# 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:

Create the

`phased.UCA`

object and set its properties.Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

## Creation

### Syntax

### Description

`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

## Usage

### Syntax

### Description

returns the responses, `RESP`

= sUCA(`FREQ`

,`ANG`

)`RESP`

, of the array elements, at
operating frequencies specified in `FREQ`

and directions
specified in `ANG`

.

**Note**

The object performs an initialization the first time the object is executed. This
initialization locks nontunable properties
and input specifications, such as dimensions, complexity, and data type of the input data.
If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first
call the `release`

method to unlock the object.

### Input Arguments

### Output Arguments

## Object Functions

To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named `obj`

, use
this syntax:

release(obj)

## 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

## Version History

**Introduced in R2015a**

## See Also

`phased.URA`

| `phased.ULA`

| `phased.ConformalArray`

| `phased.CosineAntennaElement`

| `phased.CrossedDipoleAntennaElement`

| `phased.CustomAntennaElement`

| `phased.IsotropicAntennaElement`

| `phased.ShortDipoleAntennaElement`

| `phased.CustomMicrophoneElement`

| `phased.OmnidirectionalMicrophoneElement`