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monopoleTopHat

Create capacitively loaded monopole antenna over rectangular ground plane

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Description

The default monopoleTopHat object is a top-hat monopole antenna mounted over a rectangular ground plane resonating around 85.2 MHz. The monopole always connects with the center of top hat. The top hat builds up additional capacitance to ground within the structure. This capacitance reduces the resonant frequency of the antenna without increasing the size of the element.

The width of the monopole is related to the diameter of an equivalent cylindrical monopole by the expression

w=2d=4r

where:

  • d is the diameter of equivalent cylindrical monopole

  • r is the radius of equivalent cylindrical monopole.

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. The default top-hat monopole is center-fed. The feed point coincides with the origin. The origin is located on the xy- plane.

Creation

Syntax

mth = monopoleTopHat
mth = monopoleTopHat(Name,Value)

Description

mth = monopoleTopHat creates a capacitively loaded monopole antenna over a rectangular ground plane with default property values. The default dimensions are chosen for an operating frequency of around 85.2 MHz.

example

mth = monopoleTopHat(Name,Value) creates a capacitively loaded monopole 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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Monopole height, specified as a scalar in meters.

Example: 'Height',3

Data Types: double

Monopole width, specified as a scalar in meters.

Note

Monopole width should be less than 'Height'/4 and greater than 'Height'/1001. [2]

Example: 'Width',0.05

Data Types: double

Ground plane length along x-axis, specified as a scalar in meters. Setting 'GroundPlaneLength' to Inf, uses the infinite ground plane technique for antenna analysis.

Example: 'GroundPlaneLength',4

Data Types: double

Ground plane width along y-axis, specified as a scalar in meters. Setting 'GroundPlaneWidth' to Inf, uses the infinite ground plane technique for antenna analysis.

Example: 'GroundPlaneWidth',2.5

Data Types: double

Top hat length along x-axis, specified as a scalar in meters.

Example: 'TopHatLength',4

Data Types: double

Top hat width along y-axis, specified as a scalar in meters.

Example: 'TopHatWidth',4

Data Types: double

Signed distance from center along length and width of ground plane, specified as a two-element vector.

Example: 'FeedOffset',[2 1]

Data Types: double

Type of dielectric material used as the substrate, specified as a dielectric object. You can also specify multiple dielectric layers. When creating multiple dielectric layers, in the dielectric function, specify the name, thickness, loss tangent, and relative permittivity of each layer. For more information, see dielectric. For more information on dielectric substrate meshing, see Meshing.

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

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

Example: d = dielectric('Name',{'FR4','Teflon'},'Thickness',[0.5 0.5],'LossTangent',[0.002 0.002],'EpsilonR',[4.8 2.1]); mth = monopoleTopHat('Substrate',d)

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: mth.Load = lumpedElement('Impedance',75)

Tilt angle of the antenna in degrees, specified as a scalar or vector. For more information, see Rotate Antennas and Arrays.

Example: 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.

Data Types: double

Tilt axis of the antenna, specified as one of these values:

  • 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, specified as a 2-by-3 matrix corresponding to two three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points.

  • "x", "y", or "z" to describe a rotation about the x-, y-, or z-axis, respectively.

For more information, see Rotate Antennas and Arrays.

Example: [0 1 0]

Example: [0 0 0;0 1 0]

Example: "Z"

