and the antenna at 16. This latter extends in a direction substantially horizontal, either upon or below the surface of the 105earth, and is preferably in contact with the earth substantially throughout its length. The antenna thus constitutes a ground connection along its entire length, and, it is believed, a considerable portion of the earth’s surface about the antenna thus coöperates 110with the latter in sending or receiving oscillations.
Instead of being below the surface, as shown in Fig. 1 at 16, the antenna may lie upon the surface of the earth, as shown at 11516′, in Fig. 1a, being in intimate contact with the earth substantially throughout its entire length.
In coöperation with the antenna we may, and preferably do employ another earth 120connection, this being shown in Fig. 1 as a ground plate 17.
Fig. 2 is an embodiment of the invention in which two antennæ are employed extending in opposite directions, the second 125antenna 18 being connected in place of the ground plate shown in Fig. 1. This arrangement is more effective than with the use of the ground plate.
Fig. 2a shows the antennæ 16′ and 18′ 130extending in opposite directions upon the surface of the earth and in intimate contact therewith substantially throughout their length, the signal instruments connected between the antennæ being indicated by one 135member of the indirect coupling.
Fig. 3 shows the same arrangement as Fig. 2 but with sending instruments instead of receiving instruments. These comprise a generator 19, key 20, transformer 21, spark 140gap 22 and condenser 23. Any other sending arrangement and instruments may be employed instead of those shown.
In order to obtain the maximum efficiency it is desirable to have the antennæ disposed 145in a line at the right angles to the wave fronts, and in order that this may be accomplished for the different directions we provide antennæ extending in different directions but substantially horizontal or parallel to the 150surface and in contact with the earth throughout their lengths. Such an arrangement is illustrated in Fig. 4 where eight antennæ are shown. These are designated 16, 15524, 25, 26, 18, 27, 28 and 29. The instruments are shown connected to antennæ 16 and 18, but may be connected to any other two or more. Sometimes it is necessary to connect to several antennæ in order to 160obtain the best results. The signal instruments may be connected by any suitable switching devices to any two or more antennæ and the direction of transmission this ascertained. Usually the connection would 165be made with the pairs of oppositely extending antennæ, the but instruments may be connected to any two or more desired. Also, for multiplex transmission separate instruments may be connected to different pairs or groups.170
Any preferred switching devices may be employed to connect the instruments to the antennæ, a convenient arrangement being shown in Fig. 5. The instruments are connected to bus wires 30 and 31, and each 175antenna 16, 18, 25, 28 is connected to a switch blade 32, 33,34 and 35 respectively. Any additional number of antennæ desired may be employed in the same way. Each switch blade coöperates with a contact upon each180 bus wire. The instruments may thus be connected with any one or two or more antennæ.
The invention is also applicable to the surface of the earth where there is water. For instance, on the sea coast the antennæ185 may be run out from shore into the water or along the shore on the surface of or under the sand. In this way the system is useful for life-saving stations, light-houses, &c.
The system is also adapted to the use of190 vessels at sea, including submarines. We have demonstrated that the receiving is highly efficient when the antennæ are lying on the bottom, as shown in Fig. 9, either in fresh or salt water. The antennæ may also195 be supported by floats along the surface of the water, as shown at 184 in Fig. 8, or suspended in the water above the bottom.
A specific embodiment of this last mentioned feature of the invention is shown in200 Fig. 6 where 36 indicates a boat or vessel, 162 one antenna and 182 another antenna. The antenna 162 may be mounted along the side of the vessel but preferably insulated therefrom or attached only at the bow and205 trail toward the stern, or with vessels of word or other insulating material it may even be mounted inside. When the vessel is iron or other metal, the vessel itself may be employed as this antenna, provided the210 capacity is not too great.
By this arrangement it will be seen that very long antennæ may be used. The length of the antenna mounted upon the body of the vessel is only limited by the length of215 the vessel, and as many vessels are over three hundred feet long, and some are 600 to 800 feet, the necessary length of antenna for long distance work is readily accommodated. The other antenna, trailing for the stern220 of the vessel, may be at least as long as, or even longer than, the antenna mounted upon the body of the vessel. If desirable, these and the other antennæ described may be replaced by multiple strands.225
The antenna 182 may be a wire allowed to trail astern and will approximate the horizontal, according to the speed. Fins 183 may be added at intervals along the wire as shown in Figs. 7 and 7a, to increase this230