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Publication numberUS2360726 A
Publication typeGrant
Publication dateOct 17, 1944
Filing dateJun 25, 1942
Priority dateJun 25, 1942
Publication numberUS 2360726 A, US 2360726A, US-A-2360726, US2360726 A, US2360726A
InventorsSetchell Barton T
Original AssigneeSetchell Barton T
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Antenna system
US 2360726 A
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Description  (OCR text may contain errors)

APatented Oct. 17, 1944 UNITED STATES PATENT OFFICE 2,360,726 i f v ANTENNA SYSTEM Barton T. Setchell, St. Paul, Minn.

Application June 25, 1942, Serial No. 448,347

(Cl. 25m-x20) 3 Claims.

My invention relates to an improvement in antenna systems, wherein it is desired to employ the ear-phones or speaker unit of a radio receiving set as the antenna for .the set.

In the use of portable receiving sets, difficulty has been experienced in providing an antennaV and yet which will not interfere with the simple portability of the set. For example when radio receiving sets are carried continuously it has been common practice to either carry an upwardly projecting metal rod or buggy-whip type antenna, or to carry loops, coils, or lengths of antenna wire to be attached in any desired position on the carriers person.

v It is the object of the present invention to provide a radio receiving set which requires no antenna other than the ear phones or speaker unit used in conjunction with the set. As a result no extra antenna wire is required and the problem of attaching a suitable antenna to the carrier is obviated.

I have found that if the ear-phones or speaker unit are separated fromthe output plate terminal by a suitableinductance capable of allowing audio frequencies to pass through and capable of stopping or choking radio frequencies, the earphones or speaker unit may be used as the radio aerial. As a result no extra antenna is required.

A feature of the present invention lies in the provision of an antenna coil which is designed for best reception after the type of phones or speaker and the length of phone cord used has been selected. This antenna coil is connected to the phones or speaker which in turn are connected in any suitable manner with the output from the last tube of the radio receiver through the radio frequency choke coil. The B-battery connection to the plate of the output tube is so arranged that this battery will not short circuit through the phones. This result may be attained either by connecting the positive Bfbattery terminal to the plate through the primary of an output transformer, or by placing a condenser in the circuit between the positive B-battery terminal and the ground.

A further feature of the present invention lies in the provision of a capacitor between the output plate and the radio frequency choke which will permit the by-passing of radio frequencies without substantially alecting audio frequencies.

Theseand other objects and novel features of my invention will be more clearly and fully set forth in the followingspecication and claims.

In the drawing forming a part of my specification: y

v Figure 1 illustrates diagrammatically a receiving setcircuit embodying the use of ear-phones or a speaker unit as the aerial.

Figure 2 isa diagrammatic view showing a slightly different output circuit from that illustrated in Figure 1.

Figure 3 is a diagrammatic View showing another modied form of construction showing the use of a resistor in the output circuit in place of an output coil.

Figure 4 is a diagrammatic View showing a modied form of input circuit.

Figure 5 is a view similar to the remaining ligure, showing another modied form of input and output circuit.

Figure 6 is a diagrammatic view showing still another arrangement of inputk circuit.

The circuit illustrated in Figure -1 of the drawing comprises a radio receiving set which is outlined in general by a broken line and indicated by the letter A. This radio receiving set is illustrated only to show one type of circuit which may be used to embody the principles of the present invention and it should be understood that any other type of receiving set could be substituted for that illustrated.

The radio receiving set A is illustrated as comprising an input tube Ill which may be of the 1T4 type, and the input terminal II is connected to the grid I2 of the tube I0 by a suitable conductor. The plate I3 of the tube I0 is connected by conductor I4 to one coil of the radio frequency transformer I5, the other terminal of which coil is connected by conductor I6 through the resistor II to the positive terminal I9 of the B-battery supply. The'grid 20 of the tube Ill is connected by conductor 2| to the B-battery positive terminal I9 through the conductor I6 and resistor II. The tube filament is connected to a -suitable source of current supply.

