US2378663A - Radio receiver - Google Patents

Description

June 19, 1945. i sTRlKER 2,378,663

' RADIO RECEIVER- Filed Jan. 16, 1942 Sheets-Sheet 1 RH! ION 4974575 EVE M5 1 BEID/ I I I annals Amman AND V zsumns cvuima l 9 umns ALL DAY ISMETEB mums U 1 W DIAL .June 19, 1945. G. o. STRIKER Q RADIO RECEIVER Filed Jan. 16, 1942 5 Sheets-Sheet 2 2E wmm June 19, 1945. G. o. STRIKER RADIO RECEIVER Filed .Jan; 16; 1942' 5 Sheets-Sheet 3 IIIIIIIIIIAl ll'llll 3 6 H. M w 7 2 m m X, d w 6%% 2 4 I I I I ll. mm L. Mm I I I I I I R I 1 Tm :1 s n .m& s mm.

June 19, 1945.

Patented June 19, 1945 RADIO RECEIVER George 0. Striker, Chicago, 111., assignor to Zenith Radio Corporation, Chicago, 111., a corporation of Illinois Application January 16, 1942, Serial No. 426,991

43 Claims.

and other forms or interference.

A further object of the invention is to provide a radio receiver with a, short wave loop antenna which may be located at positions relatively remote from the receiver.

A further object of the invention is to provide means for tuning the loop to adapt it for the reception of signals in different bands.

A further object of the invention is to provide a radio receiver with a plurality of antennae with means whereby the preparation of one antenna for use renders another antenna inoperative.

A further object of the invention is to provide a radio receiver having a fish-pole antenna and switch means controlled thereby connecting and disconnecting said antennato the input of the receiver and for connecting and disconnecting another antenna from the input of the receiver.

Other objects, advantages and capabilities of the invention will appear from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, in which:

Figure l is a perspective view showing the manner in which the portable radio receiver may be used by a railroad passenger;

Fig. 2 is a front elevational view of the receiver, the front cover being opened;

Fig. 3 is a rear elevational view, the rear cover being removed to show internal parts;

Fig. 4 is a sectional detail taken on the line 4-4 of Fig. 3 showing the telescoped fish-pole antenna in cross-section and associated elements in elevation;

Fig. 5 is a front view of the mechanism shown in Fig. 4;

Fig. 6 is an elevational view of the two-loop antenna structure, a cover of the short wave loop being removed and an associated part thereof being shown in section;

Fig. 'I is a fragmentary plan view thereof on a somewhat larger scale;

Fig. 8 is a wiring diagram of the receiver;

Fig. 9 is a fragmentary rear view of the receiver with the rear cover removed, showing a modified form of fish-pole antenna;

Fig. 10 is an elevational view partly in section of such fish-pole antenna in collapsed form; and

Fig. 11 is a view similar to the left-hand side of Fig. 6 showing a modified form of short wave antenna. 4

Referring to the drawings, the radio receiver as a whole is contained within a case 20 which is provided with ahinged front cover 2|. When the front cover 2| is opened, music and other broadcast material may be emitted from the loud speaker 22.

Adjacent the loud speaker 22 is a panel 23 which serves as a mounting for tone controls 24, a tuning control 25, and a volume control 26. The tone controls 24 open and close the four switches 21 in Fig. 8 to effect control of the tone. The tuning control 25 controls a gang of condensers 28, 29 and 30 for tuning the RF input circuit, mixer input circuit, and oscillator circult, respectively (Fig. 8).

The volume control 26 controls the double-pole single-throw switch 3| (Fig. 8), and the volume control 82 also shown in that figure. The tuning control actuates not only the gang of condensers but also the pointer 33 of the dial 34.

The dial 34 comprises indicia 35 corresponding to the broadcast band and five sets of indicia 36 which correspond to five short wave bands, for example, the 16-meter, the 19-meter, the 25- meter, the 31-meter, and the 49-meter bands.

Adjacent the dial it is an escutcheon plate 31 which carries a series of projecting switch buttons 38, 39, 40, ll, 42 and 43, corresponding to the broadcast bands just referred to.

As best seen in Fig. 2, the escutcheon plate 31 bears opposite these buttons the name of the corresponding band and also indicia adjacent the buttons indicating when the best reception is received with that band. Thus, the best reception of the 49-meter band is in the evening, with the 31- and 25-meter bands in the afternoon and evening, the l9-meter hand all day, and the IG-meter'band in the morning.

The double-pole single-throw switch 3| controls the supply of electrical energy to the tubes of the receiver. This energy may be supplied by A and B batteries 44 and 45 (Fig. 8) carried in the receiver case or it may be supplied :by the plug 46 which may be inserted in any available wall receptacle, the power pack associated therewith being arranged for A. C. and D. 0. operation. This power pack includes a rectifier tube 4.1 and the filter instrumentalities illustrated in Fig. 8.

The receiver may be changed over from battery to power line operation by means of a fourpole double-throw switch 46 shown in power line position in Fig. 8.

The band switch buttons 56 to 43 constitute the outer ends of axially movable switch bars bearing the same numbers and shown in Fig. 8. In this figure two views of each switch bar are shown in relatively inverted relation. Thus, if one of the switch bars were actuated in Fig. 8, then the upper showing of that bar would be displaced upwardly while the lower showing of that bar would be displaced downwardly.- The black parts of the switch bars represent insulation and the white parts conducting material.

The bars 88 to 43 are associated with a looking bar 49 of known type shown diagrammatically in Fig. 8. This locking bar is so arranged that it holds any bar which is displaced inwardly in its inward switching position. The bar is so arranged that it is actuated to releasing position by the inward movement of another bar. Consequently, only one of the band switches 36 to 43 is operative at any time.

The receiver may suitably be a superheterodyne receiver, tube 50 being a radio frequency amplifier, tube 5|, the mixer, tube 52, an intermediate frequency amplifier, tube 58, a detector and audio amplifier, tube 54, a power amplifier, and tube 55, the oscillator tube.

The receiver is provided with a, plurality of antenna structures which will now be described. For broadcast pickup, a loop antenna 58 of the type described and claimed in Patents Nos. 2,164,- 251, 2,200,674, 2,237,260, and 2,250,387, issued to Eugene F. McDonald, Jr., may be employed.

The loop 56 is enclosed within a suitable nonconductive enclosure 51 which is hinged to plate members 58. These plate members 58 carry suction cups 59 whereby the loop may be mounted on the glass window 60 of a conveyance. This conveyance may, for example, be a steel railroad car, a bus, an airplane, or an automobile. Of course, the invention is not intended to be limited to a conveyance since its antenna may be used to great advantage in a steel or metallized house, or it may be used irrespective of any enclosure whatsoever. Normally, the suction cups 59 do provide a very simple quickly attachable and detachable means for supporting the loop 56 on or near a dielectric wall such as a pane of glass in an enclosure which is constituted for the most part by walls of conducting material. It is within the scope of my invention to provide one or more suction cups to support loop 66.

The ends of loop 56 are connected to two leads 6| and 62, lead 62 appearing in Fig. 8 as the outer conductor of a coaxial cable having a center conductor 8|. For the purposes of the broadcast loop 56, it is important that the distributed capacity between the leads 6| and 62 should be maintained low and should be maintained substantially constant. For this reason the conductor 8! and its shield 62 are located along one edge ofa stout ribbon 82 and the conductor 6| is located along the opposite edge of this ribbon. This ribbon is relatively broad and still so that the spacing between the conductors at the opposite sides is maintained substantially constant. The latter lead is connected to a small loading coil 63 on a five-prong plug 6|. The five prongs are shown as ringed dots in the upper left-hand corner of Fig. 8. The conductor 6| is connected to one prong. The coil 63 is connected to another. A tap on this coil is connected to still another prong.

