English: Animation showing how a Beverage antenna works. The Beverage antenna, invented by Harold H. Beverage in 1919, is a wire traveling wave antenna used for receiving in the medium wave and long wave bands. It consists of a horizontal wire several wavelengths long suspended above the ground, grounded at one end with a resistance (R, right) equal to its characteristic impedance, and at the other end attached to the transmission line to the receiver. It receives vertically polarized radio waves, but unlike other antennas is mounted near the ground. Due to the imperfect conductivity of the ground, near the ground the electric field vector (E, red arrows) of low frequency ground waves is not vertical but has a component parallel to the ground. The antenna acts as a transmission line with the Earth as the other conductor. On a transmission line the velocity of waves is slower than the speed of light. When the radio wave is incoming at the correct angle θ, the speed of the radio wave matches the speed of waves on the antenna, so current (I) induced in the antenna by the horizontal component of the electric field (small horizontal red arrows) adds up. An alternating wave of current (I, blue line) travels down the wire, increasing in amplitude the farther it goes, until it reaches the end of the antenna (I_O, right) where it travels through the feedline to the receiver. Radio waves originating from the other direction (left) induce waves on the wire traveling to the right, which are absorbed by the terminating resistance R, so the antenna has s unidirectional radiation pattern, sensitive to signals from the right only.