`|I'he othercoil of the radio frequency transformer I5 is connected by conductor 22 tothe grid 23 of the mixer tube 24 which may be of the 1R5 type. A conductor 25 connected to the conductor 22 passes through a variable condenser 26 tothe ground. The plate 2'I of the tube 2l'is connected by conductorv 29 to one terminal of one 30. A Yconductor 3I includnga variable condenser 32 extends betweenthe ends of this coil of the transformer A3|). is connected by conductor 33 through the in- V ductance coil 34 and conductor 35 to ther con-Y coil of the intermediate frequency transformer The other coil terminalY ductor I6 leading through the resistor I1 of the positive terminal of the B-battery. The conductor I6 is connected to the ground through a condenser 36.

'Ihe grid 31 of the tube 24 is connected b-y conductor 39 to the conductor 33. The grid 40 is connected by conductor 4| through the resistorA 42 to the ground. A detector crystal 43 is connected between the conductor 33 and the conductor 40.

The other coil of the transformer 3U is connected by conductor 44 to the grid 45 of the intermediate frequency tube 46 which may be of the 1T4 type. The other terminal of this coil is connected by conductor 41 through a resistor 49 to the ground. A variable condenser 50 is connected between the conductors 44 and 41. The conductor 41 is connected to the ground through a condenser The plate 52 of the tube 46 is connected by conductor 53 to one terminal of one intermediate frequency coil of the intermediate frequency transformer 54. The other terminal of this coil is connected by conductor 55 to the positive B- battery terminal I9. A variable condenser 56 is connected between the ends of this intermediate frequency coil and the conductor 55 is connected by a conductor 51 to the grid 59 of the tube 46.

The other coil of the transformer 54 is connected by conductor 6I) to the diode 6| of the tube 62 which may be of the 1S5 type. A variable condenser 63 is connected between the terminals of this coil. The other coil terminal is connected by a conductor 64 through the variable resistor 65 to the ground. The conductor 64 is also connected by conductor 66 through the resistor 61 to the automatic volume control terminal 69. The conductors 64 and 66 are separated from the ground by the condenser 10.

The variable arm 1| of the variable resistor 65 is connected through the condenser 12 and the conductor 13 to the grid 14 of the tube 62. The conductor 13 is connected through the resistor 15 to the ground. The plate 16 is connected by conductor 11 through the resistor |9 to the positive B-battery terminal I9. The grid 96 of the tube 62 is connected by conductor 8| through the resistor 82 to the positive B-battery terminal I9. The conductor 8| is separated from the ground by a condenser 83.

The conductor 11 is connected through the condenser 85 to the grid 86 of the output tube 81 which may be of the 154 type. The grid 86 is connected through the resistor 89 to the negative terminal of the C-battery supply. The plate 9i) of the tube 81 is connected by the conductor 9| to the output terminal 92. The grid 93 is connected by the conductor 94 to the positive B-battery terminal I9. The filaments of all of the various tubes are connected to a suitable current supply.

As was previously pointed out the radio receiving unit outlined by the broken line in Figure l of the drawing is merely illustrative of one form of receiver which may be used, and any suitable receiver may be substituted therefor, as will be clearly understood. The input terminal to the grid of the input tube, the output terminal 92 connected to the plate of the output tube 91, and the positive B-battery terminal I9 are the only essential connections to the various input and output circuits which will be later described. The automatic volume control terminal 69 is ordinarily desirable, but may in some instances not be required. l

'Ihe ear-phones 95 are connected by conductor 96 through the antenna coil 91 to the conductor 99 leading to the ground connection |90 to the coil IUI of the input transformer, which is connected by conductor |62 to the input terminal and is connected by conductor |03 to the A. V. C. terminal 69. The conductor |93 is connected through the condenser |94 to the ground. rIhe conductor |92 isA connected through the: variable condenser |05 to the ground.

The other phone cord or conductor |96 is connected to the radio frequency choke |91, the other terminal of which is connected to the coil |99 of the output transformer, and the other terminal of which is connected by conductor ||9 to the ground. The conductor between the choke coil |91 and the transformer coil `|69 is connected through the conductor I I2 to the ground.

The other coil I|3 of the output transformer has one terminal thereof connected by conductor ||4 tothe output terminal 92 and has its other terminal connected by conductor I |5 to the positive B-battery terminal I9.