On the receiver is mounted a three-position switch 65 which in one position shorts the upper part of the coil 63 and in another position introduces a small capacity 66 across the leads 6| and 62. In its intermediate position the switch 65 has no eliect on the inductance or capacity of the circuit including the loading coil 63 and the loop 56. The purpose of the switch 65 is to introduce a slight correction for improving the tuning of the loop 56 which may be impaired by mounting the loop too near the edge of a steel window, for example, or from some other cause. The capacity 66 may suitably be constituted by a few turns of wire around the conductor leading to conductor 5| as is illustarted in Fig. 8.

The housing 51 also, contains a coil 80 of a few turns in close proximity to the loop 56, the ends of the coil 60 being connected to terminals 9| and 92. In the case of a semi-permanent installation, for example in the case of a sojourn at a country home, it may be desirable to operate with an outside aerial which may be connected to the terminal ill, the terminal 92 being grounded. It will thus be seen that the coil 90 is coupled to the loop 56 and that the operation for broadcast reception with an outside aerial is attained in a remarkably simpler manner.

For short wave reception the loop antenna 56 is no longer suitable. An antenna having a low inductance and capacity is required. In accordance with the present invention, I provide a short wave loop antenna 61 which consists essentially of a few turns of wire extending around a U- shaped dielectric tube 68. The tube 66 has its ends mounted in a housing 69 which is hinged to the plates 58 as best seen in Fig. 6.

If the loop 61 were not tuned separately from the receiver and were located at a point remote from the receiver, the inductance and capacitance of the connections between the loop and receiver, especially at high frequencies, would seriously mistune the loop. In fact, such a loop with its connections to the receiver would probably be resonant at a relatively low frequency. By providing a small degree of coupling between loop 61 and the receiver input circuit it is possible to eliminate the mistuning effect of the connections sufilciently that the loop 61 may be tuned substantially independently of the receiver even at high frequencies. In accordance with this invention, adjustable tuning means is provided at the loop to tune the loop to any desired frequency. Such an arrangement is shown in Fig. 8. Opposite ends of the loop 61 are connected across a condenser 10 which is arranged to tune the loop to a desired frequency within one of the short wave bands. A three-position switch H is arranged to cut in a condenser 12 or a condenser 13 into parallel connection with the condenser 10 so as to tune the loop for two other short wave bands of longer wave length.

When using a short wave loop such as loop 61 it is even more desirable than with the broadcast loop 56 to provide a relatively long transmission line for connecting the loop remotely to the receiver input so that the loop may be placed in a position removed from the receiver. This is so because at high frequency the conductors of the receiver itself if too near the loop, shield or damp the loop even more so than at lower frequencies and render it less effective to transmit a signal to the receiver input. At the same time, the use of such a line becomes more dimcult at high frequencies because of radiation loss from and radiation pickup on the transmission line itself. Also, the problems of shunt and stray capacity of the transmission line, discussed in connection with the broadcast loop ll, become more troublesome. For the purpose of transmitting signals intercepted by the short wave loop 91 and transferring the same to the receiver located remotely from the antenna, and more specifically for transferring intercepted signals to a control grid of the mixer tube 6|, there is provided a link circuit extending in space from the loop 61 to the receiver and comprising a first coupling coil 18 coupled to the loop 81. a Pair of conductors 62 and 8|, a, switch Hi0, and three coupling coils l4, l and 16, all connected in series relation. The coil 18 suitably comprises a single turn of wire positioned closely to the loop antenna 61 and preferably has a common point therewith. The loop antenna 61 and the coil 19 thus form a step down transformer.

The switch Hill is closed when using the receiver with the short wave antenna 61 and is actuated by the flshpole antenna 93 as will be explained hereinafter. The coils 14, I5 and 16 are located at the receiver and coupled to coils 42a, Ma and 40a, respectively, which can be connected in circuit with the tank circuit comprising the secondary winding of transformer m and variable condenser 29 for the purpose of applying the signal intercepted by the antenna 61 to a control grid of the mixer tube 5|. The variable condenser 29 tunes the tuned circuit IM, 29 to the same signal frequency as that to which the loop 81 is tuned. Tuning of the receiver input as well as the loop increases the selectivity of the set in an amount proportional to the product of the quality factors of the two tuned circuits. This is desirable for best operation of a superheterodyne receiver.

Since the coils l4, l5 and 16 each have a smaller number of turns than the coils 42a, lla-and 40a, respectively coupled thereto, there is an upwards transformation of voltage therebetween. The voltage transformations, down at the antenna and up at the receiver at the opposite ends of the link circuit results in good energy transfer and yet permit the transmission line to operate at a lower voltage thereby reducing the effect of the shunt and stray capacity of the line. Furthermore, this transformation produces a better impedance match between the high impedance tuned antenna circuit and the untuned transmission line, and between the line and the high impedance tuned input circuit of the receiver. In the specific embodiment of the invention shown, the loop antenna 61 is arranged to operate on the 3l-meter, the 25-meter, and the iii-meter.

bands, these being the bands controlled by the switch bars 40, 4| and 42, respectively. It will, however, be understood that any desired number of condensers may be provided so as to be brought into parallel relation with the condenser Ill and the windings I4, 15 and 16 should be likewise increased in number. 7

Thus, I may provide, instead of the switch 1|, a five-position switch, and provide two condensers in addition to 12 and I3, arranged to be connected in parallel with the condenser 10 by the five-position switch. In addition, twowindings in series with the windings I4, and 19, would be provided in the same relation with the coils associated with the bars 39 and 43 as the cells l4, l5 and I6 bear to the coils associated with the bars 42, 4|, and 40, respectively.

The switch H is mounted on the housing 69 and is provided with a projecting button ll (Fig. 6). It will, of course, be understood that suitable indicia (not shown) is associated with the button 11 so as to indicate the particular short wave The edge of the wheel 19 projects out of the housing 99 so that it can be actuated manually to provide a slight adjustment of the condenser 10. This slight adjustment corrects for variable capacity effects introduced by variable mounting of the loop relative to conductors such as the body of a steel car.

The connection of the loop 61 and the coil 18 of the link circuit to the receiver will now be described in detail. The connections comprise a common conductor 82- which is a shield. This shield extends to the plug 84 where it is connected, as previously indicated, to one end of the loading coil 63 and to the fifth prong of the plug.

Within this shield is a conductor 0| which is connected to the other end of the coil 19. This conductor is connected to the fourth prong of the plug 84. The shield 82 and conductor 9| form a coaxial line. Of course two separate wires may be used, if desired, but the shielded line provides one of the simplest means of achieving the desired characteristics of the transmission line, namely, low signal radiation loss and stray radiation pick up, and relatively low shunt capacity. Of importance, for obtaining suitable signal pickup in a shielded structure, is the tuned loop antenna winding 81 which is coupled through an untuned link circuit to the input circuit of a receiver tuned to the same frequency as is the loop antenna.

The composite link circuit includes the first coil 18 on one end of the conductors 82, ill and on the other end the serially connected coils 14, I5 and 18 which, for purposes of analysis, may be grouped and considered as a second coil serially connected with said first coil 18 through the elongated conductors 92, 9| comprising, preferably,

the co-axial cable, as shown in Figure 6.

