Documentation

This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English verison of the page.

Note: This page has been translated by MathWorks. Please click here
To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

reflector

Create reflector-backed antenna

Description

The reflector object is a reflector-backed antenna on the X-Y-Z 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.

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

expand all

Antenna type used as an exciter, specified as an object. Except reflector and cavity antenna elements, you can use all the single elements in the Antenna Toolbox™ as an exciter.

Example: 'Exciter',dipole

Type of dielectric material used as a substrate, specified as a 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

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.

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 antenna, specified as a scalar or vector with each element unit in degrees.

Example: 'Tilt',90

Example: 'Tilt',[90 90 0]

Data Types: double

Tilt axis of the antenna, specified as:

  • A three-element vector of Cartesian coordinates in meters. In this case, each vector starts at the origin and lies along the specified points on the X, Y, and Z axes.

  • Two points in space as three-element vectors of Cartesian coordinates. In this case, the antenna rotates along the line joining the two points.

  • A string input for simple rotations around the principal planes, X, Y, or Z.

For more information see, Rotate Antenna and Arrays

Example: 'TiltAxis',[0 1 0]

Example: 'TiltAxis',[0 0 0;0 1 0]

Example: 'TiltAxis','Z'

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 for resonance at specified frequency
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
patternRadiation pattern 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

expand all

Create a reflector backed dipole that has 30cm length, 25cm width and spaced 7.5cm 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
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

show(rf)

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)

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

figure
pattern(rf,1e9)

Create a reflector backed dipole that has 30cm length, 25cm width and spaced 7.5cm 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
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

show(rf)

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

Design a dipole antenna at 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 1GHz.

figure
pattern(d,1e9);

Use FR4 as the dielectric substrate.

t = dielectric('FR4')
eps_r = t.EpsilonR;
lambda_0 = physconst('lightspeed')/1e9;
lambda_d = lambda_0/sqrt(eps_r);
t = 

  dielectric with properties:

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

For more materials see <a href="matlab:openDielectricCatalog">catalog</a>

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 excitor and FR4 as the substrate.

rf = design(reflector,1e9);
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 vlaues.

  • Gain of the dipole in free space = 2.11 dBi

  • Gain of the dipole on substrate = 1.93 dBi

References

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

Introduced in R2015a

Was this topic helpful?