How to Use Duality Property for Finding Fourier Transform of sin x / x?

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SUMMARY

The Fourier transform of the function sin(x)/x can be evaluated using the duality property of Fourier transforms. The integral f* = Integral(sin(x)/x * exp(i*w*x) dx from -infinity to +infinity requires an understanding of the relationship between the sinc function and square waves. Specifically, the Fourier transform of a square wave with duty cycle d is given by d*sinc(w) = d*sin(pi*w*d) / (n*pi*w*d). Jordan's Lemma is not applicable in this context, making the duality property essential for solving the integral.

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  • Understanding of Fourier transforms and their properties
  • Familiarity with the sinc function and its applications
  • Knowledge of Jordan's Lemma and its limitations
  • Basic concepts of square waves and duty cycles
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Hi, how do I find the Fourier transform of this function sin x / x, i.e.,

f* = Integral( sin x / x * exp( i*w*x) dx from -infinity to +infinity ).

I've been using Jordan's Lemma up to this point, but it doesn't seem to
apply here as a way to evaluate the integral.

Thanks for any help.
 
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Hint: Use the duality property of Fourier transforms. Remember that d*sinc(w) = d*sin(pi*w*d) / (n*pi*w*d) is the Fourier transform of a square wave in the time domain with duty cycle d.

Edit: Fixed some things. If the time domain part confuses you, ignore it; I learned this stuff primarily from a signals & systems perspective.
 
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