Coil 18 is mounted near to and coupled to antenna 91 directly through transformer action, the winding of antenna 91 serving as one element of the transformer. and coil" serving as the other element of the transformer. This type of coupling is preferred, inasmuch as a minimum number of circuit elements is necessary and efficiency of energy conversion is high.

Of importance in short-wave reception, is that tuning of the antenna 91 and tuning of the input circuit of the receiver results in high selectivity andhigh image ratio. This is especially desirable at high frequencies.

Furthermore, the particular arrangement of the link circuit with the tuned loop antenna and tuned receiver input circuit results in a decrease in both'the inductance at the loop antenna and at the input circuit of the receiver, in accordance with the principles set forth in "Radio Engineer's Hand Book, by Frederick E. Terman, 1943, published by McGraw-Hill Book Company.

Furthermore, inasmuch as the over-all co-eiilcient of coupling between the tuned loop antenna 91 and the tuned input circuit of the receiver is quite small, the tuned loop antenna 81 is coupled in small degree to the tuned input'circuit, as is evidenced by the constructions shown in Figs. 6. 8 and 11. It is remembered that the co-efiicient of coupling between two circuits is a ratio and is defined as the ratio of the mutual inductance actually present between two windings to the maximum possible value that can occur. In accordance with this accepted definition of the co-eiiicient of coupling. the magnitude of the coupling between loop antenna 81 and adjacent link circuit coil 13 in Figs. 6 and 11 is in the range of .15 to .25.

The co-efiicient of coupling between the tuned input circuit of the receiver and the adjacent link circuit coil, comprising, in fact, three coils I4, 15 and 16, has as its maximum possible theoretical magnitude one-third or .33, inasmuch as the flux from only one of such coils 14, 13 and I6 threads the magnetically coupled input circuit of the receiver. As shown by Fig. 8, the secondary coils 43A, HA, and 42A are. respectively, close to their associated iron cores, and primary coils 16, I and I4 are spaced a substantial distance from the corresponding secondary coils and cores. Therefore, the co-efflcient of coupling between each of the coils 16, I5 and I4 and its associated secondary coil is substantially less than unity, with the result that the co-eiilcient of coupling between the link circuit coil comprising serially connected coils I4, 15 and I6 is substantially less than the possible theoretical maximum magnitude of .33.

In accordance with a commonly accepted deiinition of loose" and "tight coupling, as set forth in the above-mentioned "Radio Engineer's Hand Book, these recited magnitudes of the various coupling co-eiiicients of .15 to .25 and .33 neither correspond to tight" coupling nor to "loose" coupling, inasmuch as such publication states that closely coupled coils usually have a coupling co-eflicient of .5 or greater, and loosely coupled coils have a coupling co-eiiicient of .01 or less. Thus, these two magnitudes of .15 to .25 and .33 fall within a range which, for purposes of this specification, corresponds to a state of medium coupling.

The short-wave loop antenna shown herein is thus not tightly coupled to the input circuit of the receiver upon consideration that the overall coupling is the product of the individual coupling co-eiiicients and which has a maximum product of .25 .33 or .0825. Of course, this actual magnitude of .0825 for the over-all coupling co-efficient is the maximum theoretical magnitude and, for the reasons explained, is smaller in actual physical receivers embodying apparatus having the precise arrangement of elements shown herein.

This small degree of coupling, which gives emcient energy transfer consistent with high selectivity and good image ratio, is desirable not only for the reasons stated above including making it possible to tune the loop 31 substantially independently of the receiver but also because it makes possible the use of a critical amount of coupling which by definition is the condition for maximum energy transfer. In accordance with the present invention, I also provide a fish-pole or extensible rod antenna 33 which is normally housed in telescoped and unerected position, as shown in Fig. 3, the fish-pole antenna being then located in the rear of the housing. To render the fish-pole antenna operative, the rear door of the receiver housing is opened and the telescoped fish-pole antenna 93 is swung into vertical position, that is, the positionin which it is shown in dottedlinesinl'ig.3. Ibrtbispurpocethelowasvaees ermost section of the fish-pole antenna 33 is rigidly arried on a lever 34.

The lever 34 is pivotally mounted on a bracket 35 secured to one side of the case 23 of the re ceiver. When the fish-pole antenna 33 is erected, its lowermost section is brought into registry with two semi-circular openings 30 in the upper wall of the case 20 and on the upper edge of the rear door thereof so that this door may now be closed, leaving the fish-pole antenna projecting upwardly from the case in the vertical direction. It will, of course, be understood that the fish-pole antenna may be pulled out or extended in normal manner, illustrated in Fig. 9, with respect to a modified arrangement of fish-pole antenna.

Referring to Figs. 4 and 5, it will be readily understood that when the lever 04 is swung by the movement of the fish-pole antenna 33 into erected position, one end of the lever 34 engages a projection 31 and moves it upwardly, thus displacing contacts 33. II and III. upwardly. These contacts are elements of the three switches 33, 93 and Hill shown in Fig. 8. These switches are shown in Fig. 8 in the condition in which they are after the fish-pole antenna has been erected. It will be understood that when the fish-pole antenna is again unerected or turned into horizontal position, the switches I3 and II assume their different positions and the switch I 03 becomes closed.

In the embodiment of the invention shown in Figs. 9 and 10, a different fish-pole antenna I23 is employed. This fish-pole antenna has a lower section I2I which is fixedly mounted within the case 23 of the receiver. As shown in Figs. 9 and 10, the fish-pole antenna comprises a plurality of sections which can be telescoped together. When fully telescoped, the knob I22 of the fishpole antenna projects from the upper side of the case 23 as shown in dotted lines in Fig. 9. The fish-pole antenna may, of course, be extended fully or to a desirable degree by merely grasping the knob I22 and pulling it upwardly.

The innermost section of the fish-pole antenna consists of a rod I23 which is somewhat longer than the other sections of the fish-pole antenna. Consequently. when the fish-pole antenna is fully telescoped back into the case 23, the rod I23 projects beyond and below the lowermost section III. In this embodiment of the invention the switch elements 93, l0 and I" are adapted to be actuated by the movement of a projection 31, this projection having a portion extending below the fish-pole antenna so as to be actuated by the rod I23. The projection 31' is biased upwardly by suitable springs.

It will readily be understood that when the knob I22 is moved upwardly from its normal position and when the knob I22 is returned to its normal position, the same switching operation eifected by the erection and reclining or the fishpole antenna 93 will take place.

The loop antenna shown in Fig. 11 differs from the loop antenna I! primarily in that it consists of two turns I 24 of relatively stin wire. This wire is sufficiently strong so that it does not need to be enclosed in a dielectric tube as shown in the previously described embodiment.

The two turns I24 are supported where they enter the housing 33 by means of two bushings I25 of suitable dielectric material. The two loops I24 are further secured together preferably at a position remote from the housing 33 by means oi a suitable block or spacer I2! of insulating material. The remainder of the elements associated with the loops I24 may be precisely the same as in the previously described embodiment.

The operation is as follows: To prepare the receiver for battery operation, the four-pole switch 48 is thrown to the right, as viewed in Fig. 8, and the double-pole single-throw switch 3| is closed, supplying electrical ener y to the tubes. On the other hand, if it is desired to operate from power lines with A. C. or D. C. current, the plug 48 is plugged into a suitable outlet, the switch 48 is thrown to the left, as viewed in Fig. 8, and the switch 8| is used as an on and off" switch as it was when the receiver was battery operated.

For operation in the broadcastband, the antenna employed is selected in accordance with the location. At the beach .or at a football game, it is preferred to employ the fish-pole antenna 88 for this puropse, whereas on a train or in a metal airplane, or indeed in any partially shielded structure or in any location where there is a large amount of man-made static, better results will be obtained with the loop 58.

