getElementNormal

Normal vectors for array elements

Syntax

``normvec = getElementNormal(array)``
``normvec = getElementNormal(array,elemidx)``

Description

example

````normvec = getElementNormal(array)` returns the normal vectors `normvec` to the `array`.```
``` `normvec = getElementNormal(array,elemidx)` returns only the normals of the elements that are specified in the element index vector `elemidx`.```

Examples

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Construct three ULAs with elements along the x-, y-, and z-axes. Obtain the element normals.

First, choose the array axis along the x-axis.

```sULA1 = phased.ULA('NumElements',5,'ArrayAxis','x'); norm = getElementNormal(sULA1)```
```norm = 2×5 90 90 90 90 90 0 0 0 0 0 ```

The element normal vectors point along the y-axis.

Next, choose the array axis along the y-axis.

```sULA2 = phased.ULA('NumElements',5,'ArrayAxis','y'); norm = getElementNormal(sULA2)```
```norm = 2×5 0 0 0 0 0 0 0 0 0 0 ```

The element normal vectors point along the x-axis.

Finally, set the array axis along the z-axis. Obtain the normal vectors of the odd-numbered elements.

```sULA3 = phased.ULA('NumElements',5,'ArrayAxis','z'); norm = getElementNormal(sULA3,[1,3,5])```
```norm = 2×3 0 0 0 0 0 0 ```

The element normal vectors also point along the x-axis.

Input Arguments

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Phased array, specified as a System object.

Element index vector, specified as a vector of positive integers each of which takes a value from 1 to N. The dimension N is the number of elements of the array.

Example: `[1,2,3]`

Output Arguments

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Normal vector of array elements, returned as a 2-by-M real matrix. Each column of `normvec` specifies the normal direction of the corresponding element in the local coordinate system in the form `[azimuth;elevation]`. If the input argument `elemidx` is not specified, M is the number of elements of the array, N. If `elemidx` is specified, M is the size of `elemidx`. The azimuth angle is defined as the angle from x-axis toward y axis. The elevation angle is defined as the angle from xy-plane toward z-axis. Units are in degrees.

For uniform linear arrays, the normal vector depends upon the value of the `ArrayAxis` property.

ArrayAxis Property ValueArray Normal Direction
`'x'`azimuth = 90°, elevation = 0° (y-axis)
`'y'`azimuth = 0°, elevation = 0° (x-axis)
`'z'`azimuth = 0°, elevation = 0° (x-axis)
• For a conformal array, the origin of the local coordinate system, i.e., the phase center of the array, is defined at an arbitrary point. In local coordinate system, x, y, and z axes are three orthogonal axes with x axis defines the normal direction of the conformal array. The elements are located in the 3D space.

Version History

Introduced in R2021a