Documentation

# dipoleFolded

Create folded dipole antenna

## Description

The `dipolefolded` object is a folded dipole antenna on the X-Y plane.

The width of the dipole is related to the diameter of an equivalent cylindrical dipole by the equation

`$w=2d=4r$`

, where

• d is the diameter of the equivalent cylindrical pole

• r is the radius of the equivalent cylindrical pole.

For a given cylinder radius, use the `cylinder2strip` utility function to calculate the equivalent width. The default folded dipole is center-fed. The feed point of the dipole coincides with the origin. The origin is located on the X-Y plane. When compared to the planar `dipole`, the folded dipole structure increases the input impedance of the antenna.

## Creation

### Syntax

``dF = dipoleFolded``
``dF = dipoleFolded(Name,Value)``

### Description

``` `dF = dipoleFolded` creates a half-wavelength folded dipole antenna.```

example

``` `dF = dipoleFolded(Name,Value)` creates a half-wavelength folded dipole 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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Folded dipole length, specified as a scalar in meters. By default, the length is chosen for an operating frequency of 70.5 MHz.

Example: `'Length',3`

Data Types: `double`

Folded dipole width, specified as a scalar in meters.

### Note

Folded dipole width should be less than `'Length'`/20 and greater than `'Length'`/1001. [2]

Example: `'Width',0.05`

Data Types: `double`

Shorting stub lengths at dipole ends, specified as a scalar in meters. The value must be less than `Length`/50.

Example: `'Spacing',3`

Data Types: `double`

Lumped elements added to the antenna feed, specified a lumped element object handle. For more information, see `lumpedElement`.

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

Example: ```dF.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: `'Tilt',[90 90]`,`'TiltAxis',[0 1 0;0 1 1]` tilts the antenna at 90 degree about two axes, defined by vectors.

Data Types: `double`

Tilt axis of the antenna, specified as:

• Three-element vectors of Cartesian coordinates in meters. In this case, each 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'.

Example: `'TiltAxis',[0 1 0]`

Example: `'TiltAxis',[0 0 0;0 1 0]`

Example: `ant.TiltAxis = 'Z'`

## Object Functions

 `show` Display antenna or array structure; Display shape as filled patch `info` Display information about antenna or array `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 at specified frequency `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 `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 `returnLoss` Return loss of antenna; scan return loss of array `sparameters` S-parameter object `vswr` Voltage standing wave ratio of antenna

## Examples

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Create and view a folded dipole with 2m length and 0.05m width.

`df = dipoleFolded('Length',2,'Width',0.05)`
```df = dipoleFolded with properties: Length: 2 Width: 0.0500 Spacing: 0.0245 Tilt: 0 TiltAxis: [1 0 0] Load: [1x1 lumpedElement] ```
`show(df)`

Plot the radiation pattern of a folded dipole at 70.5 MHz.

`df = dipoleFolded`
```df = dipoleFolded with properties: Length: 2 Width: 0.0180 Spacing: 0.0245 Tilt: 0 TiltAxis: [1 0 0] Load: [1x1 lumpedElement] ```
`pattern(df, 70.5e6);`

## 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.