US2571165A - Radio wave receiving system - Google Patents

Description

Oct. 16, 1951 R RlNES 2,571,165

RADIO WAVE RECEIVING SYSTEM Original Filed Feb. 18, 1946 2 Sheets-Sheet l @y MMM oct. 16, 1951 R, H, RlNES 2,571,165

RADIO WAVE RECEIVING SYSTEM Original Filed Feb. 18, 1946 2 Sheets-Sheet 2 o v Mg. Iz

v as PULSE E11/cantor.' 05527' H Z//VLS warn fr Patented Oct. 16, 1951 UNITED STATES PATENT OFFICE 1948, Serial No. 25,242

19 Claims.

The present invention relates to electric systems, and more particularly to radio-receiving systems that, while having more general elds of usefulness, are especially adapted for use in television. The present application is filed in'response to a requirement for division in application, Serial No. 648,482, filed February 18, 1946.

An object of the invention is to provide a new and improved radio-receiving system.

A further object is to provide a new and improved bridge circuit.

Another object is to provide a novel bridge circuit, employing electrets that are adapted to receive radio waves.

Other and further objects will be explained hereinafter and will be more particularly pointed out in the appended claims.

The invention will now be more fully explained in connection with the accompanying drawings, in which Fig. 1 is a diagrammatic view of circuits and apparatus arranged for radio-location purposes; Fig. 2 is a view of a modification; Fig. 3 is a diagram showing an airplane object from which radio waves are reected and scattered to the receiving system of Fig. 1; and Fig. 4 is a view of the preferred bridge-circuit radio-receiv ing system of the present application.

An electromagnetic-wave generator 4 is shown exciting a dipole 2 to produce ultra-high-frequency pulsed-radio energy, say, of 3 or 1.5 centimeters wavelength. A continuous-wave or any other type of modulated-wave generator may be employed, but pulsed energy, at present, has the advantage of economical and easy high-power ultra-high-frequency generation.

The waves emitted by the dipole 2 may be directed by a reflector 3 upon a parabolic reflector 6. The parabolic reflector 6 is shown directing the waves toward an object, say, an airplane 8, from which they are reected and scattered toward a receiving station.

At the receiving station, the radio waves thus reflected and scattered from the object 8 may be focused by an electromagnetic dielectric lens 6. such as polystyrene, upon a bank or array 1 comprising a plurality of normally ineiective radio-receiving pick-up unit antenna elements. The dielectric lens may be replaced by any other type of well-known lens, mirror or other directive system for focusing the electromagnetic energy scattered and reflected from the object 8 on the bank or array 'I of pick-up elements.

The pick-up elements of the bank or array 'I are shown arranged in the form of rows and columns, in the proximity of the focal plane of the Divided and this application May 5,

lens 5. The rst or uppermost row of the bank is illustrated as comprising the sections I0, I2, I4, I6, etc., shown as equally spaced horizontally. The second row from the top is shown comprising the sections I8, 20, 22, etc. The third or nextlower row is shown comprising the sections 24, 26, etc., and so on for the remaining rows of pickup elements. Though only a small number of pick-up units is shown in each row, this is merely for illustrative purposes, in order not to confuse the disclosure. It will be understood that, in practice, a large number of pick-up units will be employed in each row, say, 180.

The sections I0, I8, 24, etc., are arranged in the rst or right-hand column. The sections I2, 20, 26, etc., are disposed in the second column from the right. The sections I4, 22, etc., are disposed in the thirdrcolumn from the right, and so on. There may be as many columns as there are pick-up units in each row. Though each column is shown as comprising only a few pickup units, this is again in order not to complicate the drawings.