It will be noticed that one terminal of the phones passes through the antenna coil 91 to the ground, while the other terminal thereof is connectedthrough the radio frequency choke |91 to the secondary of the output transformer, the opposite terminal of which is grounded.-y The antenna coil 91 is designed for best reception after the length of the phone cords and the type of phones to be used has been selected. The radio frequency choke is any type of inductance coil of such inductance as to allow audio frequencies to pass through and to choke or stop radio frequency passage, The radio frequencies are bypassed to ground through the capacitor I I2 which will not substantially affect audio frequencies.

I have found that with this arrangement the head phones 95 may be effectively used as an aerial and that no other antenna is required. Thus the necessity for a separate aerial is entirely obviated.

In Figure 2 of the drawing I show a slightly different form of output circuit from that above described. In this form of construction the head phones H6 are provided with one cord or conductor |I1 leading through the antenna coil ||9 to the ground. The other coil |26 of the antenna transformer has one terminal connected by conductor |2| to the input terminal leading to the grid of the input tube. A variable condenser |22 is connected between the conductor |2| and the ground. The other terminal of the coil |26 is connected by conductor |23 to the A. V. C. terminal 69. This conductor |23 is connected through the condenser |24 to the ground. Thus the input circuit is similar to that shown in Figure l.

The other phone cord |25 is connected through the radio frequency choke coil |26 which is isolated by the condenser |21 from the conductor |29 leading through the inductance coil |30 to the positive B-battery terminal I9. The conductor |3| between the choke coil |26 and the condenser |21 is connected to ground through the condenser |32.

In this construction it will be noted that one phone cord extends through the antenna coil which is vproperly designed for the particular head phones and length of phone cord used. The other phone cord |25 is connected through the choke coil |26 to the output terminal of the receiving set passing through the condenser |21. The condenser |21 prevents the short circuiting of the B-battery through the headphones, while the choke coil |26 prevents radio frequencies from entering the phones. The condenser or capacitor |32 permits the by-passing of radio frequencies to the ground and is so designed as to not-materially affect audio frequencies.

Another form of output connection is illustrated in Figure 3 of the drawing. In this arran-gement the phones or sound reproducer |33 are connected by a conductor |34 to one terminal of an antenna coil |35, the other terminal of which is grounded as illustrated at |36. The cooperating coil of the antenna transformer, designated by the numeral 31, has one terminal thereof connected by the conductor |39 to the input terminal of the radio receiver A. This conductor |39 is connected through the variable condenser |40 to the ground, the other terminal of the coil |35 is connected by the conductor |4| to the automatic volume control terminal 69. This conductor |4| includes a connection through the condenser |42 to the ground. Thus the input circuit is identical to that illustrated in Figures 1 and 2. The other phone lead |43 is connected through a radio frequency choke coil |44 to the conductor |45.y A condenser |46 is provided between the conductor 45 and the conductor |41, which leads to the output terminal 92 of the radio receiving set. A capacitor |49 is connected between the conductor |45 and the ground. The conductor |50 leads through a resistor to the positive B-battery terminal 9.

It will be noted in this circuit that the B- battery voltage is supplied through the resistor to the output plate and this circuit is segregated from the ear-phone circuit by means of the condenser |46. The radio frequency choke coil 44 is so designed as to allow audio frequencies to pass therethrough while choking or stopping radio frequencies. The capacitor |49 permits the by-passing of the radio frequencies to the ground.

In Figure 4 of the drawing I disclose another modified form of circuit 4which could be used. In this circuit the phones or sound reproducer |52 and one phone cord or lead |53 which is connected to one end of an inductance coil |54, the other of which is connected to a conductor |55 leading to the input terminal The con-I denser |56 is provided between the conductor |55 and the conductor |51 secured to the input terminal. f

battery is connected through the resistor |10 to the output plate of the radio receiving set and this positive battery terminal is segregated from the ground by means of the condenser |66. 'Ihe radio frequency choke coil |64 is so constructed as to pass audio frequencies and to choke or stop radio frequencies. nected between the conductor |65 and the ground capable .of by-passing radio frequencies without materially affecting the audio frequencies. Thus the radio frequencies are prevented from entering the phones or speaker 52.-

In order to illustrate a variety of specific connections which may be made, Figure 5 illustrates another Inodied arrangement. In this circuit the phones or speaker unit |12 have one phone cord or lead |13 which is connected to one side of the condenser |14, the other side of which is connected by conductor |15 to one end of the.

antenna coil |16. The other terminal of the coil |16 is connected by conductor |11 to one side of the condenser |19, the other terminal of which is connected by conductor |80 to the input terminal of the radio receiving set. The conductor |11 is connected to the variable condenser 8| the opposite terminal of which is grounded. A tap |82 to an intermediate point on the coil |16 is also grounded. The conductor |80 is connectedV by the conductor |83 to Vthe A. V. C. terminal 69.

