US1927880A - Signaling - Google Patents

Description

Sept. 26, 1933. M Q -r r AL 1,927380 SIGNALING Filed Oct. 15, 1929 Patented Sept. 26, 1933 SIGNALING Maximiliaan Julius Otto Strutt and Popko Reinder Dijksterhuis, Eindhoven, Netherlands, assignors to Radio Corporation of America, a

corporation of Delaware Application October 15,

1929, Serial No. 399,718,

and in the Netherlands October 31, 1928 2 Claims.

' The invention relates to a method and means for transmitting wireless signals and more particularly wherein directional radiation and aerial systems are used.

Various experiments have proved that the strength of reception at a definite point depends on the directional effect of the transmitting aerial in a vertical plane. In one of these experiments use was made, for example, of a horizontal aerial with a reflector having the shape of a parabolic cylinder; and, it was found that with two different positions of the reflector the strength of reception at a definite station to which the rays were horizontally directed, was a maximum and that between these two positions of the reflector a low minimum value of the signal strength was located.

According to the invention, the insight obtained by the above mentioned experiments is made subservient to the solution of the problem of eliminating or at any rate reducing the known and dreaded fading eifect.

As known, the fading effect is a phenomenon which occurs irregularly at a receiving station and which probably depends on the path which the incident electromagnetic oscillations have followed in space. If the radiated oscillations reach the receiving station along two different paths, it is less probable that the reception from two directions is troubled by fading. It is possible therefore to ensure a reception which is not troubled by fading by arranging some distance apart from each other two aerials which are controlled by the same transmitting installation.

However, due to the electrical properties of the line which connects the two aerials with the transmitting installation, it is necessary to provide a device which allows of keeping in phase the radiation of these two aerials.

This inconvenience does not occur with the present invention according to which two or more aerial systems controlled by the same transmitting installation are arranged in the same place in such manner that their directions of radiation in a vertical plane are different.

The invention will be set forth more fully with reference to the accompanying drawing in which Figure 1 shows diagrammatically one mode of realization of the invention.

Figure 2 represents an aerial of suitable shape adapted for use in the mode of realization according to the invention.

Figure 1 shows two aerials 1 and 2 which are In order to prevent radiation in of the axis of the parabolic cylinder,'an aerial the direction is used whose directional effect is normal to the longitudinal direction of the said axis. be made, for example, of an aerial having a shape as represented in Figure 2 which shows an aerial with which'a directional effect normal to the longitudinal direction of the aerial is ensured owing to the fact that the radiation of the'suce cessive half -wave lengths are alternately utilized and suppressed. 3

For transmitting wireless cal point on the earth use may be made-of the two paths along the earth by transmitting in; opposite directions with the aid of 'two or more:

aerials which are each provided with a reflector.

Use may signals to diametri- The use of a reflector is not essential for the invention but is desirable for long distance transmission in which otherwise the radiation in opposite directions around the globe would cause a disturbing effect at the receiving station.

' We claim:

1 In a system for transmitting utilizing electromagnetic wave phenomena in space, the method of eliminating electromagnetic Wave fading phenomena at a receiver which includes simultaneously propagating in a highly directional fashion from a plurality of spaced points, in two fixed and predetermined directions in a single vertical plane, electromagnetic wave energy to a receiver. I I

2. A radio transmitting antenna system having, in combination, a horizontal dipole antenna, a parabolic reflector for said dipole arranged to directively propagate the energy radiated from said dipole upwardly in a directionforming a predetermined angle with the horizontal plane, a second dipole antenna spaced away from said first dipole, and a parabolic reflector for said second dipole antenna arranged to directively propagate the energy radiated from said second antenna upwardly in a direction forming a second predetermined angle with the horizontal plane, both said dipole antennae being arranged to directively and simultaneously propagate energy in the same vertical plane, but in different directions, the angles said directions form with the horizontal plane being chosen in such manner that for both directions reception is a maximum.

MAXIMILIAAN JULIUS o'r'ro STRU'IT. POPKO REINDER DIJKSTERHUIS.

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