US1182003A - Signaling by electromagnetic waves. - Google Patents

Description

R. A. FESSENDEN.

SIGNALING BY ELECTROMAGNETIC WAVES.

APPLICATION FILED APR. 19. 1906.

1 182,003 Patented May 9, 1916.

W W 1w 'EEMMM UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, 0F BRANT ROCK, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO SAMUEL M. KINTNER, OF PITTSBURGH, PENNSYLVANIA, AND HALSEY M. BARRETT, OF BLOOMFIELD, NEW JERSEY, RECEIVERS.

SIGNALING BY ELECTROMAGNETIC WAVES.

Application filed April 19, 1906.

T 0 all whom it may concern Be it known that I, REGINALD A. FEssEN- DEN, a citizen of the United States, residing at Brant Rock, in the State of Massachusetts, have inventei a certain and useful Improvement in the Art. of Signaling by Electromagnetic Waves, of which the following is a specification.

My invention relates to the sending of electrical signals and more particularly the generation of electro-magnetic waves for wireless telegraphy.

The primary object of the invention is the more eflicient, certain and controllable production of oscillations, as hereinafter more fully described and claimed.

In the accompanying drawings forming a part of this specification Figures 1, 2 and 3 illustrate forms of apparatus for carrying out my invention.

The use of a spark for signaling by electromagnetic waves is very objectionable not only by reason of its inefficiency and consid erable waste of energy, but also on account of the noise produced and its inconstancy in operation, the intensity of the signal? varying from spark to spark. It is also objectionable in that as generally used it gives few impulses of short duration. By my method these objections are overcome, and the waves are produced efliciently without a spark gap.

In Fig. 1 is shown an induction coil having a core 1, a secondary coil 2, a primary coil 3, a break 4, and a condenser 5 shunted across the break. cited by any suitable means as for example by the storage batteries 6. The secondary coil 2 may have one terminal connected to the aerial and the other grounded as shown.

In the practice of my invention the inductance of the circuit containing the primary coils is made so as to be large compared with its ohmic resistance when the break 4 is closed. As the storage batteries 6 may have high resistance they may be shunted by the condenser 7 The time which a current takes to rise in R where L is the coeflicient of self induction, and R the resistance.

The natural frequency of an electric osa circuit depends upon the time constant Specification of Letters Patent.

The induction coil is ex Patented May 9, 1916.

Serial No. 312,724.

cillation depends upon the factor of /LC where L is the coefficient of self induction and C the capacity.

I so proportion the self induction of the pr mary 3, the ohmic resistance R of the circult when the break 4 is closed, and the capacity of the condenser 5, that the current in 3 rises to the desired value during the time of closure of the break 4, and so that on the opening of the break, the natural period of the inductance 3 and capacity 5 is such as to generate oscillating currents of the desired frequency in the antennae, and thereby radiate electromagnetic waves. It is preferred to have the frequency of the circuit 3, 5, 6 equal to the natural frequency of the antennae circuit consisting of the antennae, the secondary 2 and ground, and this 18 preferably done by adjusting the condensers 8, 5 and 7, all of which are perferably variable.

In order to make a sharp break it is preferred to inclose the break 4 in compressed air as shown, as I have found that by this means the break is made much more sharp and a much higher voltage can be produced.

In Fig. 2, is shown another form in which 9 is an inductance, 10 a rotating commutator revolving in compressed air, 11 a brush bearing on the commutator, 12 and 13 condens-' 15 is an air cuit 9, 13, 10 is preferably made such that pacity 12 or the capacity 5 is short circuit-' ed, and that when the circuit controllers are open the capacity 12is in series with the inductance 9 and the capacity 5 is in series with the inductance 3.

Antennae 16 16 alternately may be connecteither directly as through the inductance 9 and grounded, or inductively through the. secondary 17 and grounded as shown. With an ordinary induction coil it is found that the frequency of the oscillations of the pri mary circuit will not, as a rule exceed 10,000 per second.

For the efficient generation of electromagnetic waves it is found in practice that theheight of the antennae should not be less than 5 of the wave length and hence with an ordinary type of induction coil the antenna: would have to be approximately 3,000 ft. high for the most efiicient operation. In the practice of my invention, however, I so proportion the inductance of the primary and the capacity across the break that frequencies as high as 100,000 may be obtained in which case antennae 300 ft. more or less high give very efficient radiation. I also, prefer to adjust the capacities and inductance in the primary or antennae circuits so that the antennae circuit is resonant with the primary circuit, thereby obtaining ,an increase in efficiency. I also prefer to have as many breaks per second as possible.

I claim herein as my invention:

1. In apparatus for generating high frequency oscillations, the combination of an inductance, a circuit controller, a source of current, and a capacity, said capacity being connected so as to be short circuited when 1 the circuit controller is closed, and in series. with the inductance when the controller is and a capacity in shunt to the current source.

3. Apparatus for generating high frequency electrical oscillations directly from a current source comprising a closed oscillating circuit including an inductance, two

condensers, a current source shunting one.

of said condensers and a circuit controller,

intermittently shunting the other condenser, substantially as described.

4. Apparatus for generating high frequency electrical oscillations comprising an antenna-to-ground circuit containing a capacity and inductance, a local closed circuit including said inductance and capacity and also a current source shunted by another capacity, combined with a circuit controller operating to alternately connect the capacity in the antenna in series and in shunt in the antenna at high frequency.

In testimony whereof, I have hereunto set my hand.

REGINALD A. FESSENDEN.

Witnesses:

ROBT. S. KEARNEY, DARWIN S. WOLCO'IT.

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