Beverage antenna

A Beverage antenna consists of a horizontal wire from one-half to several wavelengths long (tens to hundreds of meters; yards at HF to several kilometres; miles for longwave) suspended above the ground, with the feedline to the receiver attached to one end, and the other end of the wire terminated through a resistor to ground.

The advantages of the Beverage are excellent directivity, a wider bandwidth than resonant antennas, and a strong ability to receive distant and overseas transmitters.

Its disadvantages are its physical size, requiring considerable land area, and inability to rotate to change the direction of reception.

[4][5] He discovered in 1920 that an otherwise nearly bidirectional long-wire antenna becomes unidirectional by placing it close to the lossy earth and by terminating one end of the wire with a resistor.

The Beverage antenna consists of a horizontal wire one-half to several wavelengths long, suspended close to the ground, usually 3 to 6 m (10 to 20 feet) high, pointed in the direction of the signal source.

[3][2] At the end toward the signal source it is terminated by a resistor to ground approximately equal in value to the characteristic impedance of the antenna considered as a transmission line, usually 400 to 800 ohms.

A single-wire Beverage antenna is typically a single straight copper wire, between one-half and two wavelengths long, run parallel to the Earth's surface in the direction of the desired signal.

The antenna can also be implemented as an array of 2 to 128 or more elements in broadside, endfire, and staggered configurations, offering significantly improved directivity otherwise very difficult to attain at these frequencies.

Very large phased Beverage arrays of 64 elements or more have been implemented for receiving antennas for over-the-horizon radar systems.

The AT&T receiving Beverage antenna (left) and radio receiver (right) at Houlton, Maine , used for transatlantic telephone calls, from a 1920s magazine
Animation showing how the antenna works. Due to ground resistance the electric field of the radio wave ( E, big red arrows ) is at an angle θ to the vertical, creating a horizontal component parallel to the antenna wire ( small red arrows ) . The horizontal electric field creates a traveling wave of oscillating current ( I, blue line ) and voltage along the wire, which increases in amplitude with distance from the end. When it reaches the driven end (left) , the current passes through the transmission line to the receiver. Radio waves in the other direction, toward the terminated end, create traveling waves which are absorbed by the terminating resistor R , so the antenna has a unidirectional pattern.
A Beverage antenna that can be improvised for military field communications, from a 1995 U.S. Army field manual. Rather than being grounded, the resistor is attached to a second lower wire which serves as a counterpoise , an artificial ground for the transmitter. The antenna's main lobe , its direction of greatest sensitivity, is to the right, off the end of the wire that is terminated in the resistor.