US1513223A - Receiving circuit for the elimination - Google Patents

Description

Oct. 28, 192 4. v I 1,513,223

j F. CONRAD RECEIVING CIRCUIT FOR THE ELIMINATION OF STATIC DISTURBANCBS 'F11ed, .0ct. 17, 1918 INVENTOR WITNESSES:

TTORNEY Patented Oct. 28, 1924.

UNITED STATES PATENT OFFICE.

FRANK CONRAD, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR- T WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

RECEIVING CIRCUIT FOR THE ELIMINATION 01* STATIC DISTURBANGES.

Application filed October 17, 1918. Serial No. 258,530.

ple and effective means whereby interfer-.

ence, particularly that known as static, may be largely eliminated, at the same time permitting the readyreceipt of transmitted impulses.

The single figure of the accompanying drawing is a diagram of a wireless receiving circuit embodying a preferred form of my invention.

In the wireless transmission of intelligence, it is well known that the receipt of transmitted impulses is frequently seriously disturbed by static charges produced upon the antenna by the passage of wind thereoyer. these static charges flowing to ground through the receiving apparatus. Qimilarly. the passage of elec-trostatically char ed clouds over the antenna attracts or repels chargesfrom the ground, these also passing through the receiving apparatus and confusing the operator.

I find that the static charges and static induction in antennae of different heights is substantially the same, whereas the intensity of the impulse set up in an antennaby incoming signals varies with the height. being much stronger for an. antenna of considerable height than for one of moderate height. I make use of this phenomenon in eliminating the disturbing effects of static electricity by employing two antennae for the receipt of messages. these antennae being so associated with receiving apparatus that the substantially equal charges imparted thereto by static influences cancel each other within the receiving apparatus. thus being rendered imperceptible to the operator. The unequal amounts of energy imparted to the antenna by incoming impulses fail to cancel each other and thus a residual eifect is imparted in the receiving apparatus which may be amplified if desirable in order to render it more clearly perceptible to the operator.

Referring to the drawing for a more detailed understanding of my invention, I show a relatively l'iigh wireless antenna at l and a relatively low antenna at 2. These antennas are shown of the flat-top type but it is to be understood that any antennae of the open-circuit kind may be used. Some antennae, usually in the form of a coil, act wholly, or at least largely, by the change in flux through them which is caused by an arriving ether wave. Other antennae act wholly or mainly in virtue of the electrostatic changes which accompany such a wave. I have used the term open-circuit antenna herein to designate any form of antenna belonging in the latter class. A receiving transformer is shown at 3 and the antenna 1 is connected to one end of a primary widing 4 thereof. whereas the antenna 2 is connected to the other end thereof. An

adjustable tap 5 is provided at an intermediate point in the primary winding 4 and is grounded at 6. The secondary winding 7 of the transformer 3 is connected, to a recei ing circuit of usual form.

Assuming equal sizes for the two antennae. the amounts of energy received therein are substantially equal with undesired static disturbances but are quite unequal with trans mitted impulses, the high antenna developing much more energy in the latter case. The point of attachment 5 is, under these conditions, placed at substantially the mid point of the winding 42, so that, with a given static impulse, the upwardly flowing current in the lower half of the winding 4 magnetically neutralizes the downwardly flowing; current in the upper half of this winding. the current of both antennae flowing to ground though the tap 5 and the lead 6. As a result, with a static impulse, no flux is de veloped in the transformer 3, and consequently, no electromotive force is produced in the winding 7 and no effect is produced in the local receiving circuit.

Turning now to the effect upon the receipt of a transmitted impulse, the current flowing from the antenna 1 is much larger than that flowing from the antenna 2 and, therefore, the magnetomotiye force developed in the lower half of the winding 4 is greater than that developed in the upper half thereof. As a consequence, flux is developed in the core of the transformer 3 which traverse the secondary winding 7 setting up curren flow in the local receiving circuit. The arrivingsignal produces a greater effect on the antenna 1, not only because a higher antenna possesses a' better receiving" capacity, but also because, being farther from roofs, trees and the like, it is more exposed to the action of the arriving wave.

It is obvious that the resultant impulse at the receiving instrument is considerably weaker than would be the case were this apparatus connected to a single antenna, but any well-known type of amplifier may be employed to increase the magnitude of the signals so that they shall be readily audible.

While I have shown my invention in its preferred form, it will be obvious to those skilled in the art that it is susceptible of still other minor changes and modifications.

without departing from the spirit thereof and desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims. I claim as my invention: A

1. In a wireless receiving circuit, the com bination with two antennae of different heights, of a common local receiving circuit differentially connected to said two antennae and susceptible of adjustment so that the energy received on one antenna from a static impulse cancels the energy received upon the other antenna, and so that similar cancellation is not effected with incoming transmitted impulses.

2. In a Wireless receiving circuit, the combination with two antennae of different heights, of a common receiving transformer having its primary winding connected tween said antennae, a local. receiving circuit dynamically interlinked therewith, and an adjustable connection from an intermediate point in said transformer primary winding to ground.

4. Inradio signaling apparatus, an antenna system having associatedportions an ranged at different elevations butat tially the same distance from the source of signals to be received, and means for detecting signals including means for balancing out the effects of static disturbances.

5. In a signal receiving system, two adjacent flat-top antennae of different height.

. 6. In a signal receiving system, two adja-. cent flat-top antennae of different height and signal translating means controlled by the difference of energy between said antennae.

In testimony whereof, I have hereunto subscribed my name this 25th day of Sept. 1918. i

FRANK CONRAD-

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