Beverage antenna

Herold beverage discovered in 20 that an otherwise nearly bidirectional long wire antenna becomes uni-directional by placing it close to the lossy earth and by terminating one end of the wire with a non-inductive resistor with a resistance approximately matched to the characteristics or surge impedance of the antenna. This was the fundamental discovery in his 1921 patent. From the transmission line theory we know that the line terminated with load impedance equal to characteristic impedance (Z๐), there is only a traveling wave present on the line. Since there is no reflected wave, there is no standing wave on the line. Then the line is said to be non resonant.

   

It consists of a wire one or two wavelength long. Note that the length of 1 or 2λ is not a small length at LF or MF; it is hundreds of feet at MF to several kilometers for LF. The wire runs parallel to the earth’s surface from the receiver towards the direction of the desired signal. The wire is suspended by insulated supports approximately two meters above the ground. A non-inductive resistor of value equal to characteristic impedance is installed from the far end of the wire to the ground. As the wire is properly terminated, the structure becomes a non resonant antenna.