Operation with the loop 56 will first be described. The loop 56, together with the loop 81, is mounted by means of the section cups 58 at a suitable location on a train window as shown in Fig. 1. Considerable improvement in reception can usually be obtained by slight changes of the mounting position on the window and changes of orientation of the loop relative to the window.

The broadcast bar 88 is pushed inwardly and tuning is effected by means of control 25, the

' volume being controlled by the button 28 which actuates the switch 8|. The tuning is indicated on the scale and indicia 85, this being the broad cast scale.

Reception is improved by orientating the loop 55 relative to the plates 58 whereby the loop is brought into the best plane for reception. Reception may be improved further by operating the switch 65 into the best of its three positions.

Since the fish-pole antenna 83 is in its unerected position, the switches 88 and 88 are in their other positions from those shown in Fig. 8, switch I being closed.

Consequently, conductor 6| is connected directly to the control grid of the RF amplifier tube 50. The loop is tuned by the condenser 28 of the gang of condensers, the other side of the condenser 28 being connected through loadin coil 83 to conductor 82.

Since the broadcast bar 38 has been actuated, its upper portion in Fig. 8 is displaced upwardly and its lower portion in that figure is displaced downwardly. As a result of the upward displacement of the bar 38, the high side of the secondary of the radio frequency transformer I0| is connected through condenser I02 to a grid of the mixer tube 5|. Unless the bar 38 is pushed inwardly, this connection is not made and consequently no broadcast signal can pass from the radio frequency tube 500 to the mixer tube 5|.

It may be noted that the condenser I02 is relatively large being, for, example, a .02 microfaraci condenser. On the other hand, the condenser I08 which connects the high side of the secondary of the transformer |0| to the condenser I02 is very small, having a capacity of around 15 micro-microfarads. Thus at broadcast frequencies the condenser I03 is not large enough to couple the secondary of transformer |0I to the mixer tube 5|. Condenser I03 is used in short wave reception as will be described. The actuation of the bar 38 shorts the condenser I08.

The actuation of the bar 88 tunes the oscillator tube 55 to an appropriate frequency band. The

vquency tube 50.

grid of this tube is connected through condenser I04, contacts I05 and I05 to the tank circuit I01, the other side of which is connected to radio frequency ground. Radio frequency ground is determined by condenser I08 which may suitably be a .1 microfarad condenser. The cathode of the tube 55 is connected thereto through condenser I08 which may suitably be a .07 microfarad condenser. The plate of the tube 55 is connected through condenser H0 and contacts .III and H2 to a coil III coupled to the tank circuit I01.

The same circuits are established when an ouii'idggr aerial is employed with the aid of the co Employing the fish-pole antenna 88, the erection of the fish-pole or its extension in the case of a fish-pole of the second described variety. moves the switches 88, 88 and 00 into the positions in which they are shown in Fig. 8. The circuit of loop 58 is now broken and signal passes from the flshpole antenna 88 through switch 88, through contacts on the actuated bar 88 up to the tap on coil 4 to radio frequency ground.

Condenser H5 is a trimmer to compensate for variations in fish-pole circuit capacities. The signal energizes the circuit including coil 4 and tuning condenser 28, the high side of which circuit is connected to a grid of the radio fre- The oscillator circuit is as previously described.

The fish-pole 88 can also be employed in the case ofall the short wave bands. In this connection it is pointed out that when operating on any of the short wave bands, the broadcast bar 88 is in its outer position, so that no broadcast signal from the loop 58 can pass to the mixer as has previously been described. At short wave frequencies the loop 58 is substantially shorted so that substantially no short wave signal passes from tube 50 to tube 5| even though they are (iglalpled at these frequencies through condenser If the button 43 is actuated, the fish-pole signal passes to coil 48a, the low side of which is connected to radio frequency ground. The high side of the coil 43a is connected through the unactuated bar 88 and through coupling condenser I02 to a grid of the mixer tube 5|. At the same time the high side of the coil 43a is connected through the relatively small condenser I08 to the high side of the tank circuit including'the secondary of the transformer IOI and the tuning condenser 28. The condenser 28 tunes the signal input circuit of tube 5| in coordination with the tuning of the oscillator circuit. The coil 43a thus forms a part of a circuit tuned to the signal frequency.

The actuation of the bar 48 (lower portion in Fig. 8) connects the circuit of the grid of oscillator tube 55 to-the upper end of coil 48b, the lower end of which (actually a tap) is connected to radio frequency ground.

At the same time the plateof the oscillator tube 55 is connected through condenser H0 and the bar 43 to the coil 480 coupled with coil 48!), the other end of the coil 48c being connected to radio frequency ground (actually the same tap).

The grid of the oscillator tube 55 is connected through condenser I04 and contacts I05 and 8 on the unactuated bar 88 to a condenser Ill. The condenser III is connected to radio frequency ground by a condenser II 8 and it is also connected by contacts III and I on the unactuated bar 38 to the tank circuit I01. This permits the use of condenser 30 as a band spread tuner. Since this condenser is in series with the small condenser II! and is shunted by fixed condenser II8, the effect in change of capacity when condenser 30 is varied is, therefore, very small. The oscillator frequency is thus tuned by the variable condenser 30 to give an appropriate oscillator frequency for this band.

Similar results can be obtained with the bars 42, ll and 40. the associated coils being indicated 42a, 42b, and "c, etc.

The bar 89 controls an oscillator circuit in precisely the same way as the bars 40 to 03, coils corresponding to 4012, 40c being designated 30b and 39c, respectively. The fish-pole signal, however. goes through the coil 39a to radio frequency ground. This coil is inductively coupled to a winding 38d, thus decreasing the coupling of the fish-pole-to the input circuit. The winding 39d is connected through the two uppermost contacts on bar 38 (Fig. {3) through condenser I 02 to the grid of the mixer tube SI and throu h condenser I03, to the tank circuit including the secondary of transformer I M and the tuning condenser 29.

When the button 38 is not in actua ed condition and when the fish-pole antenna 83 is in its unerected osition or the corresponding fish-pole antenna I20 is in fully telescoped condi ion. both the loop 56 and the fish-pole are rendered inoperative. In the first case. the hi h side of the secondary of the transformer IOI is effectively disconnected and in the second case the switch 99 is opened.

The receiver is now in condition for o eration by the loop 61 (or the e uival nt 1000 I24). It is to be noted that the switch I M is closed when the fish-pole is stowed away. This switch may be omitted if desired since when the fish-pole antenna is in operation. the two locus 50 and 61 are stowed away in the back of the case 20. At the hi h frequencies for which the loop 61 is suited, this loop is substantially shielded by the other nearby conductors in the case and is not in the least effective. However. in some cases it is preferred to use the switch I00 and if it is used. it must be closed when short wave loop reception is desired.

The loop 81 being mounted on w ndow 60 of a railroad car. for exam le. it is orientated manually to give best reception and the button I0, I or 42 is pushed in accordance with the band which it is desired to receive.

The switch II is moved into the corres onding position to select the same band. this switch being located on the housing 69 of the loop 61 as has been previously described. 1

The receiver is. of course. turned on by the switch 3| on the volume control 20 and tuning is effected by means of the button 25 to bring in the desired station. Control wheel I9 may then be adiusted to tune the loop 01 accurately within the selected band to the station manually selected by button 25. Slight correction for variation of capacity of the loop 01 by reason of varying position on the window 00 is also readily taken care of by actuating the control wheel 19 of the condenser I0.

