monopoleTopHat

Create capacitively loaded monopole antenna over rectangular ground plane

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(PropertyName=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.

mth = monopoleTopHat(PropertyName=Value) sets properties using one or more name–value arguments. PropertyName is the property name and Value is the corresponding value. You can specify several name-value arguments in any order as PropertyName1=Value1,...,PropertyNameN=ValueN. Properties that you do not specify, retain their default values.

For example, mth = monopoleTopHat(Height=2) creates a top-hat monopole antenna of 2 m height.

Properties

Height — Monopole height

1 (default) | scalar

Monopole height, specified as a scalar in meters.

Example: 3

Data Types: double

Width — Monopole width

0.1000 (default) | scalar

Monopole width, specified as a scalar in meters.

Note

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

Example: 0.05

Data Types: double

GroundPlaneLength — Ground plane length along x-axis

2 (default) | scalar

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: 4

Data Types: double

GroundPlaneWidth — Ground plane width along y-axis

2 (default) | scalar

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: 2.5

Data Types: double

TopHatLength — Top hat length along x-axis

0.2500 (default) | scalar

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

Example: 4

Data Types: double

TopHatWidth — Top hat width along y-axis

0.2500 (default) | scalar

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

Example: 4

Data Types: double

FeedOffset — Signed distance from center along length and width of ground plane

[0 0] (default) | two-element vector

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

Example: [2 1]

Data Types: double

Substrate — Type of dielectric material

dielectric("Air") (default) | dielectric object

Type of dielectric material used as a substrate, specified as a dielectric object. You can choose any dielectric material from the DielectricCatalog or specify a dielectric material of your choice. You can also specify multiple dielectric layers. When creating multiple dielectric layers, specify the name, thickness, loss tangent, and relative permittivity of each layer. The substrate dimensions must be equal to the ground plane dimensions. For more information on dielectric substrate meshing, see Meshing.

Example: dielectric("FR4")

Example: dielectric(Name={"FR4","Teflon"},Thickness=[0.5 0.5],LossTangent=[0.002 0.002],EpsilonR=[4.8 2.1])

Conductor — Type of metal material

metal("PEC") (default) | metal object

Type of the metal used as a conductor, specified as a metal object. You can choose any metal from the MetalCatalog or specify a metal of your choice. For more information on metal conductor meshing, see Meshing.

Example: metal("Copper")

Load — Lumped elements

[1x1 lumpedElement] (default) | lumpedElement object

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

Example: lumpedElement(Impedance=75)

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

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

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector | 2-by-3 matrix | "X" | "Y" | "Z"

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

axialRatio	Calculate and plot axial ratio of antenna or array
bandwidth	Calculate and plot absolute bandwidth of antenna or array
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
current	Current distribution on antenna or array surface
design	Create antenna, array, or AI-based antenna resonating at specified frequency
efficiency	Calculate and plot radiation efficiency of antenna or array
EHfields	Electric and magnetic fields of antennas or embedded electric and magnetic fields of antenna element in arrays
feedCurrent	Calculate current at feed for antenna or array
impedance	Calculate and plot input impedance of antenna or scan impedance of array
info	Display information about antenna, array, or platform
memoryEstimate	Estimate memory required to solve antenna or array mesh
mesh	Generate and view mesh for antennas, arrays, and custom shapes
meshconfig	Change meshing mode of antenna, array, custom antenna, custom array, or custom geometry
msiwrite	Write antenna or array analysis data to MSI planet file
optimize	Optimize antenna and array catalog elements using SADEA or TR-SADEA algorithm
pattern	Plot radiation pattern of antenna, array, or embedded element of array
patternAzimuth	Azimuth plane radiation pattern of antenna or array
patternElevation	Elevation plane radiation pattern of antenna or array
peakRadiation	Calculate and mark maximum radiation points of antenna or array on radiation pattern
rcs	Calculate and plot monostatic and bistatic radar cross section (RCS) of platform, antenna, or array
resonantFrequency	Calculate and plot resonant frequency of antenna
returnLoss	Calculate and plot return loss of antenna or scan return loss of array
show	Display antenna, array structures, shapes, or platform
sparameters	Calculate S-parameters for antenna or array
stlwrite	Write mesh information to STL file
vswr	Calculate and plot voltage standing wave ratio (VSWR) of antenna or array element

Examples

Create and View Top-Hat Monopole

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: [1×1 dielectric]
           FeedOffset: [0 0]
            Conductor: [1×1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1×1 lumpedElement]

show(th)

Calculate Impedance of Top-Hat Monopole Antenna

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));

Compare Impedance of Top-Hat Monopole Antenna and Monopole Antenna

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));

Top-Hat Monopole with Multiple Dielectric Layers

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: [1×1 dielectric]
           FeedOffset: [0 0]
            Conductor: [1×1 metal]
                 Tilt: 0
             TiltAxis: [1 0 0]
                 Load: [1×1 lumpedElement]

View the top-hat monopole antenna.

show(mth)

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