# step

System object: phased.CosineAntennaElement
Package: phased

Output response of antenna element

## Syntax

`RESP = step(H,FREQ,ANG)`

## Description

`RESP = step(H,FREQ,ANG)` returns the antenna's voltage response `RESP` at operating frequencies specified in `FREQ` and directions specified in `ANG`.

 Note:   The object performs an initialization the first time the `step` method 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

 `H` Antenna element object. `FREQ` Operating frequencies of antenna in hertz. `FREQ` is a row vector of length L. `ANG` Directions in degrees. `ANG` can be either a 2-by-M matrix or a row vector of length M. If `ANG` is a 2-by-M matrix, each column of the matrix specifies the direction in the form [azimuth; elevation]. The azimuth angle must be between –180 and 180 degrees, inclusive. The elevation angle must be between –90 and 90 degrees, inclusive. If `ANG` is a row vector of length M, each element specifies a direction's azimuth angle. In this case, the corresponding elevation angle is assumed to be 0.

## Output Arguments

 `RESP` Voltage response of antenna element specified as an M-by-L, complex-valued matrix. In this matrix, M represents the number of angles specified in `ANG` while L represents the number of frequencies specified in `FREQ`.

## Definitions

### Cosine Response

The cosine response, or cosine pattern, is given by:

`$P\left(az,el\right)={\mathrm{cos}}^{m}\left(az\right){\mathrm{cos}}^{n}\left(el\right)$`

In this expression:

• az is the azimuth angle.

• el is the elevation angle.

• The exponents m and n are real numbers greater than or equal to 1.

The response is defined for azimuth and elevation angles between –90 and 90 degrees, inclusive. There is no response at the back of a cosine antenna. The cosine response pattern achieves a maximum value of 1 at 0 degrees azimuth and elevation. Raising the response pattern to powers greater than one concentrates the response in azimuth or elevation.

## Examples

Construct a cosine antenna element. The cosine response is raised to a power of 1.5. The antenna frequency range is the IEEE® X band from 8 to 12 GHz. The antenna operates at 10 GHz. Obtain the antenna's response for an incident angle of 30 degrees azimuth and 5 degrees elevation.

```hant = phased.CosineAntennaElement(... 'FrequencyRange',[8e9 12e9],... 'CosinePower',1.5); % operating frequency fc = 10e9; % incident angle ang = [30;5]; % use the step method to obtain the antenna's response resp = step(hant,fc,ang);```