The signal from the loop 01 is conveyed through the link circuit which includes the coil I0, the leads 02 and 8| and the coils I4, I! and IS. The signal is transferred from the appropriate one of these coils to the coil "a, "a. or a, depending upon which of the three buttons 42, 4| or 40 is in the actuated position.

As has previously been explained, one end of each of the coils 42a, Ila and 40a is connected to radio frequency ground and the high sides of these coils are connected, when their respective buttons 42, H and 40 are pushed, to the grid of the mixer tube BI and to the tuning condenser 29 in the manner previously described in connection with short wave operation with the fishpole antenna.

Although the invention has been described in connection with specific details of preferred embodiments thereof, it must be understood that such details are not intended to be limitative of the invention except in so far as set forth in the accompanying claims.

Having thus described my invention, I declare that what I claim is:

1. In combination, a radio receiver, said receiver having an input circuit, a loop antenna winding spaced a substantial distance from said input circuit, a low impedance untuned hnk circuit extending between said input circuit and said antenna winding and arranged to transfer radio frequency energy therebetween, said link circuit including a coil having less turns than said antenna winding, means mounting said antenna winding and coil in close proximity to one another such that said antenna winding and coil comprise elements of a transformer, and means for tuning said input circuit to a frequency equal to the frequency at which said antenna. winding is tuned whereby radio energy is efficiently transferred between said antenna winding and link circuit and variations of stray capacity of said link circuit produce no substantial effect on transfer of such radio energy.

2. In combination, a radio receiver, said receiver having a plurality of input circuits tunable to the frequency of signals in any one of a plurality of bands in a relatively large frequency spectrum, means for tuning said input circuits, each of said input circuits including a coil, a loop antenna arranged to be mounted remotely from said receiver, means proximate to said loop for tuning it to a predetermined resonant frequency corresponding to a frequency in any one of said plurality of bands, a low impedance untuned link circuit arranged to pass signals in all of said bands and coupling said loop antenna to said coil of each of said input circuits, and means for selectively connecting one of said tunable input circuits to said receiver for the transfer of signals from said link circuit to said receiver.

3. In combination, a portable radio receiver unit having an input circuit, a coil connected in said input circuit for the transfer of energy to said unit, means for tuning said coil to a frequency desirable for operation of said radio unit, a short wave loop antenna arranged to be mounted remotely relative to said unit, means proximate to said loop for tuning it to a predetermined resonant frequency equal to the first mentioned frequency, an untuned link circuit coupling said loop antenna to said coil in,said input circuit, said link circuit comprising: a two-conductor cable extending from said loop antenna to said unit and having its conductors connected to opposite terminals of a first coil coupled to said loop antenna for voltage stepdown from the loop to said first coil and having its conductors connected to a second coil coupled to said coil in the input circuit, for the transfer of signals received in said loop antenna to said input circuit.

4. In combination, a radio receiving unit, a plurality of input circuits tunable to the frequency of signals in any one of a plurality of bands, each of said input circuits including a coil, means for tuning said coil to a frequency desirable for operation of said radio unit, a loop antenna arranged to be mounted remotely from said unit, means proximate to said loop for tuning it to a predetermined resonant frequency equal to the first mentioned frequency and corresponding to a frequency in any one of said plurality of bands, 3, low impedance untuned link circuit coupling said loop antenna to said coil of each of said input circuits, said link circuit comprising: a twoconductor cable extending from said loop antenna to said unit and having its conductors connected to opposite terminals of a first coil near said loop antenna for voltage stepdown between said loop antenna and said first coil and having its terminals connected to opposite terminals of a second coil coupled to said 0011 in each of said input circuits, for the transfer of energy from said loop antenna to said input circuit, and means for selectively connecting one of said tunable input circuits to said unit for the transfer of signals from said loop over said link circuit to said unit.

5. In combination, a radio receiver having an input circuit, a short wave loop antenna arranged to be mounted remotely from said unit, a base structure carrying said loop, variable capacitance means proximate to said loop for tuning it to any selected one of a group of predetermined resonant frequencies, an untuned coil mounted on said base and coupled to said loop for substantial voltage stepdown from said loop to said untuned coil, means comprising a low impedance network for transferring a voltage induced in said coil to the input circuit of said receiver, and means for tuning said input circuit to the said having such a number of turns so that it serves to produce such substantial voltage stepdown and serves to match the impedance of the resulting tuned loop antenna with the impedance of such transferring means.

6. In combination, a receiver having an input circuit, a short wave loop antenna comprising a loop, a base structure carrying said loop, mounting means for said base whereby the loop may be located in desired positions, hinge means connecting said base to said mounting means whereby said loop may be oriented for best reception, variable capacitance means proximate to said loop whereby it may be tuned to a predetermined resonant frequency, a coil coupled to'said loop and mounted on said base, means for transferring a voltage induced in said coil from said loop to the input circuit of said receiver, and means for tuning said input circuit'to the same frequency as said predetermined resonant frequency.

7. In combination, a radio receiver having an input circuit, a short wave antenna comprising a loop, a base structure arranged to be placed remotely from said receiver and carrying said loop, a plurality of capacitors carried by said base, switching means for cutting individual capacitors into circuit with said loop whereby the same is tuned to any one of a plurality of predetermined resonant frequencies, a low impedance coil coupled to said loop for substantial voltage stepdown from said loop to said coil, said coil being mounted on said base, means for transferring a voltage induced in said cell from said loop to the input circuit of said receiver, and

means for tuning said input circuit to the same frequency. as said predetermined frequencies.

8. In combination, a portable radio receiver unit having an input circuit, means for tuning said input circuit to a frequency desirable for operation of said radio unit, a short wave loop antenna arranged to be mounted remotely relative to said unit, variable capacitance means arranged to tune said loop to a predetermined resonant frequency in a band of frequencies, and an untuned low impedance link circuit coupled to said-loop and coupled to said input circuit of the unit for the transfer of radio ener y selectively received in said loop to said unit.

, 9. In combination, a radio receiver-having an input circuit, :means for tuning said input circuit to a frequency desirable for operation of said receiver, a loop antenna arranged to be mounted in remote relation thereto, an untuned low impedance link circuit coupled to said antenna for substantial voltage stepdown from said loop to said link circuit, said link circuit being coupled to said input circuit and extending between said loop and radio receiver to communicate signals from said antenna to said receiver, and means proximate to said loop antenna for changing its resonant frequency to the first mentioned frequency.

10. In combination, a radio receiver having an input circuit, a pair of loop antennas, mount- .ing means -whereby said antennas may be mounted in alignment with a suitable dielectric surface, means pivotally connecting. said loop antennas to said mounting means whereby said loop antennas may be oriented in the most advantageous direction for signal reception, tuning means proximate .to one of said loop antennas whereby the same is adapted for the reception of a plurality of bands, a first coil coupled to said one loop antenna for substantial voltage stepdown from said last one loop antenna to said first coil, a second coil coupled to said input circuit, a pair of conductors extending between and connecting said first and second coils, said first coil and second coil and conductors comprising a link circuit, conductors connecting the other loop antenna to the input circuit of the receiver, cable means including all of said conductors, and switching means on the receiver for rendering each of said loop antennas alternatively effective to transfer signals to said receiver.

