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cassegrain

Create Cassegrain antenna

Description

The cassegrain object creates a Cassegrain antenna. A Cassegrain antenna is a parabolic antenna using a dual reflector system. In this antenna, the feed antenna is mounted at or behind the surface of the main parabolic reflector and aimed at the secondary reflector. For more information see, Architecture of Cassegrain Antenna.

Cassegrain antennas are used in applications such as satellite ground-based systems.

Creation

Description

example

ant = cassegrain creates a conical horn fed Cassegrain antenna with a resonating frequency of 18.51 GHz. This antenna gives maximum gain when operated at 18 GHz.

ant = cassegrain(Name,Value) sets properties using one or more name-value pairs. For example, ant = cassegrain('Radius',[0.4 0.22]) creates a Cassegrain antenna with the main reflector with radius 0.4 m and the secondary reflector with radius 0.22 m.

Properties

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Antenna type used as exciter, specified as an antenna or an array object.

Example: 'Exciter',dipole

Example: ant.Exciter = dipole

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

Radius of the main and subreflector, specified as a two-element vector with each element unit in meters. The first element specifies the radius of the main reflector, and the second element specifies the radius of the subreflector.

Example: 'Radius',[0.4 0.2]

Example: ant.Radius = [0.4 0.2]

Data Types: double

Focal length of the main and subreflector, specified as a two-element vector with each element unit in meters. The first element specifies the focal length of the main reflector and the second element specifies the focal length of the subreflector.

Example: 'FocalLength',[0.35 0.2]

Example: ant.FocalLength = [0.35 0.2]

Data Types: double

Lumped elements added to the antenna feed, specified as a lumped element object. You can add a load anywhere on the surface of the antenna. By default, the load is at the feed. For more information, see lumpedElement.

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

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

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

Solver for antenna analysis, specified as the comma-separated pair consisting of 'SolverType' and 'MoM-PO' or 'PO' (Physical Optics) or 'MoM' (Method of Moments) or 'FMM' (Fast Multipole Method).

Example: 'SolverType','MOM'

Data Types: char

Object Functions

showDisplay antenna or array structure; display shape as filled patch
solverAccess FMM solver for electromagnetic analysis
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
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 and view a Cassegrain antenna.

ant = cassegrain
ant = 
  cassegrain with properties:

        Exciter: [1x1 hornConical]
         Radius: [0.3175 0.0330]
    FocalLength: [0.2536 0.1416]
           Tilt: 0
       TiltAxis: [1 0 0]
           Load: [1x1 lumpedElement]
     SolverType: 'MoM-PO'

show(ant)

Figure contains an axes object. The axes object with title cassegrain antenna element contains 7 objects of type patch, surface. These objects represent PEC, feed.

Plot the radiation pattern of the antenna at 18.3 GHz.

mesh(ant,'maxEdgeLength',14e-3)

Figure contains an axes object and other objects of type uicontrol. The axes object with title Metal mesh contains 2 objects of type patch, surface.

figure;
pattern(ant,18.3e9)

Figure contains an axes object and other objects of type uicontrol. The axes object contains 7 objects of type patch, surface.

Create a rectangular array of crossed dipole antennas.

e = dipoleCrossed('Tilt',90,'TiltAxis',[0 1 0]);
arr = rectangularArray('Element',e,'Rowspacing',0.03,'ColumnSpacing',0.03);

Use the rectangular array arr to excite a Cassegrain antenna.

ant = cassegrain('Exciter',arr)
ant = 
  cassegrain with properties:

        Exciter: [1x1 rectangularArray]
         Radius: [0.3175 0.0330]
    FocalLength: [0.2536 0.1416]
           Tilt: 0
       TiltAxis: [1 0 0]
           Load: [1x1 lumpedElement]
     SolverType: 'MoM-PO'

show(ant)

Figure contains an axes object. The axes object with title cassegrain antenna element contains 21 objects of type patch, surface. These objects represent PEC, feed.

More About

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References

[1] Dandu, Obulesu. "Optimized Design of Axillary Symmetric Cassegrain Reflector Antenna Using Iterative Local Search Algorithm"

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

Introduced in R2019b