Chapter 1: Electrical Foundations #

Welcome back to electrical principles! You already know voltage, current, and resistance from your Technician studies. Now we’re going to expand that foundation with the AC circuit concepts that make HF radio work.

We will learn about reactance, the opposition to AC that changes with frequency. Reactance and resistance combine to form impedance, which helps determine how your antenna system behaves. From antenna tuners to crystal filters, you’ll see resonance at work. Transformers let us match different impedances. We’ll also cover power measurements that help you understand PEP, and the decibel system that hams use to describe signal strength and power ratios.

These aren’t just abstract concepts. Understanding series and parallel circuits helps you design or even just understand antenna matching networks. Learning about reactance will help you understand why your antenna’s SWR changes with frequency. Knowing about transformers reveals how baluns work.

We’ll explain terms like “inductive reactance” and “impedance transformation” step by step, using practical radio examples throughout.