# phased.UCA

Uniform circular array

## Description

The `phased.UCA`

System object™ creates a *uniform circular array* (UCA). A UCA is
formed from identical sensor elements equally spaced around a circle.

To compute the response for the array for specified directions:

Define and set up your uniform circular array. See Construction.

Call

`step`

to compute the response according to the properties of`phased.UCA`

. The behavior of`step`

is specific to each object in the toolbox.

**Note**

Starting in R2016b, instead of using the `step`

method to perform the operation defined by the System object, you can call the object with arguments, as if it were a function. For
example, `y = step(obj,x)`

and `y = obj(x)`

perform equivalent operations.

## Construction

`sUCA = phased.UCA`

creates a uniform circular array (UCA)
System object, `sUCA`

, consisting of five identical isotropic antenna
elements,`phased.IsotropicAntennaElement`

. The elements
are equally spaced around a circle of radius 0.5 meters.

`sUCA = phased.UCA(`

creates a System object, `Name`

,`Value`

)`sUCA`

, with each specified property Name set to the
specified Value. You can specify additional name-value pair arguments in any order as
(`Name1,Value1`

,...,`NameN,ValueN`

).

`sUCA = phased.UCA(`

creates a UCA System object, `N`

,`R`

)`sUCA`

, with the `NumElements`

property set to `N`

and the `Radius`

property set
to `R`

. This syntax creates a UCA consisting of isotropic antenna
elements, `phased.IsotropicAntennaElement`

.

`sUCA = phased.UCA(`

creates a UCA System object, `N`

,`R`

,`Name,Value`

)`sUCA`

, with the `NumElements`

property set to `N`

, the `Radius`

property set to
`R`

, and other specified property Names set to the specified
Values.

## Properties

## Methods

Specific to
`phased.URA` Object | |
---|---|

`beamwidth` | Compute and display beamwidth of an array |

`collectPlaneWave` | Simulate received plane waves |

`directivity` | Directivity of uniform circular array |

`getElementNormal` | Normal vectors for array elements |

`getElementPosition` | Positions of array elements |

`getElementSpacing` | Spacing between array elements |

`getNumElements` | Number of elements in array |

`getTaper` | Array element tapers |

`isPolarizationCapable` | Polarization capability |

`pattern` | Plot UCA array pattern |

`patternAzimuth` | Plot UCA array directivity or pattern versus azimuth |

`patternElevation` | Plot UCA array directivity or pattern versus elevation |

`step` | Output responses of array elements |

`viewArray` | View array geometry |

Common to All System Objects | |
---|---|

`release` | Allow System object property value changes |

## Examples

## Algorithms

A UCA is formed from *N* identical sensor elements equally spaced
around a circle of radius *R*. The circle lies in the
*xy*-plane of the local coordinate system whose origin lies at the
center of the circle. The positions of the elements are defined with respect to the
local array coordinate system. The circular array lies in the
*xy*-plane of the coordinate system. The normal to the UCA plane lies
along the positive *z*-axis. The elements are oriented so that their
main response directions (normals) point radially outward in the *xy*-plane.

If the number of elements of the array is odd, the middle element lies on the
*x*-axis. If the number of elements is even, the midpoint between
the two middle elements lies on the *x*-axis. For an array of
*N* elements, the azimuth angle of the position of the
*nth* element is given by

$${\phi}_{n}=(-(N-1)/2+n-1)\cdot 360/N\text{}n=1,\dots ,N$$

The azimuth angle is defined as the angle, in the
*xy*-plane, from the *x*-axis toward the
*y*-axis. The elevation angle is defined as the angle from the
*xy*-plane toward the *z*-axis. The angular
distance between any two adjacent elements is *360/N* degrees. Azimuth
angle values are in degrees. Elevation angles for all array elements are zero.

## References

[1] Brookner, E., ed. *Radar Technology*. Lexington, MA:
LexBook, 1996.

[2] Van Trees, H. *Optimum Array Processing*. New York:
Wiley-Interscience, 2002, pp. 274–304.

## Extended Capabilities

## See Also

`phased.ULA`

| `phased.URA`

| `phased.ConformalArray`

| `phased.CosineAntennaElement`

| `phased.CrossedDipoleAntennaElement`

| `phased.CustomAntennaElement`

| `phased.IsotropicAntennaElement`

| `phased.ShortDipoleAntennaElement`

| `phased.CustomMicrophoneElement`

| `phased.OmnidirectionalMicrophoneElement`

### Topics

**Introduced in R2015a**