Documentation

# dipole

Create strip dipole antenna

## Description

The `dipole` object is a strip dipole antenna on the Y-Z 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 equivalent cylindrical dipole.

• r is the radius of equivalent cylindrical dipole.

For a given cylinder radius, use the `cylinder2strip` utility function to calculate the equivalent width. The default strip dipole is center-fed. The feed point coincides with the origin. The origin is located on the Y-Z plane.

## Creation

### Syntax

``d = dipole``
``d = dipole(Name,Value)``

### Description

``` `d = dipole` creates a half-wavelength strip dipole antenna on the Y-Z plane.```

example

``` `d = dipole(Name,Value)` creates a 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 you do not specify retains their default values.```

## Properties

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Dipole length, specified as a scalar in meters. By default, the length is chosen for an operating frequency of 75 MHz.

Example: `'Length',3`

Data Types: `double`

Dipole width, specified as a scalar in meters.

### Note

Dipole width should be less than `'Length'`/5 and greater than `'Length'`/1001. [2]

Example: `'Width',0.05`

Data Types: `double`

Signed distance from center of dipole, specified as a scalar in meters. The feed location is on Y-Z plane.

Example: `'FeedOffset',3`

Data Types: `double`

Lumped elements added to the antenna feed, specified as 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: ```d.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 dipole with 2m length and 0.5m width.

`d = dipole('Width',0.05)`
```d = dipole with properties: Length: 2 Width: 0.0500 FeedOffset: 0 Tilt: 0 TiltAxis: [1 0 0] Load: [1x1 lumpedElement] ```
`show(d)`

Calculate the impedance of a dipole over a frequency range of 50MHz - 100MHz.

```d = dipole('Width',0.05); impedance(d,linspace(50e6,100e6,51))```

Design a dipole antenna backed by a dielectric substrate and an infinite reflector.

Create a dipole antenna of length, 0.15 m, and width, 0.015 m.

`d = dipole('Length',0.15,'Width',0.015, 'Tilt',90,'TiltAxis',[0 1 0]);`

Create a reflector using the dipole antenna as an exciter and the dielectric, `teflon` as the substrate.

`t = dielectric('Teflon')`
```t = dielectric with properties: Name: 'Teflon' EpsilonR: 2.1000 LossTangent: 2.0000e-04 Thickness: 0.0060 For more materials see catalog ```
`rf = reflector('Exciter',d,'Spacing',7.5e-3,'Substrate',t);`

Set the groundplane length of the reflector to `inf`. View the structure.

```rf.GroundPlaneLength = inf; show(rf)```

Calculate the radiation pattern of the antenna at 70 MHz.

`pattern(rf,70e6)`

## 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.