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

The `dipoleHelixMultifilar`

object creates a balanced bifilar
or quadrafilar helix antenna without a circular ground plane. 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

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

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.

creates a bifilar or quadrafilar helix antenna without a circular ground
plane. The default multifilar helical antenna is end-fed. The default helix
operates around 2 GHz.`ant`

= dipoleHelixMultifilar

sets properties using one or more name-value pairs. For example,
`ant`

= dipoleHelixMultifilar(Name,Value)`ant = dipoleHelixMultifilar('Radius',28e-03)`

creates
a multifilar helix with turns of radius
`28e`

m. Enclose each
property name in quotes.^{-03}

`show` | Display antenna or array structure; display shape as filled patch |

`axialRatio` | Axial ratio of antenna |

`beamwidth` | Beamwidth of antenna |

`charge` | Charge distribution on metal or dielectric antenna or array surface |

`current` | Current distribution on metal or dielectric antenna or array surface |

`design` | Design prototype antenna or arrays for resonance around specified frequency |

`efficiency` | Radiation efficiency of antenna |

`EHfields` | Electric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays |

`impedance` | Input impedance of antenna; scan impedance of array |

`mesh` | Mesh properties of metal or dielectric antenna or array structure |

`meshconfig` | Change mesh mode of antenna structure |

`optimize` | Optimize antenna or array using SADEA optimizer |

`pattern` | Radiation pattern and phase of antenna or array; Embedded pattern of antenna element in array |

`patternAzimuth` | Azimuth pattern of antenna or array |

`patternElevation` | Elevation pattern of antenna or array |

`rcs` | Calculate and plot radar cross section (RCS) of platform, antenna, or array |

`returnLoss` | Return loss of antenna; scan return loss of array |

`sparameters` | Calculate S-parameter for antenna and antenna array objects |

`vswr` | Voltage standing wave ratio of antenna |