Tilt CustomAntennaElement in Phased Array Toolbox

Hi there,

I am trying to tilt a custom made antenna element with the Phased Array toolbox for a radar simulation model I am working on. I am interested in rotating the actual antenna receiver as oposed to steering since I want the orientation of the antenna array to be different. Steering creates side lobes which I do not want.

The way I initialize my antenna element I use this:

antenna_element = phased.CustomAntennaElement('AzimuthAngles',-180:1:180,...
'ElevationAngles',-90:1:90,'MagnitudePattern',paramFMCW.magResponse,...
'PhasePattern',paramFMCW.phaseResponse);

Then I create my array using the same function in the tool box:

array = phased.ULA('Element',antenna_element,'NumElements',paramFMCW.elements,...
           'ElementSpacing',paramFMCW.lambda_coefficient*paramFMCW.lambda,'ArrayAxis','y');

Unfortunately, there is no tilt property in this function, but there is one when using this linearArray function. Since I thought it passes on an antenna object, I have used the following syntax to create the array:

       my_custom_tilted_linear_array = linearArray('NumElements',paramFMCW.elements,...
          'ElementSpacing',paramFMCW.lambda_coefficient*paramFMCW.lambda,'TiltAxis',[1 0 0]);

But I get the following error:

Error using phased.CustomAntennaElement/parenReference

Not enough input arguments. Expected 2 (in addition to System object), got 1.

Error in radar_simulation (line 117)

my_linear_array =

linearArray('Element',antenna_element,'NumElements',paramFMCW.elements,... -

Show complete stack trace

Displaying stack trace:

Error using em.MeshGeometry.checkObjectClass

• In em.MeshGeometry.checkObjectClass

• In em.Array.setElementAsScalarHandle

• In em.ArrayProp>ArrayProp.set.Element (line 61)

• In em.ArrayProp>ArrayProp.ArrayProp (line 30)

• In linearArray>linearArray.linearArray (line 87)

• In radar_simulation (line 117)

There is the option of tilting my custom antenna element in CST and then importing it again in MATLAB, but I think there should be a programmatical way of tilting the element in the Phased Array toolbox.

Any suggestions?

[Cristian Alistarh]

Just an update: tilting the antenna element in CST does not tilt the array in MATLAB the way I wanted, since it beamforms differently. So in order that I can provide the array for the Delay and Sum Beamformer I have to create the array.

So I think there is no other option at the moment but tilt the receiver programmatically.

[Navya Seelam]

Hi,

Can you further elaborate on your use case? Are you trying to change the pattern or the orientation of the beam?

[Cristian Alistarh]

Hi there,

Thanks for your reply.

I am trying to change the orientation of the beam produced by the array without steering. Steering will be done later but conceptually I am trying to obtain this in MATLAB.

So I have the custom element, and then produce the array. But then I want to tilt the custom array which I have produced and I do not know how this is done in Matlab.

Thanks in advance!

All the best,

Cristian

Answer 1

[Cristian Alistarh]

I think I have managed to answer my own question. Please free to comment if you think different.

So what to do in MATLAB is to use the conformal array object from the tool box and position the elements at the positions you wish. You can also specify the direction of the normals which also needed for the example I am doing.

I think the element normals can be done a bit better but here it is:

numberOfElements = 4; 
lambda = 3e8/24e9;
total_array_size = numberOfElements * lambda/2 ;


pos_y =  [0 0 0 0];
pos_x = [-0.75*lambda -0.25*lambda 0.25*lambda 0.75*lambda];


sector1_pos_vector = [pos_x+2*lambda;pos_y]';

theta = 60; 
R=[cos(theta) -sin(theta); sin(theta) cos(theta)]; 

pos_vector_new = sector1_pos_vector * R';

N = 3* length(pos_y);

sCA = phased.ConformalArray(...
    'ElementPosition',[pos_vector_new(:,1)' pos_x -pos_vector_new(:,1)' ;pos_vector_new(:,2)' total_array_size*pos_y-lambda/4 pos_vector_new(:,2)';zeros(1,N)],...
    'ElementNormal',[pos_vector_new(:,2)' pos_y pos_vector_new(:,2)';zeros(1,N)]);

viewArray(sCA);

Now this should give you something like this:

I think this should be fine for the example I am investigating. Thanks. I look forward to any comments you might have.