As an example, Hallén wrote his famous integral equation to give an exact treatment of antenna current wave reflection at the end of a tube-shaped cylindrical antenna in 1956, but his first work on this subject [2] probably goes back to 1938. This equation enabled him to show that on a thin wire the current distribution is approximately sinusoidal and propagates with nearly the speed of light. For this treatment that is an important contribution. We will learn here that optimizing the effective length of a rod antenna will become directional and will have a radiation pattern that provides gain.