Plotting the beamwidth from a matrix

17 次查看（过去 30 天）
Aftab Ahmed Khan
Aftab Ahmed Khan 2014-9-5
评论： Chibuzo Nnonyelu 2017-2-23
Hi everyone, i have this given matrix (Elevation, azimuth & gain) in the attachment. How can i plot the 3db-beamwidth of this antenna pattern ? I just want to see the pattern and want to calculate the 3db-beamwidth. Thank you so much.
  3 个评论
显示 1更早的评论
Chibuzo Nnonyelu
Chibuzo Nnonyelu 2017-2-23
To calculate beamwidth, you need to have an idea of the mainlobe. In which direction does your mainlobe point in?

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Youssef Khmou
Youssef Khmou 2014-9-5
Another way to compute the beamwidth is to plot the azimuth and Gain :
Data=load('data_ABS_antenna_CASMA.mat');
X=Data.ABS_antenna_gain;
Gain=X(:,3);
Azimuth=X(:,2);
[index,c]=find(Gain>=max(Gain)-3);
figure; plot(Azimuth(index),Gain(index),'*')
figure; plot(Azimuth,Gain,'*')
The beamwidth is 20° .

更多回答（2 个）

Star Strider
Star Strider 2014-9-5
Seeing the pattern is relatively easy, at least with the data available:
Ant = load('data_ABS_antenna_CASMA.mat');
Az = Ant.ABS_antenna_gain(:,1);
El = Ant.ABS_antenna_gain(:,2);
Gn = Ant.ABS_antenna_gain(:,3);
[X,Y,Z] = sph2cart(Az, El, Gn);
figure(1)
scatter3(X,Y,Z, '.')
grid on
The challenging part would be 3dB beamwidth, and interpolating it as a surface it you want to do that. Is ‘gain’ in dB now? What would you want to plot to look like (examples are helpful).
Before I tackle that, though, I suggest you see if one of the File Exchange contributions on antenna radiation pattern does what you want.
Youssef Khmou
Youssef Khmou 2014-9-5
编辑：Youssef Khmou 2014-9-5
Here is the proposed solution, i suggest that you use the polar coordinates as the following :
Data=load('data_ABS_antenna_CASMA.mat');
X=Data.ABS_antenna_gain;
[x,y,z]=pol2cart(X(:,1),X(:,2),X(:,3));
plot3(x,y,z,'.','MarkerSize',2)
grid on
xlabel('X');
ylabel('Y');
zlabel('Gain [dB]');
The corresponding figure is attached below :
As the vector z is in decibel, you can search for the indexes of z that are above max(z)-3dB :
[index,value]=find(z>=max(z)-3)
Next you plot the matrix with corresponding indexes :
figure; plot3(x(index),y(index),z(index),'.')
grid on
xlabel('X');
ylabel('Y');
zlabel('Gain 3dB');
The result is in the second figure :
The beam width is in the square of 20^2 units of surface, you can deduce the angular value .
  2 个评论
Aftab Ahmed Khan
Aftab Ahmed Khan 2014-9-5
Hi Youssef, Thank you for the detailed reply. What do you mean by saying, that beam width is the square of 20^2 units of surface ? Can you explain to me ? Thanks once again.
Youssef Khmou
Youssef Khmou 2014-9-5
in terms of Cartesian coordinates i mean. The final result is part of the ellipsoid , using the x,y, and z values you can calculate the theta beam width .

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Antennas, Microphones, and Sonar Transducers 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by