| Difficulty | Prasad-Specific Tip | |------------|---------------------| | Near-field vs far-field derivations | Focus on terms with ( 1/r ) (far field); ignore ( 1/r^2 ) and ( 1/r^3 ) for radiation. | | Mutual impedance in arrays | Use the induced EMF method (Chapter on Arrays). | | Ionospheric refraction | Understand virtual height vs true height; Prasad uses secant law extensively. | | Complex feed networks (Yagi) | Treat as parasitic coupling; no direct feed to reflectors/directors. |