desired type of instruments and arrangement of connecting circuits may be employed.
In Fig. 1a suitable sending instruments are 110conventionally shown. These comprise a generator 15, transformer 16, spark gap 17, condenser 18 and key 19.
The above-mentioned instruments are well known in the art of radio or magnetic wave 115signaling, and need not be further described.
20 is an antenna for radiating or receiving electromagnetic waves, and as shown in Fig. 1 extends horizontally or substantially parallel to the earth’s surface and buried in the 120earth. This antenna may be of any suitable or desired length, and is completely inclosed within a metallic covering, casing or screen 21 which may be a tube or pipe of lead, iron or any other suitable metal. The antenna is 125insulated from the metallic covering or casing by means of insulation 22. It will thus be seen that while the antenna is buried in the earth it is completely insulated therefrom and from the metallic covering or casing.130
The receiving instruments shown in Fig. 1 are associated with the antenna by means of an inductive coupling comprising windings 23 and 24 of a transformer, but may be 135associated therewith in any other suitable manner. The other terminal of winding 24 of the coupling is connected to ground at 25.
In the embodiment of the invention shown in Fig. 2 the ground connection is replaced 140by a second antenna 20′ extending in a direction different from the direction of antenna 20, the signal instruments being connected between the antennæ as indicated by the winding 24 of the inductive coupling. In 145this figure also is shown the arrangement by which the signal instruments are located in the chamber 26 below the surface of the earth.
Fig. 3 shows an arrangement similar to 150Fig. 1 but with the employment of a second antenna 20′ in place of the ground connection shown in Fig. 3.
Fig. 4 shows an arrangement similar to Fig. 3, but with the antennæ slightly 155elevated above the surface of the earth by means of struts or pins 28. Thus while the antennæ extend substantially parallel with the surface of the earth, the metallic covering or casing is not in direct contact with the 160earth but is separated therefrom by a short space. It may or may not be insulated from the earth according to the material of which the struts or pins 28 are made, that is whether they are of conducting or of 165non-conducting material.
Fig. 5 shows the employment of two antennæ submerged beneath the surface of the earth where there is water, the water being indicated at 29. Here the metallic covering 170or casing is in contact with the water, but the antennæ and their connecting circuits are insulated from the water.
Fig. 6 shows the employment of ground connections 30 for the outer ends of the antennæ.175
In order to reduce the static, as above indicated, the casing 21 is divided into sections 31, which sections may be of any desired length, preferably very short, such as sixteen feet for instance. This particular180 length is suggested for the reason that it is the length of ordingary iron pipe which may be used for the purpose. The sections 31 are connected to each other by insulating couplings 32, which may be made of rubber185 hose clamped to the metallic sections by clamps 33 or other suitable means.
Careful tests and experiments have shown that by the employment of sectional metallic casing in intimate contact with the earth190 but insulated from the radio conductor or antenna, the sections of the casing being insulated from each other and connected by couplings of insulating material, very much longer antennæ may be employed than is195 possible with the continuous metallic casing. Also, when comparing the use of antennæ of the same length, the static is much less with the sectional casing.
It will be understood that while I have200 shown and described arrangements embodying my invention in which one antenna and also two antennæ are employed, any desired number may be used, and it is desirable to have them extend in the proper direction205 to obtain the maximum effect both in sending and receiving of the electromagnetic waves. For this purpose a number of antennæ may be employed radiating in different directions from the instruments, and suitable switching210 mechanism may be provided for connecting any one or more of the antennæ to the signal instruments. Such an arrangement is shown and described in the pending application of myself jointly with Henry H. Lyon,215 S. No. 130,603, to which reference is here made for further details, so that it is unnecessary to describe such an arrangement in this application.
It has been stated that the invention is220 applicable to the surface of the earth where there is water, one such application being illustrated in Fig. 6. It will be understood also that the invention is also applicable to ships at sea, but as the employment of my225 new antenna arrangement in such connection is obvious it is though that illustration is unnecessary.
In accordance with the patent statutes I have described which I new believe to be the230 best embodiment of the invention, but I do not wish to be understood thereby as limiting myself or the scope of the invention, as many of the changes and modifications may be made without departing from the spirit of235