US1295245A - Method of and apparatus for radiosignaling. - Google Patents

Description

"R. A. WEA GANT at H. SHOEMAKER.

METHQD OF AND APP'ARATUS mgnwmsgemuus.

APPucmmi FILED JAN. 6.191s.

Patented Feb. 25, 1919;

INVEN O ATTORNEY as sra'rns rarnnr caries.

BOY A. WEAGANT, OF RQSELLE, AND HARRY SHOE MAKER, OF JERSEY CITY NEW JERSEY, ASSIGNORS T0 MARGONI WIRELESS TELEGRAPH COMPANY OF, AMERICA, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

METHOD OF AIETD APPARATUS FOR RADIOSIGNALING.

- Specification of Letters Patent.

Patented Febr25, 1919.

Application filed January 6, 1915. I Serial No. 70,570.

To all whom it mciy concern:

Be it known that we, ROY A. WnAeAN'r and HARRY SHOEMeKER, citizens .of the United States, residing, respectively, in the town of Roselle, county of Union, State'of New Jersey, and in the city of Jersey City, county of Hudson, State of'NeW Jersey, have jointly made certain new and useful Improvements in Methods of and Apparatus for Radiosignaling, of which the following is a specification.

This invention relates to apparatus for radio signaling and' consists of a receiving the ordinary tuning methods, can be so adjusted as to respond to a. maximum degree to electromagnetic waves having a definite period or frequency, audit is also commonly observed that such an aerial system \Ylll oscillate at its own period when excited by electromagnetic Waves having a widely different period; this is exceptionally true when such different magnetic Waves are quite strong or emanate from a nearby, powerful transmitter. The purpose of this invention is to construct an antenna system which is less responsive to disturbing impulses of a frequency differing from those used. for signaling purposes in said antenna system.

The usual arrangement of elevated wire I is employed; but included, there are fixed inreaction, and whether they be spaced at regular or irregular intervals, their inclusion in the antenna serves to concentrate in them to v the inductance of the antenna to a consideralble extent. Therefore, the inductance of the antenna is not uniformly distributed throughout its length as is the case with the ordinary antenna,up to the point where the tuning devices are insertedfbut is, on the other hand, unumformly distributed; These coils are placed in series in the antenna,

one after the other at'suita-ble intervals, andeach coil is provided with a shunt branch in which is included a condenser, preferably .a fixed condenser. This antenna is associated witha receiving circuit havingvwell known adjustable means for tuning and it results from the construction ofthe antenna that, when receiving electromagnetic Waves of predetermined frequency, waves of higher frequency or shorter Wave lengths are effectively excluded, and this is true whether the higher frequency oscillations are due to some interfering transmitter or to natural causes commonly known as static interference. The accompanying drawings illustratethe invention. Figure 1 shows theimproved receiving antenna; Fig. 2 is a modification; Fig. 3 shows a coiiperating transmitting antenna and circuits at a distant.

point or station. In each figure of the drawing there is an antenna In Fig. 1 there are a series of inductance coils 2', these may be closely wound coils of insulated wire and, as shown, coil 5 has the maximum inductance of any of the series of coils Coil 5 has somewhat less inductance and coil 7 has the least. There is also the usualinduc'torium havingi a coil 10 in the antenna a cooperating with 'coil 11 in the closed oscillating circuit; coil 11 is bridged ,by an adjustable condenser 12; there is a detector 14, a telephone receiver 15 bridged by a fixed coi-idenser 1!). The details of the receiving arrangement 11 to 16 constitute no'pa'rt of my present invention; any suitable arrangement may be used. The detector 14 is merely a diagrammatic symbol indicating any detector, for damped or undamped os- .ment 30; the generator is a high frequency alternatinggeneratcr included in circuit 32 which also includes a Morse transmitting key 33; there is a primary coil of an inducgap 38 and the primary coil of a t .rans former 39 having an adjustable secondary.

coil40 in the antenna, a.

torium 34; this inductorium or converter ha's 'aiscwndary coil.35 and core 36 of magnetic wire; coil is in the closed oscillationcircuit With-a condenser 37, a quenched spark The particular construction of the transmitter forms no part of my invention and any transmitter of damped or undamped oscillations may be used,provided, of course, that the damping is not excessive, this being a matter well understood in the art. In the antenna a shown in Figs. 1 and 2 each inductance coil z' is provided with a shunt circuit including a condenser 51. For convenience this may be called a local circuit. Each local circuit, consisting of condenser and'in- 'ductance, is adjusted to have a natural time period which is diii'erent from that of any of the incoming electromagnetic Waves with which the aerial is intendedto be used; such an [arrangement of inductance and capacity inparallel with it connected in series in another electrical circuit namely, the antenna, in this case, has a very high impedance to electrical oscillations whose time period is that to which this inductance and capacity have been adjusted. In fact, if the resistance of this inductance and capacity is zero this impedance croppcsition to the flow of current in the main circuit Will be infinite; in actual practice if the resistances are small this impedance will be very large. By having a large number of these coils in a single antenna system means are provided which definitely prevent the passage of electrical oscillations having the period of any of these'local circuits. .It :Will be seen that by properly adjusting the constants of these inserted devices a Wide range of wave lengths can be excluded from the system; for instance, if one combination had a natural period of 600 meters it would effectively exclude-wave lengths between, say, 575 meters and 625 meters; the next local circuit would have a period of, say, 700 meters, which would. effectively exclude any wave lengths between, say, 67 5 and 725 meters, and so on. Preferably the longest natural period of any of these arrangements in a given aerial system is short in comparison to the wave lengths which it is desired to receive; "for instance, to receive a wave of 12,000 meters it is undesirable to use any insented'local circuit having'a natural period greater than 5,000 meters.

.Durjiig' 'regular normal operation of the transmitter oscillations of predetermined frequency are apparent in the antenna a of the receiving stations Figs. 2 and It will be-noted that our improved apparatus provides not only a means for opposing inductive reactions to undesired frequencies by means of inductances, as disclosed in the application of Roy A. W eagant, Serial Number 70,571, referred to above, but that this action is rendered more ellicient by the introduction of concentrated inductances of different values at points along the length of the antenna, and that in addition thereto a series of resonant circuits of different constants are arranged throughout the length of the antenna, so that efi'ective opposition to frequencies of certain predetermined values is presented. It results from the arrangement of our invention that if undeference from oscillations of undesired fro quencles, irrespective of their origin, 2'. e., whether emanating from neighboring stations, static disturbances, or the station where the antenna is located, and that our invention is applicable to radio telephony as well as to radio telegraphy.

What We claim is:'

1. The method of reducing interference from natural electric disturbances when receiving radio messages comprising subjectmg received impulses to a plurality of oscillatory circuits each entirely free to oscillate-at its natural period and each resonant to a different frequency, and receiving the desired signal impulses in a circuit tuncd'to a frequency different from each of sai'd circuits. I

2. 'The method of reducing interference fromnaturalelectric disturbances when recoiving radio messages comprising subject ing received impulses to a relatively large number of oscillatory circuits entirely free to oscillate at their natural periods and tuned to undesired frequencies:

3. The combination at a radio signaling station of receiving apparatus and an antenna associated tllerewitl'l, said antenna comprising a series of local circuits, each 5 characterized by a different natural frequency than that employed in signaling to said stat-ion and being perfectly free to osoillate at its natural periodrsaid series containing a ielatively large number of cirenlts as compared to the portion of said antenna associated'with said receiving apps;

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