An aerial of the size and type just described will send and receive the following distances.
These distances are only approximate and will vary with the efficiency of the operator and the location of the station.
When any of the transformers described later are used, the aerial should be 80 to 100 feet high. In this case the last named receiving outfit will have a range of from 500 to 1,000 miles.
Ground Connections.—The importance of a good earth or ground connection can hardly be overestimated. Whenever possible commercial stations are located on moist ground or near a body of water so that a good ground may be secured by imbedding zinc or copper plates in the earth or water. A ground on shipboard is easily secured by fastening a conductor to one of the ship's plates.
If the ground connection is poor, the natural period of the oscillation circuit is made irregular and short, so that the currents are choked in passing in and out of the earth. The result is an undesirable rise of potential at the lower end of the aerial and often harmful sparking at the ground connection. The transmitting and receiving ranges of a station are very considerably reduced through a poor earth.
Ground connection can often be obtained in the country by immersing metal plates in a well or a cistern. Where connection is made to a water supply pipe some sort of a ground clamp should be used to insure a good contact.
Fig. 23. Ground Clamp.
An efficient earth for portable outfits may be quickly formed by spreading a large area of wire netting over the ground.