There are a bunch of terms thrown around when looking into building an EFHW Antenna. This breaks it down for you. I hope it helps!
Term: Ground (Earth / Station Ground) What It Is: Physical connection to earth (ground rod, house electrical ground) Purpose in EFHW: Safety - Static drain, lightning path, RF reference Do You Need It?: Yes (at shack entry) Where It Goes: Coax shield bonded at house entry panel Notes for Your Setup: Required by electrical code. Provides return path via coax shield.
Term: Counterpoise What It Is: Short wire (or coax shield section) acting as “other half” of antenna Purpose in EFHW: Provides RF return path for the end-fed wire Do You Need It?: Optional (often not needed) Where It Goes: Clip to SO-239 shield or add ~0.05λ wire Notes for Your Setup: Your transformer has no lug - coax shield usually works. Add short wire only if needed.
Term: Lightning Arrestor (Surge Protector) What It Is: Device (gas tube or inductor type) on the coax Purpose in EFHW: Diverts high-voltage surges and static to ground Do You Need It?: Strongly recommended Where It Goes: At coax entry into house, bonded to ground Notes for Your Setup: Protects radio from strikes and static. Cheap insurance.
Term: Choke (Common-Mode Choke / Line Isolator) What It Is: Ferrite core with coax wound on it (or beads) Purpose in EFHW: Blocks unwanted RF on the outside of coax shield, which can cause noise, shocks, and damage to equipment Do You Need It?: Highly recommended Where It Goes: On coax near transformer or ~0.05λ down the line. (In antenna engineering, λ represents the wavelength of an electromagnetic signal) Notes for Your Setup: Prevents RF in shack, noise, and SWR issues. Most useful addition.
Term: Transformer (Unun, usually 49:1) What It Is: Impedance matching box (high-Z antenna to 50Ω coax) Purpose in EFHW: Matches the high impedance of end-fed half-wave to your radio Do You Need It?: Yes, it is absolutely necessary. Where It Goes: It is part of the antenna, the antenna wire will attach to it. Notes for Your Setup: Converts ~2500Ω to ~50Ω.