11. In combination, a radio receiver having an input circuit, a pair of loop antennas, mounting means whereby said antennas may be mounted in alignment with a suitable dielectric surface, means pivotally connecting said loop antennas to said mounting means whereby said loop antennas may be oriented in the most advantageous direction for signal reception, tuning means proximate to one of said loop antennas whereby the same is adapted for the reception of a plurality of broadcast bands, a first coil coupled to said one loop antenna for substantial voltage stepdown from said one antenna to said coiL-a' second coil coupled to said input circuit, a pair of conductors extending between and connecting said first and second coils in a series circuit, said series circuit comprising an untuned low impedance link circuit, conductors between the other loop antenna and input circuit of the receiver, cable means including said first and last mentioned conductors, switching means on the receiver for rendering each of said loop antennas alternatively effective to transfer signal energy to said receiver, said switching means including and selecting means for adapting the receiver or the reception of signals in any of a plurality of said bands.

12. In combination, a radio receiver having an input circuit and a housing, a pair of loop antennas, mounting means whereby said antennas may be mounted in alignment with a suitable dielectric surface, means pivotally connecting said loop antennas to said moimting means whereby said loop antennas may be oriented in the most advantageous direction I 1' signal reception, tuning means proximate to one of said loop antennas for tuning it at a predetermined resonant frequency for the reception of signals in a pluralitybf bands, a first coil coupled to said ne loop antenna for substantial voltage stepdown, a second coil coupled to said input circuit, conductors extending between and connecting said first and second coils in a series circuit, said first coil, second coil and conductors forming an untuned low impedance link circuit, at least one additional conductor extending between and connecting the other loop antenna to the input circuit of the receiver, cable means including all of said conductors and extending from said loop antennas to the receiver, a telescopic antenna,.said telescopic antenna being of such size with respect to said housing and arranged so that said antenna may be moved from a position substantially within said housing to a position where said antenna extends substantially entirely outside of said housing, switching means for alternatively connecting said other loop antenna and said telescopic antenna to said input circuit, an operating member for said switching means positioned in the path of movement of said telescopic antenna such that movement of said telescopic antenna between said position substantially within said housing and said podtion substantially outside of said housing results in alternatively connecting said other loop and said telescopic antenna to said input circuit, and switching means on the receiver for rendering each of said loop antennas alternatively effective to transfer signals therefrom to said input circuit.

13. In combination with an antenna for the reception of radiated energy, a receiver arranged to be energized by such energy and located at a substantial distance from said antenna, a tuned input circuit for the receiver, said antenna being tuned to the same frequency as said input circuit a low impedance link circuit extending between said antenna and receiver and including means at its ends for coupling said antenna to said link circuit and for coupling said link circuit to said input circuit of the receiver, said coupling means comprising means for reducing the voltage of said energy passing from said antenna to said link circuit and for increasing the voltage of said energy from said link circuit to the input circuit of said receiver.

14. In combination, radio apparatus, a housing for the radio apparatus, said radio apparatus including metal parts, a first antenna, a second antenna, means within said housing for movably mounting said first antenna with respect to said housing, said first antenna being of such size with respect to said housing and arranged so that said first antenna may be moved from a position substantially within said housing wherein said metal parts impair the eifectiveness of said first antenna to a position substantially entirely outside of said housing wherein said metal parts in fiuence in small degree the effectiveness of said first antenna, and switching means for rendering said first antenna and said second antenna alternatively effective for the passage of signals between said antennas and said apparatus, said switching means including a member arranged to move with said first antenna during at least a portion of the movement of said first antenna between said position within said housing and said position outside of said housing, said memher being arranged to disconnect said second antenna from said apparatus and to'connect said first antenna to said apparatus in response to movement of said first antenna to said outside position, the resulting connections being reversed upon movement oi said first antenna to said position within said housing.

15. In combination, radio apparatus including an energy transferring circuit a houisng for said apparatus, said radio apparatus including metal parts, an antenna movable from a position within said housing wherein said metal parts impair the effectiveness of said antenna to a position substantially outside of said housing wherein said metal parts influence in small degree the eiiectiveness of said antenna, and means including an operating member positioned in the path of movement of said antenna operated in response to movement of said antenna from said position within said housing to a position outside of said housing for electrically connecting said antenna to said circuit for the transfer of radio energy between said radio apparatus and antenna.

16. In combination, a radio apparatus, a housing for said radio apparatus, said radio apparatus including metal parts, a first antenna, a second antenna. means for movably mounting said first antenna with respect to said housing,

40 said first antenna being of such size with respect to said housing and arranged so that said first antenna may be moved from a first position substantially within said housing wherein said metal parts impair the efiectiveness of said first antenna to a second position substantially entirely outside of said housing wherein said metal parts influence in small degree the eflectiveness of said first antenna, and means including an operating member positioned in the path of movement of said first antenna operated in response to movement of said first antenna between said position within said housing to said position substantially entirely outside of said housing for alternatively connecting electrically said antennas to said apparatus for the passage of signals therebetween. 7

17. In combination, radio apparatus including a radio energy transferring circuit, said apparatus including metal parts, a first antenna movable from a position relatively near said apparatus wherein the eil'ectiveness of said antenna is impaired by said metal parts to a position more remote from said apparatus wherein said metal parts influence in small degree the efiectiveness of said antenna, a second antenna, and means responsive to movement of said first antenna from said position relatively near said apparatus to said more remote position for electrically disconnecting said second antenna from said energy transferring circuit and for electrically connecting said first antenna to said energy transferring circuit for the transfer of radio energy between said radio apparatus and first antenna, said disconnecting and connecting means including a member arranged to move with said first antenna during at least a portion of the movement of said first antenna between said positions, said member being arranged to move to open a circuit between said second antenna and said energy transferring circuit in response to said move-. ment and to close a circuit between said first antenna and said energy transferring circuit in response to said movement.

18. In combination, a radio receiver having a housing, said receiver including metal parts, a telescopic rod antenna mounted on said receiver for transferring signals thereto and arranged to extend substantially within said housing when the antenna is telescoped wherein said metal parts impair the effectiveness of said antenna and to extend substantially outside of said housing when the antenna is extended in which position said metal parts influence in small degree the effectiveness of said antenna, a second antenna for transferring signals to the receiver, switching means including an operating member positioned in the path of telescoping movement of the first mentioned antenna operated in response to movement of said first mentioned antenna from its telescoped position within said housing to its extended position outside of said housing for rendering said first mentioned and second antennas alternatively effective for the passage of signals between said antennas and receiver.

19. In combination, a radio receiver, said receiver including metal parts, a telescopic antenna mounted on said receiver for transferring signals thereto and arranged to be positioned in close proximity to said receiver when the antenna is telescoped in which position said metal parts impair the effectiveness of said antenna and to extend a substantial distance away from the receiver when the antenna is extended in which position said metal parts influence in small degree the effectiveness of said antenna, a loop antenna for transferring signals to the receiver, and switching means for rendering said first and second antennas alternatively effective for the passage of signals between the antennas and receiver, said switching means including a member arranged to move with said first mentioned antenna during at least a portion of the movement of the first mentioned antenna from its position close to said receiver to its position a substantial distance from said receiver, said member being arranged to move to disconnect said loop antenna from said receiver and to connect said first mentioned antenna to said receiver in response to saidmovemen-t.

