#ZachStar says the scariest thing in #EE is the #SmithChart. I am of a different view. Many E&M topics, including resonant cavities, waveguides, antennae, etc., are far more daunting than impedance matching transmission lines.
Sure, a paper Smith Chart is not so hot, but a Smith Chart slide rule is quite fun to use. And an HP network analyser with a built-in Smith Chart makes it all definitely non-scary.