dipoleJ

Create J-dipole antenna

Description

The default dipoleJ object creates a J-dipole antenna on the yz-plane resonating around 141 MHz. The antenna contains a half-wavelength radiator and a quarter-wavelength stub.

Creation

Syntax

dj = dipoleJ

dj = dipoleJ(Name=Value)

Description

dj = dipoleJ creates a J-dipole antenna with default property values. The default dimensions are chosen for an operating frequency of around 141 MHz.

dj = dipoleJ(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, dj = dipoleJ(RadiatorLength=2) creates a J-dipole antenna with radiator length of 2 m. and default values for other properties.

Properties

RadiatorLength — Radiator length

0.9970 (default) | positive scalar

Radiator length, specified as a positive scalar in meters.

Example: 0.9

Data Types: double

StubLength — Parallel line stub length

0.4997 (default) | positive scalar

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

Example: 0.3

Data Types: double

Width — Strip width

0.0200 (default) | positive scalar

Strip width, specified as a positive scalar in meters.

Example: 0.0500

Data Types: double

Spacing — Space between the stub and radiator

0.0460 (default) | positive scalar

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

Example: 0.0500

Data Types: double

FeedOffset — Signed distance to feed from base of stub on large arm

0.0490 (default) | scalar

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

Example: 0.0345

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. For more information on metal conductor meshing, see Meshing.

Example: metal("Copper")

Load — Lumped elements

[1x1 lumpedElement] (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.

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

Default J-Dipole Antenna

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
         Conductor: [1x1 metal]
              Tilt: 0
          TiltAxis: [1 0 0]
              Load: [1x1 lumpedElement]

show(d)

Impedance of J-Dipole Antenna

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

1. Radiator length = 0.978 m

2. Stub length = 0.485 m

3. 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));

Version History

Introduced in R2018a