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cavity

Create cavity-backed antenna

Description

The cavity object is a cavity-backed antenna located on the X-Y-Z plane. The default cavity antenna has a dipole as an exciter. The feed point is on the exciter.

Creation

Description

c = cavity creates a cavity backed antenna located on the X-Y-Z plane. By default, the dimensions are chosen for an operating frequency of 1 GHz.

example

c = cavity(Name,Value) creates a cavity-backed 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 not specified retain their default values.

Properties

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Antenna type used as an exciter, specified as any single-element antenna object. Except reflector and cavity antenna elements, you can use any of the antenna elements or array elements in the Antenna Toolbox™ as an exciter.

Example: 'Exciter',horn

Example: ant.Exciter = horn

Example: ant.Exciter = linearArray('patchMicrostrip')

Type of dielectric material used as a substrate, specified as an object. For more information see, dielectric. For more information on dielectric substrate meshing, see Meshing.

Note

The substrate dimensions must be equal to the groundplane dimensions.

Example: d = dielectric('FR4'); 'Substrate',d

Example: d = dielectric('FR4'); cavity.Substrate = d

Length of the rectangular cavity along the x-axis, specified as a scalar in meters.

Example: 'Length',30e-2

Data Types: double

Width of the rectangular cavity along the y-axis, specified as a scalar in meters.

Example: 'Width',25e-2

Data Types: double

Height of the rectangular cavity along the z-axis, specified as a scalar in meters.

Example: 'Height',7.5e-2

Data Types: double

Distance between the exciter and the base of the cavity, specified as a scalar in meters.

Example: 'Spacing',7.5e-2

Data Types: double

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

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: c.Load = lumpedElement('Impedance',75)

Create probe feed from backing structure to exciter, specified as a 0 or 1. By default, probe feed is not enabled.

Example: 'EnableProbeFeed',1

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: 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

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

showDisplay antenna or array structure; display shape as filled patch
infoDisplay information about antenna or array
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
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 or 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
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 cavity-backed dipole antenna with 30 cm length, 25 cm width, 7.5 cm height and spaced 7.5 cm from the bowtie for operation at 1 GHz.

c = cavity('Length',30e-2, 'Width',25e-2,'Height',7.5e-2,'Spacing',7.5e-2);
show(c)

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

Create a cavity-backed antenna using a dielectric substrate 'FR4'.

d = dielectric('FR4');
c = cavity('Length',30e-2,'Width',25e-2,'Height',20.5e-3,'Spacing',7.5e-3,...
    'Substrate',d)
c = 
  cavity with properties:

            Exciter: [1x1 dipole]
          Substrate: [1x1 dielectric]
             Length: 0.3000
              Width: 0.2500
             Height: 0.0205
            Spacing: 0.0075
    EnableProbeFeed: 0
          Conductor: [1x1 metal]
               Tilt: 0
           TiltAxis: [1 0 0]
               Load: [1x1 lumpedElement]

show(c)

Figure contains an axes. The axes with title cavity antenna element contains 6 objects of type patch, surface. These objects represent PEC, feed, FR4.

Plot the radiation pattern of the antenna at a frequency of 1 GHz.

figure
pattern(c,1e9)

Figure contains an axes and other objects of type uicontrol. The axes contains 6 objects of type patch, surface. This object represents FR4.

Create a rectangular array of E-shaped patch antenna.

rectArr = rectangularArray('Element',patchMicrostripEnotch,'RowSpacing',0.03,'ColumnSpacing',0.03);

Create a cavity-backed antenna with rectangular array exciter.

ant = cavity('Exciter',rectArr)
ant = 
  cavity with properties:

            Exciter: [1x1 rectangularArray]
          Substrate: [1x1 dielectric]
             Length: 0.2000
              Width: 0.2000
             Height: 0.0750
            Spacing: 0.0750
    EnableProbeFeed: 0
          Conductor: [1x1 metal]
               Tilt: 0
           TiltAxis: [1 0 0]
               Load: [1x1 lumpedElement]

show(ant)

Figure contains an axes. The axes with title cavity antenna element contains 16 objects of type patch, surface. These objects represent PEC, feed.

References

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

Introduced in R2015a