HamWaves RF Calculators

HamWaves groups RF transmission-line, coil, matching and antenna calculators, including external resources. Its Qoil tool models a single-layer helical round-wire air-core coil from centre-to-centre mean diameter and coil length, conductor diameter, turns, material properties and frequency. Geometry uses mm and design frequency MHz; outputs include effective inductance in µH, reactance/resistance in Ω, unloaded Q and self-resonant frequency. The guide distinguishes the effective circuit at one design frequency from a lumped equivalent valid over a limited nearby band. It documents skin/proximity and end corrections, while noting an approximate effective-diameter model can overstate inductance. A negative reported inductance above first self-resonance represents capacitive behavior within the model. Keep geometry and frequency with comparisons.