In the event that the radio receiving set does not include automatic volume control it is ob-V vious that the condenser |19 and the conductor |83 may be eliminated, the conductor |11 being directly connected to the input terminal The other phone cord or lead |84 from the phones |12 is connected to one end of the radio frequency choke coil |85, the other terminal of which is connected by the conductor |86 to the output terminal 92 of the radio receiving set. A conductor |81 connected to the conductor |86 1s electrically connected to one terminal of the lcondenser 89, the other terminal of which is leading to the first described phone terminal.

connected intermediate unev ends of the een |54, I provide a'lead |59 which is grounded. The conductor |is also connected through a variable condenser to the ground.

When automatic volume control is used in the radio receiving set the conductor |51 is connected by a conductor |6| through the resistor |62 to the A. V. C. terminal 69. In case no automatic volume control is provided the condenser |56, the conductor |'6|, and the resistor |62 are eliminated, the conductor |55 extending directly to the input terminal e The other phone cord or lead |63 is connected to the radio frequency choke coil |64, the opposite terminal of which is connected by conductor |Yto one side of the condenser |66. The other side of the condenser is connected by conductor |61 to the output terminal l92 of the radio receiving set A. The conductor |61 is also cone nected by a conductor |69 through a resistor |10 to the positive terminal of the B-battery.

It willb e noted VVthat in this circuit the B- Thus in this construction the phones are maintained at B-battery potential and the short cirfcuiting ofthe B-battery is prevented by the condensers |14 and |89.

In this circuit it will be noted that the output plate is vconnected to the phones through the radio frequency choke coil which will allow the passage of audio frequency, but which will choke or stop radio frequencies. Because of the fact that the phones are at B-battery potential, it is also essential to have a second radio frequency choke coil 9| between the positive terminal of the B-battery and the phones or second reproducer |12. The capacitor or condenser |89 allows the by-passing of radio frequencies to the ground.

In Figure '6 of the drawing still another modied form of circuit is illustrated. In this arrangement the phones |93 have one lead |94 ltherefrom connected to one terminal of the antennacoil |95` forming a part of the input transformer |96; The'other terminal of the antenna A capacitor |1| is con- One terminal of the other coil |99 of the input transformer |96 is connected by conductor 200 to the input terminal of the radio receiving set A. The conductor 200 is also connected to the variable condenser 20|, the terminal Yof Which is grounded at 202.

The other terminal of the coil |99 is connected by conductor 203 to the A. V. C. terminal 69 of the radio receiving set. A condenser 204 is connected to the conductor 203 and the other terminal of this condenser is grounded.

The other lead 205 from the phones |93 is connected to the radio frequency choke coil 206, and the other terminal of this coil 206 is connected by conductor 201 to one terminal of lthe condenser 299. The opposite condenser terminal is connected by conductor 210 to the output terminal 92 of the radio receiving set A. A capacitor 2|| is connected to the conductor 291 and the other terminal of the capacitor is grounded. The conductor 2|0 is connected through a suitable inductance 2|2 to the B-battery terminal of the radio receiving set. In this arrangement the output plate is supplied from the positive B battery terminal through the vinductance coil 2|2, and this circuit is segregated from the second reproducer circuit lby the condenser 209. The radio frequency choke coil 296 allows the passage of audio frequency Waves, While choking or stopping the radio frequency Waves. These radio frequencies may be by-passed to the ground by the capacitor 2| I.

In the foregoing description numerous illustrative circuits have been described for the purpose of illustrating that a considerable number of specific hook-ups could be used, While still employing the second reproducerand the leads thereto as an antenna. It should be noted that all of the cir-cuits have certain features in common. In the first place the ear-phones are connected in such a Way that the radio frequency Waves are prevented from passing into the earphones or other sound reproducer. In the second place a capacitor is provided for icy-passing radio frequency Waves. In the third place the B-battery circuit to the plate of the output tube is so arranged that the short circuiting of the B-battery through the second reproducer circuit is prevented.

