MATLAB: Plot attenuation against wavelength

attenuationplotwavelength

How to Plot attenuation against wavelength?

Best Answer

Hi Hadeel,

Here is an example of Signal Attenuation Due to Rainfall:

c = physconst('lightspeed');
rr = 20.0; 
freq = [1:1000]*1e9;
L = rainpl(10000,freq,rr);
wavelength = c./freq;  % wavelength calculated by speed of light/frequency
semilogx(wavelength,L)
grid
xlabel('Wavelength (m)')
ylabel('Attenuation (dB)')

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MATLAB: How to plot array beampattern with Frost beamformer weights

You can consider translating the weights to frequency domain to obtain the appropriate frequency response. Then you can compute the pattern at the given frequency.

    % plot pattern
    % consider 16 bands and pick the band corresponding to 2 kHz
    M = 16;
    wfreq = fft(reshape(yweights,16,[]).',M);
    freqvec = [0:7 -8:-1]*fs/M;
    bandidx = 5;  % corresponding to 2kHz
    freqbin = 2e3;
    hstv = phased.SteeringVector('SensorArray',h,'PropagationSpeed',c);
    sv = step(hstv,freqbin,incidentAngle);
    figure
    pattern(h,freqbin,-180:180,0,'PropagationSpeed',c,'Weights',sv.*wfreq(bandidx,:).',...
        'CoordinateSystem','polar','Type','powerdb');

HTH

MATLAB: The attenuation due to rainfall calculated by function “rainpl” is different from ITU-R.838

The plot you see is in dB scale, that's why it does not look like a linear model, but it is indeed linear.

I'm not familiar with the ITU software but as the documentation indicates, the function is based on ITU-R P.838-3, so it could be different to the original P.838 if that's what the software is based on. I did try compute values mentioned in P.838-3 using the function and was able to get the matching result.

HTH

Best Answer

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MATLAB: How to plot array beampattern with Frost beamformer weights

MATLAB: The attenuation due to rainfall calculated by function “rainpl” is different from ITU-R.838

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