dipole

Create strip dipole antenna

Description

The dipole object is a strip dipole antenna on the Y-Z plane.

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 Y-Z plane.

Creation

Syntax

d = dipole

d = dipole(Name,Value)

Description

d = dipole creates a half-wavelength strip dipole antenna on the Y-Z plane.

d = dipole(Name,Value) creates a dipole antenna, with additional properties specified by one or more name-value pair arguments. Name is the property name and Value is the corresponding value. You can specify several name-value pair arguments in any order as Name1, Value1, ..., NameN, ValueN. Properties you do not specify retains their default values.

Properties

Length — Dipole length

2 (default) | scalar

Dipole length, specified as a scalar in meters. By default, the length is chosen for an operating frequency of 75 MHz.

Example: 'Length',3

Data Types: double

Width — Dipole width

0.1000 (default) | scalar

Dipole width, specified as a scalar in meters.

Note

Dipole width should be less than 'Length'/5 and greater than 'Length'/1001. [2]

Example: 'Width',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 Y-Z plane.

Example: 'FeedOffset',3

Data Types: double

Conductor — Type of metal material

'PEC' (default) | metal object

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: m = metal('Copper'); 'Conductor',m

Example: m = metal('Copper'); ant.Conductor = m

Load — Lumped elements

[1x1 lumpedElement] (default) | lumped element object handle

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

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

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

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

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: ant.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

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector of Cartesian coordinates | two three-element vectors of Cartesian coordinates | 'X' | 'Y' | 'Z'

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: ant.TiltAxis = 'Z'

Note

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

Data Types: double

Object Functions

show	Display antenna or array structure; display shape as filled patch
info	Display information about antenna or array
axialRatio	Axial ratio of antenna
beamwidth	Beamwidth of antenna
charge	Charge distribution on metal or dielectric antenna or array surface
current	Current distribution on metal or dielectric antenna or array surface
design	Design prototype antenna or arrays for resonance at specified frequency
efficiency	Radiation efficiency of antenna
EHfields	Electric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedance	Input impedance of antenna; scan impedance of array
mesh	Mesh properties of metal or dielectric antenna or array structure
meshconfig	Change mesh mode of antenna structure
optimize	Optimize antenna or array using SADEA optimizer
pattern	Radiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuth	Azimuth pattern of antenna or array
patternElevation	Elevation pattern of antenna or array
returnLoss	Return loss of antenna; scan return loss of array
sparameters	S-parameter object
vswr	Voltage standing wave ratio of 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)

References

[1] Balanis, C.A. Antenna Theory: Analysis and Design. 3rd Ed. New York: Wiley, 2005.

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