For the purpose of simplicity I have used the term sound reproducer in the claims in place of calling for ear-phones or a speaker unit. While ear-phones are ordinarily used with the portable sets for which this arrangement is particularly adapted, speakers are sometimes used, and such speaker could be used in place of the ear-phones described. For this reason the term sound reproducer is meant to designate any sound reproducer element, such as ear-'phones or a speaker unit.

In accordance with the patent statutes, I have described the principles of construction and operation of my antenna systems, and While I have endeavored to set forth the best embodiment thereof, I desire to have it understood that these are only illustrative of a. means of carrying out my invention, and that obvious changes may be made Within the scope of the following claims Without departing from the spirit of my invention.

I claim:

1. A radio receiving system comprising in com- :'bination, a receiver having a radio frequency input circuit including an antenna coil having coupled primary and secondary portions, detecting and amplifying tubes, and an audio frequency out-put circuit including an out-put transformer, ear phones, a radio frequency choke coil connected in series between one terminal of the ear phones and one terminal of the out-put transformer secondary, the other terminal of said secondary being grounded, a by-pass circuit connected to said one terminal of said out-put transformer secondary, including a capacitor of a size to by-pass radio frequencies and not to by-pass audio frequencies, and said choke coil being of proper size to separate the radio and audio frequencies and to prevent the radio frequencies from being grounded or bypassed to ground through the secondary of the out-put transformer or the capacitor, and means connecting the other terminal of said phones to one terminal of the antenna coil primary portion, the other terminal of the said primary portion being grounded, whereby radio frequency potentials impressed upon the named circuit elements and connections are applied to said receiver input circuit through said secondary portion.

2. In a radio receiving system having a radio frequency input side and an audio frequency out-put side, an antenna transformer having a primary Winding arranged to transmit radio frequency signalling impulses to the input side, an out-put transformer connected to the audio frequency out-put side, ear phones having one terminal thereof connected in series through a radio frequency choke coil to one terminal of the out-put transformer secondary, the other terminal of ths vtransformer secondary being grounded; a by-pass connected to said one terminal of said transformer secondary and ground and including a capacitor capable of by-passing radio frequencies and not by-passing audio frequencies, said choke coil constructed to stop radio frequencies from being grounded or bypassed to ground through the secondary of the out-put'J transformer or the capacitor; and means connecting the other terminal of said ear phones to one terminal of the primary Winding of said antenna transformer, the other terminal of said primary winding beingl grounded, thus completing both radio frequency and audio frequency circuits.

3. In a radio receiving system having a radio frequency input side and an audio frequency7- out-put side, an antenna transformer having a primary Winding arranged to transmit radio frequency signalling impulses to the input side, an out-put transformer connected to the audio frequency output side, sound reproducing means having one terminal thereof connected in series through a radio frequency choke coil to one terminal of the out-put transformer secondary, the other terminal of this transformer being grounded; a 'by-pass connected to said one terminal of said transformer secondary and ground and including a capacitor capable of by-passing radio frequencies and not by-passing audio frequencies, sai-d choke coil constructed to stop radio frequencies from being grounded or by-passed to ground through the secondary of the out-put transformer or the capacitor; and means connecting the other terminal of said sound reproducing means to one terminal of the primary winding of said antenna transformer, the other terminal of said primary Winding being grounded, thus completing both radio frequency and audio frequency circuits, Y

BARTON T. SETCHELL.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2496424 *Jul 10, 1946Feb 7, 1950Raytheon Mfg CoRadio tuning device
US5361405 *Nov 30, 1990Nov 1, 1994Ramsey Electronics, Inc.Aircraft band radio receiver which does not radiate interfering signals
DE974259C *Sep 29, 1954Nov 10, 1960NordmendeUltrakurzwellenempfaenger mit mehreren Lautsprechern
DE3125202A1 *Jun 26, 1981Apr 22, 1982Sony CorpRundfunkempfangsgeraet
Classifications
U.S. Classification455/270, 343/722, 455/292, 343/850, 343/720
International ClassificationH04B1/16
Cooperative ClassificationH04B1/16
European ClassificationH04B1/16