Difference between steering and angle parameter!

What is the differencd between steer and Ang inputs of 'Narrowband tx array' block. According to my understanding Ang input is for radiating signal in that particular Angle direction e.g Azimuth 30

Then why steering is used if we can point the tx to different directions while using Different Angles?

Answer 1

[Honglei Chen]

The input 'Ang' specifies the direction at which the signal is transmitted.

The input 'Steer' only applies when you have a subarray in the block. So if you are not using a subarray, then you don't have to worry about it. The parameter is there because if you have a subarray, it is possible to steer subarrays via phase shifters and the parameter 'Steer' specifies which direction to specify those subarrays.

HTH

[Hassam Mahmood]

Okay so I can steer my beam by using 'Ang' only and directing my beam to scan a particular sector? For that I have to write a code in Function block or does phased array offer a built in block for scanning?

[Honglei Chen]

For scanning, you can turn on the weights at the transmit array which will steer the array. Ang should always be the direction where the signal transmitted to, i.e., where the target is located.

[Hassam Mahmood]

Okay thank you. I selected check box of weights input and there appears a port 'W'. What should be the value of W in order to steer beam from azimuth 0 to 45

[Hassam Mahmood]

And one more thing, I am still not clear about this scanning. If my Ang is set to target's location which is static in my case. And at the same time I am scanning through beam steering, so at any particular instance where my beam would be? If I set it at target's direction how is it going to scan the sector? Kindly elaborate

[Honglei Chen]

I responded a bit in the other thread. The W will be the conjugate of the steering vector at those angles. You can consider using MATLAB Function block to compute those weights and pass it into W.

Ang is the direction of signal propagation. Say you have a target, you want to compute the signal propagated toward that target regardless where the main beam is. The scanning can change where the beam point to, but it does not change where the target is, that's why Ang and beam direction may not be the same. If they happen to be the same, then you get the maximum power along that direction. Otherwise, you suffer a loss. Does this clarify things?

HTH

[Hassam Mahmood]

well I wrote a code to compute conjugate of steering vector at different angles but I had to predefine phased.URA again in order to pass the output to input port W of 'Narrowband tx array' block. Any possible solution to avoid this?

[Hassam Mahmood]

I am getting error of 'out of memory', my URA is 20by20 and here is the code for computing conjugate for input W . Kindly look into it

function y = fcn(signal)
coder.extrinsic('phased.URA', 'steervec');
y=zeros(400,1);
 az=45;
 fc=36e9;
 v=3e8;
 lambda=v/fc;
 siz_arr=(0:lambda/2:1.666666667)';

%  ss=phased.URA('Size',[20 20],'ElementSpacing' , lambda/2);
%  %arr=(0:lambda/2:
 elem_pos=(siz_arr/lambda);

   for le=1:1:az
       sv=steervec(elem_pos,le);
       complex_arr=conj(sv);
       y=complex_arr;
   end
    end

[Honglei Chen]

Could you let me know how you use it to get the out of memory error? Your code above errors out because your elem_pos dimension is wrong. Once I fixed it, I have no issue getting a result.

[Hassam Mahmood]

I used simulink blocks to simulate my model. Steps are as follows :

1) I transmitted 50000by1 signal to Function Block and Narrowband tx array block.

2) Narrowband tx array block has W port which is being fed by conjugate of vector array. Firstly I computed for 20by20 array but an error popped out saying 'expected dimensions to be 400by1. So when I changed my elem_pos array to 400by1 but got memory out error.

3) The output from Narrowband tx array is still 50000by1 which I don't know is correct or not?

4) On the receiving side I am using Rx narrowband array block and same Output from function block is being fed to Rx array input port of W. This port (W) is having dimensions of 400by1

Questions : How did you fix elem_pos dimensions?

And the procedures I mentioned, are they correct to scan my beam as I am using same W port values for Rx narrowband as well?

I hope I explained it fully, if not then I can attach my model