20. In combination, radio apparatus, a housing for said apparatus, said apparatus including metal parts, an antenna, means within said housing for movably mounting said antenna with respect to said housing, said antenna being of such size with respect to said housing and arranged so that said antenna may be moved from a position substantially within said housing wherein said metal parts impair the effectiveness. of said antenna to a position where said antenna extends substantially entirely outside of said housing wherein said metal parts influence in small degree the effectiveness of said antenna, and means including an operating member positioned in the path of movement of said antenna responsive to movement of said antenna from said position substantially within said housing tosaid position entirely outside of said housing for operatively connecting electrically said antenna to said apparatus for the passage of signals therebetween,

21. In combination, radio apparatus, a housing for said radio apparatus, said apparatus including metal parts, an antenna movable from a position within said housing wherein said metal parts impair the efiectiveness'of said antenna to a position outside of said housing wherein said metal parts influence in small degree the eiiectiveness of said antenna, and means including an operating member positioned in the path of movement of said antenna responsive to movement of said antenna from said position within said housing to said position outside of said housing for electrically connecting said antenna to the apparatus for the passage of signals therebetween.

22. In combination, radio apparatus, a housing for said apparatus, a telescopic rod antenna for the reception of signals and movable from a telescoped position within said housing in close proximity to said apparatus to an extended position outside of said housing removed from said apparatus, said apparatus having metal parts which materially influence a function of the antenna when said antenna is positioned within said housing and in proximity to said apparatus, and means for connecting electrically said antenna to the apparatus for the passage of signals therebetween, said connecting means including a member arranged to move with said antenna during at least a portion of the movement of said antenna between its telescoped and extended positions, said member being arranged to move to close a circuit between said antenna and said apparatus in response to said movement.

23. In combination, radio apparatus normally disposed near the earths surface, a rod antenna attached mechanically to said apparatus and movable from a vertical position with respect to the earth's surface where said antenna is highly effective to pass signals to a position where said rod antenna extends substantially parallel to the earths surface, and means for operatively connectmg electrically said antenna to said apparatus for the passage of signals therebetween, said connecting means including a member arranged to move with said antenna during at least a portion of the movement of said antenna from said horizontal position to said vertical position, said member being arranged to move to close a circuit between said antenna and said apparatus in response to said movement.

24. In combination, radio apparatus including a radio energy transferring circuit, a first antenna movable with respect to said apparatus, a second antenna, and switching means for alternately connecting said first antenna and second antenna electrically with said radio energy transferring circuit for the alternate transfer of radio energy between said antennas and said apparatus, said switching means including a member arranged to move with said first antenna during at least a portion of the movement of said first antenna with respect to said apparatus, said member being arranged to move to connect said circuit to one of said antenna and disconnect said circuit from the other antenna in response to said movement.

25. In combination, means for receiving radio frequency energy, said means having a high impedance input circuit, a loop antenna winding spaced a substantial distance from said input circuit, a low impedance untuned link circuit extending between said input circuit and antenna winding and arranged to transfer radio frequency energy therebetween, said link circuit including a coil, means mounting said antenna winding and link circuit coil in close proximity to each other such that said antenna winding and link circuit coil comprise elements of a transformer, means for tuning said antenna winding to a frequency of signals desirable for operation of said radio receiving means, means for tuning said input circuit to the same frequency at which said antenna winding is tuned, and means for matching the impedance of the resulting tuned antenna winding to the low impedance of said link circuit, and means for matching the high impedance of said input circuit in said radio receiving means to the low impedance of said link circuit whereby radio energy is efficiently transferred between said antenna winding and link circuit and input circuit and variations of stray capacity of such link circuit produce no substantial effect on the transfer of such radio energy.

26. In combination, a radio receiver having an input circuit, a pair of loop antennas for the reception of radio signals, said antennas being arranged to be mounted remotely relative to the receiver, tuning means proximate to one of said antennas for tuning it to a predetermined resonant frequency, means for tuning said input circuit to a frequency equal to said predetermined frequency, means including conductors for coupling said one antenna to the input circuit of said receiver, means including at least one other conductor for coupling the other antenna to the input circuit of said receiver, flexible cable means including said conductors extending between said antennas and receiver, switching means on the receiver for rendering alternatively effective said one and the other antenna to transfer signals therefrom to said input circuit, said switching means including band selecting means for adapting the receiver for the reception of signals in any of a plurality of broadcast bands.

27. In combination, means for translating radio frequency energy, said means having an energy transferring circuit, a loop antenna spaced 9, substantial distance from said energy transferring circuit, means for tuning said antenna to a frequency desirable for the transmission of energy to said translating means, a low impedance untuned link circuit extending between said energy transferring circuit and said antenna and arranged to transfer radio frequency energy therebetween, means for tuning said transferring circuit to said desirable frequency, whereby radio energy is efficiently transferred between said antenna and link circuit and variations of stray capacity of said link circuit produce no substantial effect on transfer of such radio energy, a. low capacity antenna arranged to be connected to said energy transferring circuit, and switching means for alternatively connecting said antennas to said energy transferring circuit for the transfer of energy therebetween.

28. In combination, means for translating radio frequency energy, said means having an energy transferring circuit, a loop antenna spaced a substantial distance from said energy transferring circuit, means proximate to said antenna for tuning it to predetermined frequencies, a low impedance untuned link circuit extending between said energy transferring circuit and said antenna and arranged to transfer radio frequency energy therebetween, means for tuning said transferring circuit to frequencies equal to said predetermined frequencies, whereby radio energy is effectively transferred between said antenna and link circuit and variations of stray capacity of said link circuit produce no substantial effect on transfer of such radio energy, a movable low capacity antenna arranged to be connected to said energy transferring circuit, and means responsive to movement of said last antenna for alternatively connecting said antennas to said energy transferring circuit for the transfer of energy therebetween.

29. In combination, a radio receiver having an input circuit, a pair of antennas operable for the reception of radio signals in different frequency bands and being arranged to be mounted remotely relative to the receiver, means proximate to one of said antennas for tuning it to predetermined frequencies, means for tuning said input circuit to frequencies equal to said predetermined frequencies, means for coupling said antennas to the input circuit for the transfer of radio frequency energy in diflerent frequency bands to said input circuit, and means on the receiver for rendering each of said antennas alternatively effective to transfer radio frequency energy in different frequency bands to said receiver.

30. In combination, a radio receiver having an input circuit, a first and a second antenna operable for the reception of signals in different frequency bands, means proximate to said first antenna for tuning said first antenna to predetermined frequencies, said input circuit including a plurality of tuned circuits tunable to frequencies equal to said predetermined frequencies and arranged to be selectively coupled to said first antenna for the selective reception of signals in a plurality of frequency bands, switching means for selectively coupling one of said tuned circuits to said first antenna, means for coupling said second antenna to the input circuit of the receiver, and means responsive to operation of said switching means for uncoupling said first antenna from said input circuit.

31. In combination, a radio receiver having an input circuit, a first antenna and a second antenna arranged for the reception of radio signals in diflerent frequency bands, means for coupling said first antenna to said input circuit for the transfer of radio energy therebetween, means for coupling said second antenna to said input circuit for the transfer of energy therebetween, said last mentioned means including one of a plurality of tuned circuits tuned to predetermined frequencies for the selective transfer of signals between said second antenna and input circuit in any one of a plurality of frequency bands, means for tuning said second antenna to frequencies equal to said predetermined frequencies, means for selectively connecting one of said plurality of tuned circuits in operative relationship for .the selective transfer of signals between said second antenna and input circuit, and means responsive to actuation of said connecting means for uncoupling said first antenna from said input circuit.

32. In combination, an antenna, means proximate to said antenna for tuning the same to a single frequency within a range of frequencies, radio receiving apparatus, an input ,circuit for said radio receiving apparatus located remotely relative to said antenna, means for tuning said input circuit to a single frequency equal to the .first mentioned frequency, and a low impedance circuit coupling the resulting tuned antenna to the resulting tuned input circuit, the overall cou pling between the antenna and input circuit being of small degree such that efilcient energy transfer consistent with high selectivity and image ratio results.