Data Types: double | string

Object Functions

axialRatioCalculate and plot axial ratio of antenna or array
bandwidthCalculate and plot absolute bandwidth of antenna or array
beamwidthBeamwidth of antenna
chargeCharge distribution on antenna or array surface
currentCurrent distribution on antenna or array surface
designDesign prototype antenna or arrays for resonance around specified frequency or create AI-based antenna from antenna catalog objects
efficiencyCalculate and plot radiation efficiency of antenna or array
EHfieldsElectric and magnetic fields of antennas or embedded electric and magnetic fields of antenna element in arrays
feedCurrentCalculate current at feed for antenna or array
impedanceCalculate and plot input impedance of antenna or scan impedance of array
infoDisplay information about antenna, array, or platform
memoryEstimateEstimate memory required to solve antenna or array mesh
meshMesh properties of metal, dielectric antenna, or array structure
meshconfigChange meshing mode of antenna, array, custom antenna, custom array, or custom geometry
msiwriteWrite antenna or array analysis data to MSI planet file
optimizeOptimize antenna or array using SADEA optimizer
patternPlot radiation pattern and phase of antenna or array or embedded pattern of antenna element in array
patternAzimuthAzimuth plane radiation pattern of antenna or array
patternElevationElevation plane radiation pattern of antenna or array
peakRadiationCalculate and mark maximum radiation points of antenna or array on radiation pattern
rcsCalculate and plot monostatic and bistatic radar cross section (RCS) of platform, antenna, or array
resonantFrequencyCalculate and plot resonant frequency of antenna
returnLossCalculate and plot return loss of antenna or scan return loss of array
showDisplay antenna, array structures, shapes, or platform
sparametersCalculate S-parameters for antenna or array
stlwriteWrite mesh information to STL file
vswrCalculate and plot voltage standing wave ratio (VSWR) of antenna or array element

Examples

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Open Live Script

Create and view a top-hat monopole with 1 m length, 0.01 m width, groundplane dimensions 2mx2m and top hat dimensions 0.25mx0.25m.

th = monopoleTopHat
th = 
  monopoleTopHat with properties:

               Height: 1
                Width: 0.0100
    GroundPlaneLength: 2
     GroundPlaneWidth: 2
         TopHatLength: 0.2500
          TopHatWidth: 0.2500
            Substrate: [1x1 dielectric]
           FeedOffset: [0 0]
            Conductor: [1x1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]


show(th)

Figure contains an axes object. The axes object with title monopoleTopHat antenna element, xlabel x (m), ylabel y (m) contains 5 objects of type patch, surface. These objects represent PEC, feed.

Open Live Script

Calculate and plot the impedance of a top-hat monopole over a frequency range of 40 MHz-80 MHz. 

th = monopoleTopHat;
impedance(th,linspace(40e6,80e6,41));

Figure contains an axes object. The axes object with title Impedance, xlabel Frequency (MHz), ylabel Impedance (ohms) contains 2 objects of type line. These objects represent Resistance, Reactance.

Open Live Script

Impedance comparison between a monopole of similar dimensions and the top-hat monopole in example 2.

m = monopole;
figure
impedance(m,linspace(40e6,80e6,41));

Figure contains an axes object. The axes object with title Impedance, xlabel Frequency (MHz), ylabel Impedance (ohms) contains 2 objects of type line. These objects represent Resistance, Reactance.

Open Live Script

Create a top-hat monopole with default dimensions and a substrate with two dielectric layers.

mth = monopoleTopHat;
d = dielectric(Name={"FR4","Teflon"},Thickness=[0.5 0.5],LossTangent=[0.002 0.002],EpsilonR=[4.8 2.1]);
mth.Substrate = d
mth = 
  monopoleTopHat with properties:

               Height: 1
                Width: 0.0100
    GroundPlaneLength: 2
     GroundPlaneWidth: 2
         TopHatLength: 0.2500
          TopHatWidth: 0.2500
            Substrate: [1x1 dielectric]
           FeedOffset: [0 0]
            Conductor: [1x1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1x1 lumpedElement]

View the top-hat monopole antenna.

show(mth)

Figure contains an axes object. The axes object with title monopoleTopHat antenna element, xlabel x (m), ylabel y (m) contains 7 objects of type patch, surface. These objects represent PEC, feed, FR4, Teflon.

References

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

[2] Volakis, John. Antenna Engineering Handbook, 4th Ed. New York: Mcgraw-Hill, 2007.

Version History

Introduced in R2015a

See Also

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