dipoleHelixMultifilar

Create balanced bifilar or quadrafilar dipole helix antenna without circular ground plane

Description

The default dipoleHelixMultifilar object creates a balanced bifilar or quadrafilar helix antenna without a circular ground plane resonating around 1.56 GHz. You can create both short-circuited and open-ended dipole helix multifilar antennas. Bifilar and quadrafilar helix antennas are used in aerospace and defense applications.

The width of the strip is related to the diameter of an equivalent cylinder by the equation

$$w=2d=4r$$

where:

• w is the width of the strip.

• d is the diameter of an equivalent cylinder.

• r is the radius of an equivalent cylinder.

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. The default helix antenna is end-fed. The circular ground plane is on the xy- plane. Helix antennas are used commonly in axial mode. In this mode, the helix circumference is comparable to the operating wavelength, and the helix has maximum directivity along its axis. In normal mode, the helix radius is small compared to the operating wavelength. In this mode, the helix radiates broadside, that is, in the plane perpendicular to its axis. The basic equations for the helix are

$$\begin{array}{l}x=r\cos (\theta )\\ y=r\sin (\theta )\\ z=S\theta \end{array}$$

where:

• r is the radius of the helical dipole.

• θ is the winding angle.

• S is the spacing between turns.

For a given pitch angle in degrees, use the helixpitch2spacing utility function to calculate the spacing between the turns in meters.

Creation

Syntax

ant = dipoleHelixMultifilar

ant = dipoleHelixMultifilar(PropertyName=Value)

Description

ant = dipoleHelixMultifilar creates an end-fed bifilar or quadrafilar helix antenna without a circular ground plane with default property values. The default dimensions are chosen for an operating frequency of around 1.56 GHz.

ant = dipoleHelixMultifilar(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, ant = dipoleHelixMultifilar(Radius=28e-03) creates a multifilar helix with turns of radius 28e-03 m.

Properties

NumArms — Number of helical elements

4 (default) | 2

Number of helical elements, specified as a 4 or 2. Two elements create a bifilar dipole helix antenna, and four elements create a quadrafilar dipole helix antenna.

Example: 2

Data Types: double

Radius — Radius of turns

0.0220 (default) | positive real scalar

Radius of the turns, specified as a positive real scalar meter.

Example: 28e-03

Data Types: double

Width — Width of strip

1.000e-03 (default) | positive real scalar

Width of the strip, specified as a positive real scalar in meters.

Example: 0.2

Data Types: double

Turns — Number of turns

3 (default) | scalar integer

Number of turns, specified as a scalar integer.

Example: 4

Data Types: double

Spacing — Spacing between turns

0.0350 (default) | positive real scalar

Spacing between the turns, specified as a positive real scalar in meters.

Example: 7.5e-2

Data Types: double

ShortEnds — Status of ends of helix

1 (default) | 0

Status of ends of the helix, specified as 0 or 1. By default, the dipoleHelixMultifilar is short circuited. Setting the property to 0 makes the helix antenna an open circuit.

Example: 0

Data Types: double

WindingDirection — Direction of helix turns (windings)

"CCW" (default) | "CW"

Direction of helix turns (windings), specified as CW or CCW.

Example: "CW"

Data Types: string

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 specify only one dielectric layer in the dipoleHelixMultifilar object. Specify the same radius for all the turns. When you use a dielectric material other than air, the number of turns in the dipole helix must be greater than 1. For a short-ended configuration, the number of turns must be a positive integer. For more information about dielectric substrate meshing, see Meshing.

Example: dielectric("Teflon")

Data Types: string

Conductor — Type of metal

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

Default Multifilar Helical Dipole Antenna

Create and view a default multifilar helical dipole antenna.

ant = dipoleHelixMultifilar

ant = 
  dipoleHelixMultifilar with properties:

             NumArms: 4
              Radius: 0.0220
               Width: 1.0000e-03
               Turns: 3
             Spacing: 0.0350
           ShortEnds: 1
    WindingDirection: 'CCW'
           Substrate: [1×1 dielectric]
           Conductor: [1×1 metal]
                Tilt: 0
            TiltAxis: [1 0 0]
                Load: [1×1 lumpedElement]

show(ant)

Quadrafilar Helical Dipole Antenna and Radiation Pattern

Create and view a quadrafilar helical dipole antenna with turn radius of 22 mm and strip width of 1 mm.

ant = dipoleHelixMultifilar(Radius=22e-3,Width=1e-3);

Add a Teflon dielectric substrate to it.

d = dielectric("Teflon");
ant.Substrate = d;
show(ant)

Plot the radiation pattern of the helical dipole at 1.56 GHz.

pattern(ant,1.56e9);

Version History

Introduced in R2018b