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reflector

Create reflector-backed antenna

Description

The reflector object is a reflector-backed antenna on the xyz- plane. The default reflector antenna uses a dipole as an exciter. The feed point is on the exciter.

Creation

Description

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

example

rf = reflector(Name,Value) creates a reflector 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'); rf.Substrate = d

Reflector length along the x-axis, specified a scalar in meters. By default, ground plane length is measured along the x-axis. Setting 'GroundPlaneLength' toInf, uses the infinite ground plane technique for antenna analysis. You can also set the 'GroundPlaneLength' to zero.

Example: 'GroundPlaneLength',3

Data Types: double

Reflector width along the y-axis, specified as a scalar in meters. By default, ground plane width is measured along the y-axis. Setting 'GroundPlaneWidth' toInf, uses the infinite ground plane technique for antenna analysis. You can also set the 'GroundPlaneWidth' to zero.

Example: 'GroundPlaneWidth',2.5

Data Types: double

Distance between the reflector and the exciter, specified as a scalar in meters. By default, the exciter is placed along the x-axis.

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. For more information, see lumpedElement.

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

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

Create probe feed from backing structure to exciter, specified as 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 around 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
rcsCalculate and plot radar cross section (RCS) of platform, antenna, or array
returnLossReturn loss of antenna; scan return loss of array
sparametersCalculate S-parameter for antenna and antenna array objects
vswrVoltage standing wave ratio of antenna

Examples

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Create a reflector backed dipole that has 30 cm length, 25 cm width and spaced 7.5 cm from the dipole for operation at 1 GHz.

d = dipole('Length',0.15,'Width',0.015, 'Tilt',90,'TiltAxis',[0 1 0]);
rf = reflector('GroundPlaneLength',30e-2, 'GroundPlaneWidth',25e-2,...
              'Spacing',7.5e-2);
rf.Exciter = d
rf = 
  reflector with properties:

              Exciter: [1x1 dipole]
            Substrate: [1x1 dielectric]
    GroundPlaneLength: 0.3000
     GroundPlaneWidth: 0.2500
              Spacing: 0.0750
      EnableProbeFeed: 0
            Conductor: [1x1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

show(rf)

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

Create a reflector backed dipole antenna using a dielectric substrate 'FR4'.

d = dielectric('FR4');
di = dipole('Length',0.15,'Width',0.015, 'Tilt',90,'TiltAxis','Y');
rf = reflector('GroundPlaneLength',30e-2, 'GroundPlaneWidth',25e-2, ...
               'Spacing',7.5e-3,'Substrate',d);
rf.Exciter = di;
show(rf)

Figure contains an axes object. The axes object with title reflector 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(rf,1e9)

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

Create a reflector backed dipole that has infinite length, 25 cm width and spaced 7.5 cm from the dipole for operation at 1 GHz.

d = dipole('Length',0.15,'Width',0.015, 'Tilt',90,'TiltAxis',[0 1 0]);
rf = reflector('GroundPlaneLength',inf, 'GroundPlaneWidth',25e-2,...
              'Spacing',7.5e-2);
rf.Exciter = d
rf = 
  reflector with properties:

              Exciter: [1x1 dipole]
            Substrate: [1x1 dielectric]
    GroundPlaneLength: Inf
     GroundPlaneWidth: 0.2500
              Spacing: 0.0750
      EnableProbeFeed: 0
            Conductor: [1x1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

show(rf)

Figure contains an axes object. The axes object with title dipole over infinite ground plane contains 4 objects of type patch, surface. These objects represent PEC, feed, infinite ground.

Compare the gain values of a dipole antenna in free space and dipole antenna on a substrate.

Design a dipole antenna at a frequency of 1 GHz.

d = design(dipole,1e9);
l_by_w = d.Length/d.Width;
d.Tilt = 90;
d.TiltAxis = [0 1 0];

Plot the radiation pattern of the dipole in free space at 1 GHz.

figure
pattern(d,1e9);

Figure contains an axes object and other objects of type uicontrol. The axes object contains 3 objects of type patch, surface.

Use FR4 as the dielectric substrate.

t = dielectric('FR4')
t = 
  dielectric with properties:

           Name: 'FR4'
       EpsilonR: 4.8000
    LossTangent: 0.0260
      Thickness: 0.0060

For more materials see catalog

eps_r = t.EpsilonR;
lambda_0 = physconst('lightspeed')/1e9;
lambda_d = lambda_0/sqrt(eps_r);

Adjust the length of the dipole based on the wavelength.

d.Length = lambda_d/2;
d.Width = d.Length/l_by_w;

Design a reflector at 1 GHz with the dipole as the exciter and FR4 as the substrate.

rf = reflector('Exciter',d,'Spacing',7.5e-3,'Substrate',t);
rf.GroundPlaneLength = lambda_d;
rf.GroundPlaneWidth = lambda_d/4;
figure
show(rf)

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

Remove the groundplane for plotting the gain of the dipole on the substrate.

rf.GroundPlaneLength = 0;
show(rf)

Figure contains an axes object. The axes object with title reflector antenna element contains 4 objects of type patch, surface. These objects represent PEC, feed, FR4.

Plot the radiation pattern of the dipole on the substrate at 1 GHz.

figure
pattern(rf,1e9);

Figure contains an axes object and other objects of type uicontrol. The axes object contains 4 objects of type patch, surface. This object represents FR4.

Compare the gain values.

  • Gain of the dipole in free space = 2.11 dBi

  • Gain of the dipole on substrate = 1.93 dBi

Create a rectangular array of the bowtie antennas.

b = bowtieTriangular('Length',0.05)
b = 
  bowtieTriangular with properties:

        Length: 0.0500
    FlareAngle: 90
     Conductor: [1x1 metal]
          Tilt: 0
      TiltAxis: [1 0 0]
          Load: [1x1 lumpedElement]

rectArr = rectangularArray('Element',b,'RowSpacing',0.18,'ColumnSpacing',0.18)
rectArr = 
  rectangularArray with properties:

           Element: [1x1 bowtieTriangular]
              Size: [2 2]
        RowSpacing: 0.1800
     ColumnSpacing: 0.1800
           Lattice: 'Rectangular'
    AmplitudeTaper: 1
        PhaseShift: 0
              Tilt: 0
          TiltAxis: [1 0 0]

Create a rectangular array with reflector backing structure.

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

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

show(ant)

Figure contains an axes object. The axes object with title reflector antenna element contains 11 objects of type patch, surface. These objects represent PEC, feed.

Create a reflector-backed rectangular array of microstrip patch antennas.

p = patchMicrostrip('Substrate',dielectric('FR4'));
ra = rectangularArray('Element',p,'RowSpacing',0.075,'ColumnSpacing',0.1);
ant = reflector('Exciter',ra,'GroundPlaneLength',0.4,'GroundPlaneWidth',0.3)
ant = 
  reflector with properties:

              Exciter: [1x1 rectangularArray]
            Substrate: [1x1 dielectric]
    GroundPlaneLength: 0.4000
     GroundPlaneWidth: 0.3000
              Spacing: 0.0750
      EnableProbeFeed: 0
            Conductor: [1x1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

show(ant)

Figure contains an axes object. The axes object with title reflector antenna element contains 17 objects of type patch, surface. These objects represent PEC, feed, FR4.

References

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

Introduced in R2015a