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

Syntax

rf = reflector

rf = reflector(Name=Value)

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.

rf = reflector(Name=Value) creates a reflector antenna, with additional properties specified by 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 not specified retain their default values.

For example, r = reflector(Exciter=yagiUda) creates a reflector antenna with a Yagi Uda as an exciter.

Properties

Exciter — Antenna or array type used as exciter

dipole (default) | antenna object | array object | empty array

Exciter antenna or array type, specified as a single-element antenna object, an array object, or an empty array. Except for reflector and cavity antenna elements, you can use any Antenna Toolbox™ antenna or array element as an exciter. To create the cavity backing structure without the exciter, specify this property as an empty array.

Example: horn

Example: linearArray(Element=patchMicrostrip)

Example: []

Substrate — Type of dielectric material

"Air" (default) | dielectric object

Substrate dielectric material, specified as "air" or a dielectric object. For more information about dielectric substrate meshing, see Meshing.

Note

The substrate dimensions must be equal to the groundplane dimensions.

Example: dielectric("FR4")

GroundPlaneLength — Reflector length along x-axis

0.2000 (default) | scalar

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: 3

Data Types: double

GroundPlaneWidth — Reflector width along y-axis

0.2000 (default) | scalar

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: 2.5

Data Types: double

Spacing — Distance between reflector and exciter

0.0750 (default) | scalar

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

Example: 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: metal("Copper")

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: 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 0 (disable) or 1 (enable). By default, probe feed is disabled.

Example: 1

Data Types: double | logical

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'

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 Reflector-Backed Dipole Antenna

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,Exciter=d);
show(rf)

Radiation Pattern of Reflector Backed Antenna

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

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,Exciter=di);
show(rf)

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

figure
pattern(rf,1e9)

Create Reflector-Backed Antenna Over Infinite Ground Plane

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,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)

Antenna On Dielectric Substrate - Compare Gain Values

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);

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)

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

rf.GroundPlaneLength = 0;
show(rf)

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

figure
pattern(rf,1e9);

Compare the gain values.

• Gain of the dipole in free space = 2.11 dBi

• Gain of the dipole on substrate = 1.93 dBi

Create Reflector-Backed Rectangular Array of Bowtie Antennas

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)

Create Rectangular Array of Microstrip Patch with Reflector Backing Structure

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)

References

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

Version History

Introduced in R2015a