Frequency response of passive return-to-zero downconversion mixer

[promach]

Why for fourier analysis/representation of square wave, the book snippet shows first harmonics to have amplitude of 2/pi  ?

https://en.wikipedia.org/wiki/Square_wave#Fourier_analysis

In the frequency domain, this harmonic consists of two impulses at ±ω_Lo , each having an area of 1/pi. Thus, as shown in Fig. 6.18(b), the convolution of an RF signal with these impulses creates the IF signal with a gain of 1/pi ( ≈ -10 dB).

Could anyone elaborate on the above book sentence quote ?

[T3sl4co1l]

Amplitudes are peak, not RMS.  Not that that matters regarding the factor of pi, for which that's simply the amount needed to reconstruct a square wave.

Tim