cavity

Create cavity-backed antenna

Description

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

Creation

Syntax

c = cavity

c = cavity(Name,Value)

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.

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

Exciter — Antenna or array type used as exciter

dipole (default) | antenna object | array object

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')

Substrate — Type of dielectric material

'Air' (default) | object

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 ground plane dimensions.

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

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

Length — Length of rectangular cavity along x-axis

0.2000 (default) | scalar

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

Example: 'Length',30e-2

Data Types: double

Width — Width of rectangular cavity along y-axis

0.2000 (default) | scalar

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

Example: 'Width',25e-2

Data Types: double

Height — Height of rectangular cavity along z-axis

0.0750 (default) | scalar

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

Example: 'Height',7.5e-2

Data Types: double

Spacing — Distance between exciter and base of cavity

0.0750 (default) | scalar

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

Example: 'Spacing',7.5e-2

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

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

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

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

EnableProbeFeed — Create probe feed from backing structure to exciter

0 (default) | 1

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 — 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: 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: TiltAxis = 'Z'

Note

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

Data Types: double

Object Functions

show	Display antenna, array structures or shapes
info	Display information about antenna or array
axialRatio	Axial ratio of antenna
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
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, 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
rcs	Calculate and plot radar cross section (RCS) of platform, antenna, or array
returnLoss	Return loss of antenna; scan return loss of array
sparameters	Calculate S-parameter for antenna and antenna array objects
vswr	Voltage standing wave ratio of antenna

Examples

Create and View Cavity-Backed Antenna

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)

Radiation Pattern of Cavity-Backed Antenna

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)

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

figure
pattern(c,1e9)

Create Rectangular Array with Cavity Backing Structure

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)

Create Fractal Carpet Antenna with Cavity Backing structure

Create and visualize a cavity-backed fractal carpet antenna

e = fractalCarpet('Substrate',dielectric('FR4'));
ant = cavity('Exciter',e)

ant = 
  cavity with properties:

            Exciter: [1x1 fractalCarpet]
          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)

References

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

Version History

Introduced in R2015a