A spectrum of a 2.4 GHz WiFi

Just for fun, below is a picture for a 2.4 GHz WiFi spectrum captured by a GWInstek-730 spectrum analyzer at my house

The bar lines don't represent WiFi channels, the channels are much wider - at least 20 MHz, these bar lines is just a feature of the sweep-tuned spectrum analyzer capturing fast changing signal. I believe that GWInstek-730 is an analogue sweep-tuned analyzer that does not perform DFT / FFT of a signal.

On Telegrapher's equations

I was always suspicious on telegrapher's equation derivation based on a circuit model

it was not convincing for me the way this model was derived, recently I stumbled across a derivation through Maxwell's equations http://cc.ee.ntu.edu.tw/~rbwu/course/EM2/Lec1_Telegrapher_Eq.pdf  , the two most important excerpts from the paper