About phased array design

How to create transmit antenna arrays with different lambda values and shifted in the up direction? A sample array design is given below, the linear array has 2 lambda between TX and shifted ones have 0.5 lambda.

Answer 1

[Sivapriya Srinivasan]

Hello,

To create a transmit antenna array with different lambda values and shifted in the up direction, you can follow these steps:

1.Open a new MATLAB script or function and define the parameters of your antenna array. For example, you can define the number of elements in the array, the spacing between elements, and the wavelength of the signal.

2.Create a linear antenna array with the desired number of elements and spacing. You can use the "linearArray" function in the phased array toolbox to create this array.

3.Define the positions of the shifted elements in the array. To shift the elements in the up direction, you can add a positive offset to the y-coordinate of the element positions. For example, if you want to shift the elements by 0.5 lambda, you can add 0.5 times the element spacing to the y-coordinate of the positions.

4.Create a new antenna array object with the shifted element positions. You can use the "phased.CustomAntennaElement" function to create a custom antenna element with the desired position.

5.Combine the linear and shifted antenna arrays into a single array object using the "phased.ConformalArray" function. This function allows you to create an array with arbitrary element positions and orientations.

6.Set the direction of the main beam of the antenna array using the "phased.SteeringVector" function. This function allows you to specify the direction of the main beam using azimuth and elevation angles.

7.Generate a plot of the antenna array using the "pattern" function. This function generates a 3D plot of the radiation pattern of the antenna array.

Here is some sample code that demonstrates how to create a transmit antenna array with different lambda values and shifted in the up direction:

% Define the parameters of the antenna array

numElements = 8; % Number of elements in the array

elementSpacing = 0.5; % Spacing between elements in wavelengths

wavelength = 1; % Wavelength of the signal

% Create a linear antenna array

linearArray = phased.LinearArray('NumElements', numElements, 'ElementSpacing', elementSpacing);

% Define the positions of the shifted elements

shiftedPositions = linearArray.getElementPosition() + [0; 0.5*elementSpacing; 0];

% Create a custom antenna element with the shifted position

shiftedElement = phased.CustomAntennaElement('Position', shiftedPositions);

% Create a conformal array with the linear and shifted elements

conformalArray = phased.ConformalArray('ElementPosition', [linearArray.getElementPosition(), shiftedPositions],...

'Element', [linearArray.getElement(), shiftedElement]);

% Set the direction of the main beam of the array

azimuthAngle = 30; % Azimuth angle of the main beam in degrees

elevationAngle = 0; % Elevation angle of the main beam in degrees

steeringVector = phased.SteeringVector('SensorArray', conformalArray, 'PropagationSpeed', physconst('LightSpeed'));

conformalArray.ElementPhase = steeringVector(azimuthAngle, elevationAngle);

% Generate a plot of the radiation pattern of the array

pattern(conformalArray, wavelength, -180:180, 0, 'CoordinateSystem', 'polar');

This code creates a transmit antenna array with 8 elements, where the first 4 elements are arranged in a linear array with 2 lambda spacing and the last 4 elements are shifted up by 0.5 lambda. The direction of the main beam is set to 30 degrees azimuth and 0 degrees elevation, and a radiation pattern plot is generated.

You can also refer to this documentation for further assistance:Phased Array Design and Analysis - MATLAB & Simulink (mathworks.com)

Hope this Helps!

[Deniz Kumlu]

Hi Sivapriya,

Thanks for the quick response, I did not run the code that you shared but I saw similar implementation on "https://www.mathworks.com/help/radar/ug/generating-and-processing-radar-iq-data-using-radartransceiver.html".

Thus, I created the conformal array as it described. I just wonder one point related to the below code in ""

Design and Simulate an FMCW Long-Range Radar (LRR)

" functions, they said each array element modeled as a 4-element series-fed patch antenna but I could not see any line to create this microstrip antenna?

# This is the code block from "helperDesignArray.m" funcion:

% Create the transmit array designed in [1] consisting of 12 array elements

% with each array element modeled as a 4-element series-fed patch antenna.

txPos = zeros(33,7);

txPos(1:4:end,1) = 1;

txPos(10,2) = 1;

txPos(11,5) = 1;

txPos(12,7) = 1;

[row,col] = ind2sub(size(txPos),find(txPos(:)));

txArray = phased.ConformalArray('Element',ant,'ElementPosition',[zeros(numel(row),1) row-1 col-1]'*lambda/2);

[Deniz Kumlu]

Hi Sivapriya,

In MATLAB inbulilt function, It is given that each array element modeled as a 4-element series-fed patch antenna but I could not see any line to create this microstrip antenna?

Can you please help me for this part?

Thanks.