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Specifically I'm unsure about a factor of 2 scale factor when converting the measured insertion loss to a double sided spectrum, necessary for the ifft.

In the past I have always believed that converting e.g. a double sided spectrum from an fft into a single sided one requires multiplication of the magnitude by a factor of 2 and intuition suggests that converting a single sided spectrum into a double sided one should require dividing by a factor of 2. However this logic doesn't seem to hold when converting for example an insertion loss measurement (typically a single sided spectrum) into an impulse response through an ifft.

Can anyone confirm whether you should/ shouldn't scale your measured insertion loss by a factor of 2 when converting to a double sided spectrum?

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I think you're asking about the spectrum of the Analytic Signal.

Yes, the "energy" of the negative frequencies were transferred to the positive frequencies and the positive frequency components are doubled in magnitude.

And when converting the analytic signal back to a real signal, you take the real part and ditch the imaginary part. That's the one-half.

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  • $\begingroup$ Not quite, it's more a question of how to convert what is measured on real world equipment (e.g. a VNA) to the equivalent double sided spectrum. Essentially, is what's measured the single sided spectrum, or is it more like half of a double sided spectrum? With the single and double sided spectra being related typically by a factor of 2. $\endgroup$ Commented Oct 30 at 13:58
  • $\begingroup$ Well, SSB comes directly from the Analytic signal. This might be more relevant than you think. $\endgroup$ Commented Oct 30 at 14:00
  • $\begingroup$ OK I will look into it more, thanks. $\endgroup$ Commented Oct 30 at 15:55

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