step

System object: phased.UCA
Package: phased

Output responses of array elements

Syntax

RESP = step(sArray,FREQ,ANG)

Description

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.

RESP = step(sArray,FREQ,ANG) returns the responses, 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 (MATLAB) 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

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Uniform circular array, specified as a phased.UCA System object.

Example: sArray= phased.UCA;

Operating frequency of array specified, specified as a positive scalar or 1-by-L real-valued row vector. Frequency units are in hertz.

  • For antenna or microphone elements, FREQ must lie within the range of values specified by the FrequencyRange or FrequencyVector property of the element. Otherwise, the element produces no response and the array response is returned as zero. Most elements use the FrequencyRange property except for phased.CustomAntennaElement and phased.CustomMicrophoneElement, which use the FrequencyVector property.

  • For an array of elements, FREQ must lie within the frequency range of the elements that make up the array. Otherwise, the array produces no response and the directivity is returned as zero.

Example: [1e8 2e8]

Data Types: double

Response directions, specified as either a 2-by-M real-valued matrix or a real-valued 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 lie between –180° and 180°, inclusive. The elevation angle must lie between –90° and 90°, inclusive. Angle units are in degrees.

If ANG is a row vector of length M, each element specifies the azimuth angle of the direction. In this case, the corresponding elevation angle is assumed to be 0°.

Example: [20;15]

Data Types: double

Output Arguments

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Voltage responses of a phased array, specified as a complex-valued matrix or a struct with complex-valued fields. The output depends on whether the array supports polarization or not.

  • If the array elements do not support polarization, the voltage response, RESP, has the dimensions N-by-M-by-L.

    • N (rows) is the number of elements in the array

    • M (columns) is the number of angles specified in ANG

    • L (pages) is the number of frequencies specified in FREQ

    For each array element, the columns of RESP contain the array element responses for the corresponding direction specified in ANG. Each of the L pages of RESP contains the array element responses for the corresponding frequency specified in FREQ.

  • If the array supports polarization, RESP is a MATLAB struct containing two fields, RESP.H and RESP.V. The field, RESP.H, represents the array’s horizontal polarization response, while RESP.V represents the array’s vertical polarization response. Each field has the dimensions N-by-M-by-L.

    • N (rows) is the number of elements in the array

    • M (columns) is the number of angles specified in ANG

    • L (pages) is the number of frequencies specified in FREQ

    For each array element, the columns of RESP.H or RESP.V contain the array element responses for the corresponding direction specified in ANG. Each of the L pages of RESP.H or RESP.V contains the array element responses for the corresponding frequency specified in FREQ.

Examples

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Create a 5-element uniform circular array (UCA) of cosine antenna elements having a 0.5 meter radius. Find the element responses at the 0 degrees azimuth and elevation at a 300 MHz operating frequency.

c = physconst('LightSpeed');
fc = 300e6;
sCos = phased.CosineAntennaElement('CosinePower',[1,1]);
sArray = phased.UCA('Element',sCos,'NumElements',5,'Radius',0.5);
ang = [0;0];
resp = step(sArray,fc,ang)
resp = 5×1

         0
    0.3090
    1.0000
    0.3090
         0

Introduced in R2015a