Ham Radio For Dummies, 3rd Edition

Chapter 18

Technical Fundamentals

No matter what interests you in ham radio, from ragchewing to equipment design, you’ll get more out of the hobby if you have a basic understanding of a few technology details. If you want to dive in a little deeper, your license study guides will get you started. The ARRL Handbook and The ARRL Antenna Book have been reliable references for many years. Online you can use the ARRL Technical Information Service (www.arrl.org/technology) that is available to all hams. Appendix B of this book is a radio math supplement that provides some common math formulas you’ll encounter in ham radio.

Electrical Units and Symbols

You should know each of the basic electrical units and what they represent:

• Voltage (volts, V): The electrical potential between two points, represented as V, v, E, or e in equations.
• Current (amperes, A): The electrical charge flowing in a circuit, represented as I or i in equations.
• Power (watts, W): The rate at which energy is expended or dissipated, represented as P or p in equations.
• Resistance (ohms, Ω): Opposition to current flow, represented as R or r in equations. Ω is a capital Greek letter omega.
• Reactance (ohms, Ω): Opposition to AC current flow, represented as X in equations.
• Impedance (ohms, Ω): Combination of resistance and reactance, represented as Z in equations.
• Conductance (siemens, S): The inverse of resistance, represented as G or g in equations.
• Capacitance (farads, F): The ability to store energy as an electric ...