array
sparametersS-parameter object
vswrVoltage standing wave ratio of antenna

Examples

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Create and view a default J-dipole antenna.

d = dipoleJ
d = 
  dipoleJ with properties:

    RadiatorLength: 0.9970
        StubLength: 0.4997
           Spacing: 0.0460
             Width: 0.0200
        FeedOffset: -0.6994
              Tilt: 0
          TiltAxis: [1 0 0]
              Load: [1x1 lumpedElement]

show(d)

Create and view a J-dipole antenna with the following specifications:

Radiator length = 0.978 m

Stub length = 0.485 m

FeedOffset = 0.049 m

dj = dipoleJ('RadiatorLength',0.978,'StubLength',0.485, ...
      'FeedOffset',0.070);
show(dj)

Calculate the impedance of the antenna over a frequency span 140MHz - 150MHz.

impedance(dj,linspace(140e6,150e6,51));

Introduced in R2018a