33. In combination, a radio receiver, said receiver having a plurality of input circuits each tunable to the frequency of signals in a different range, means for connecting any selected one of said tunable input circuits to said receiver, means for tuning the selected circuit to any desired signal frequency within its range, a loop antenna arranged to be mounted remotely from said receiver, antenna tuning means proximate to the loop comprising discontinuous means for tuning the loop to any selected one of a plurality of frequencies each in a different one of said ranges and continuous means for tuning the loop to any signal frequency within the range for which the discontinuous means has been set, and means for coupling said antenna to the selected input circuit, said coupling means comprising a line having a coil at one end coupled to said loop antenna for substantial voltage stepdown from antenna to coil, means to match the impedance of said loop antenna to the impedance of the line, and means to match the line impedance to the impedance of the selected input circuit, said coupling means having a low characteristic impedance, a low shunt capacity, and providing a small degree of coupling between said antenna and input circuit.

34. In combination, radio receiving apparatus having an input circuit, means for adjustably tuning said input circuit, a loop antenna, means proximate to said antenna for adjustably tuning said antenna to a frequency corresponding to the frequency to which the input circuit is tuned, means for coupling said antenna to said input circuit, said coupling means comprising a.long flexible line having a coil at one end-coupled to said loop and arranged for substantial voltage stepdown from said loop to said coil, the overall coupling between said loop and said input circuit being of small degree, and means for quickly attachably and detachably supporting said antenna at a point removed from said receiving apparatus.

35. In combination, a radio receiver having an input circuit, means for adjustably tuning said tuned, and means for coupling said antenna to the selected input circuit, said coupling means comprising a line having a coil at one end coupled to said loop antenna for substantial voltage stepdown from antenna -to coil, said coupling means having a low characteristic impedance, a low shunt capacity, and a low overall coemcient of coupling.

' 37. In combination, a radio receiver, said receiver having a plurality of input circuits tunable to the frequency of signals in any one of a pin-- of frequencies each in a different one of said input circuit to a frequency desirable for operation of said receiver, a loop antenna arranged to be mounted in remote relation thereto, a line having a low characteristic impedance and a low shunt capacity, means for coupling in small degree said antenna to said line for substantial voltage stepdown from said antenna to said line, and means for coupling in small degree said line to said input circuit, said line extending between said antenna and input circuit to communicate signals from said antenna to said input circuit, and means proximate to said loop antenna for tuning it to the first mentioned frequency.

36. In combination, a radio receiver, said receiver having a plurality of input circuits tunableto the frequency of signals in any one of a. plurality of bands in a relatively large frequency spectrum, means for connecting any selected one of said tunable circuits to said receiver, means for tuning the selected circuit to any signal frequency within the selected band, a loop antenna ceiver, antenna tuning means proximate to this loop comprising discontinuous means for tuning the loop'to any selected one of a plurality of frequencies each in a different one of said bands, and continuous means for tuning the loop to any signal frequency within the band corresponding to the frequency to which said input circuit is arranged to be mounted remotely from said rebands and continuous means for tuning the loop to any signal frequency within the band corresponding to the frequency to which said input circuit is tuned, and means for coupling said antenna to theselected input circuit, said coupling means having a low characteristic impedance and a low shunt capacity and a low overall coefficient of coupling and comprising a line having a coil at one end coupled to said loop antenna, said coupling means being arranged to maintain the voltage therein substantially lower than the voltage in either said antenna or the selected input circult, means to improve the impedance match between said antenna and said line and between said line and said input circuit, and means for quickly attachably and detachably supporting said antenna at a point removed from said receiver. v

38. In combination, a. radio receiver having an input circuit, means for tuning said input circuit to any desired frequency within a range of frequencies, a first antenna, means proximate to said antenna for tuning it to the same frequency as said input circuit, said first antenna being movable to a position removed from said input circuit, means for coupling said'antenna to said input circuit, said coupling means having a low characteristic impedance and being arranged to provide overall coupling between said antenna and said input circuit of such small degree that etllcient energy transfer consistent with high selectivity results; a second antenna, and means for connecting said second antenna with said input circuit and disconnecting said coupling means therefrom and alternatively for disconnecting said second antenna from said input circuit and connecting said coupling means thereto.

39. In combination, radio receiving apparatus having an input circuit, means for adjustably tuning said input circuit to any desired frequency within the short wave range, a loop antenna, means proximate to said antenna for adjustably tuning said antenna to a frequency corresponding to said desired frequency, and long flexible means for coupling said antenna to said input circuit, the overall coefiicient of coupling between said antenna and said input circuit lying in a range of medium to loose coupling, said coupling means having a low characteristic impedance and a low shunt capacity.

40. In combination, a radio receiver having an input circuit, means for tuning aid input circuit to any desired frequency within a range of frequencies, a first antenna, means proximate to said antenna for tuning it to the same frequency as said input circuit, said first antenna being movable to a position removed from said input circuit, means for coupling said antenna to said input circuit, said coupling means having a low characteristic impedance and being arranged to provide overall coupling between said antenna and said input circuit of such small degree that efficient energy transfer consistent with high selectivity results, a second antenna, and means responsive to movement of one of said antennas with respect to said receiver for connecting said second antenna with said input circuit and disconnecting said coupling means therefrom and alternatively for disconnecting said second antenna from said input circuit and connecting said coupling means thereto.

41. In combination, an antenna, means proximate to said antenna for adiustably tuning the antenna to any desired frequency, radio receiving apparatus, an input circuit for said radio receiving apparatus, means for adjustably tuning said input circuit to a frequency equal to said desired frequency, and a flexible line having a low characteristic impedance and a low shunt capacity for coupling said antenna to said input circuit, the overall coupling between said antenna and input circuit being of small degree, means for supporting said antenna and said line on said receiving apparatus, said line being of sufficient length that when coupled between said antenna and input circuit, the antenna may be located at a remote point with respect to the input circuit, and means for quickly attachably and detachably supporting said antenna at such a remote point.

42. In combination, means for receiving radio frequency energy, said means having a high impedance input circuit, a loop antenna winding arranged to be placed a substantial distance from said energy receiving means. a line having a low asvaees characteristic impedance and a low shunt capacity extending between said energy receiving means and antenna winding and arranged to transfer energy therebetwecn, said line including a coil, means mounting said antenna winding and coil in close proximity to each other such that said antenna winding and coil comprise elements of a transformer, means variable to tune said antenna winding to a frequency of signals desirable for operation of said receiving means, means variable to tune said energy receiving means to the same frequency as the antenna winding is tuned, means for matching the high impedance of the tuned antenna winding to the low impedance of said line, and means for matching the high impedance of said energy receiving means to the low impedance of said line, said line being coupled to said antenna and said receiving means in small degree.

43. In combination, a radio receiver, said receiver having a plurality of input circuits tunable to the frequency of signals in any one of a plurality of bands in a relatively large frequency spectrum, means for connecting any selected one of said tunable input circuits to said receiver, means for tuning the selected circuit to any signal frequency within the selected band, a loop antenna arranged to be mounted remotely from said receiver, antenna tuning means proximate to the loop comprising discontinuous means for tuning the loop to any selected one of a plurality of frequencies each in a different one of said bands and continuous means for tuning the loop to any signal frequency within the band corresponding to the frequency to which said input circuit is tuned, and means for coupling said antenna to the selected input circuit, said coupling means having a low characteristic impedance, a low shunt capacity, and a low overall coefficient of pling.

GEORGE O. BTRIK'ER.

Images