The end fed half wave antenna is an antenna with a slightly higher gain compared to a half wave dipole. At the end of a half wave radiator the impedance is very high. By using a quarter wave stub the feedline impedance can be matched to the radiator. A 50 ohm impedance can be found approximately at λ/40 from the shortened end of the stub. Usually tuning is required. The impedance of the stub feedline is not critical but it should be of a low loss type, preferably an open air isolated line.
Velocity factors of various stub insulation materials
| Air | 1.0 | |
| Polyethylene (PE) | 0.659 | RG6,RG8,RG58,RG59,RG174,RG213,RG214 |
| Foam polyethylene (FE) | 0.79-0.88 | |
| Air spaced polythene (ASP) | 0.84-0.88 | |
| Polystyrene (PS) | 0.626 | |
| Foam polystyrene (FS) | 0.910 | |
| Solid PTFE | 0.695 | RG142,RG400,RG393 |
| Air spaced PTFE (AST) | 0.85-0.90 | |
| PMMA (Acrylic, Plexiglass) | 0.60 | |
| Nylon | 0.47-0.53 | |
| Vinyl (PVC) | 0.35-0.58 | |
| Glass | 0.35-0.51 | |
| Snow | 0.91 | |
| Ice | 0.56 | |
| Water | 0.11 |