The pick-up units will, of course, all receive the reflected or scattered radio waves through the lens 5 simultaneously. There will be focused on each pick-up unit a radio-frequency voltage corresponding to the scattering from a corresponding view of the object 8. The pick-up elements will thus receive different field strengths of radio energy, corresponding to the amount of energy reilected or scattered from the various parts of the object 8 and converged upon the array 'I of pick-up elements by the lens 6. A radioenergy picture of the object 8, as will be presently explained, is thus recorded upon the array, specific elemental areas of which will correspond to specific elemental areas of the object 8. By

means of the present invention, this radio-energy' picture may be converted into a visible picture |23. According to the preferred embodiment of the invention, the visible picture |23 is caused to appear upon the fluorescent viewing screen |06 of a display cathode-ray oscilloscope tube 90. Though the tube 90, and also the hereinafterdescribed cathode-ray oscilloscope-like member 89, are shown operating on the electrostatic principle, magnetic deflection or a combination of magnetic and electrostatic forces may be employed. The invention provides a means for producing upon the screen |06 images corresponding to the radio-frequency energy received by the pick-up elements.

Provision is made for first renderingthe normally ineiiective pick-up units I0, I2. I4, I6, etc.,

oi' the r-st row successively 'ettectlve momentarily in the display circuits; for then rendering the pick-up units i8, 20, 22, etc.. oi.' the second row successively effective momentarily; `for then rendering the pick-up units 24. 26, etc.. of the third row successively effective momentarily; and

so on.

The pick-up units are shown arranged in an insulating disc 9 at the screen end oi. theoscilloscope-like member 66, and the pick-up umts may be constituted of electrets.

An electret is a permanently charged dielecunits may be positioned along the successive paths of the electron stream to enable the stream voltage with which the electrets become sensitric formed by filling the gap between two electrodes with, say, molten resin, carnauba wax, or beeswax. and subjecting the electrodes to high voltage. Byv allowing the .wax to cool during the application of the high voltage, a solidified per-y manently charged electric dipole is produced, having permanent piezo-electric properties. Investigations in this ileld are described, for example, by A. Gemant in the Philosophical Magazine. S. 7, vol. 20, No. 136, Suppl. November, 1935. pages 929 to 952.

As described by W. G. Cady in Piezoelectricity, McGraw-Hill, page 235, mixtures of the resin or carnauba wax with .other dielectric substances have produced long-lasting electrets. It will presently be explained that ii'V these dielectric bases are combined in the same manner with radio-absorbing-and-rectifying materials, `such as silicon or uranium oxide, the electrets can be particularly well adapted to the purposes of the present invention. .One of the electrodes of the electret, further, may serve to enhance the respouse to radio energy if. it is, for example, tuned to the radio waves, ii. it is one-quarter of a wavetized during their preparation. VThis alteration results from several factors, including heating or pyroelectric eects, the negative temperature coemcients of resistance and the piezo-electric properties of the electrets. Silicon and uraniumoxide detectors are known to absorb radio-iremon strip 6| connected to the strip 4l. Similarly, i

' the third row is shown composed of charged dielectrics 24, 26, etc., with top electrodes |24, |26,

etc., and a common terminal strip 61 connected to the other common strips 43 and 6|. The strips 46, 5| and 61 are shown connected by a conductor 18 to a grounded impedance 66 in the input circuit of an ampliiler 16.

The cathode-ray-oscilloscope-like member 66 is shown provided with a cathode 66, a controlgrid electrode 93 and an anode .61. emitted from the cathode 66 will become enabled, in response to proper stimulation oi the grid 62, to pass by the grid 96, to the anode 61 of the member 86. The electrons will continue to travel in a stream from the anode 61, between a pair oi.' vertically disposed deflector plates 66 and |0l, of which the plate 66 is shown grounded. and between a pair of horizontally disposed deflector plates |06 and |05, oi which the plate |06 is shown grounded, to impinge nally on the disc 6 of the member 66. base, applied, asy hereinafter more fully explained, to the vertically disposed deilector plates 96 and |0|, will cause the electron stream from the cathode 66 to become deflected horizontally, and a vertical-sweep-time base, applied to the horizontally disposed deilector plates |06 and |06, will cause the electron stream to become deflected vertically. 'Ihe rows of electret pick-up A horizontal-sweep-time- Electrons quencyl energy and to exhibit negative temperature coemcients of resistance.

'Ihe energy absorbed by each electret is a` these tuned electrodes, the detecting electrets and the grounded conductor 10. The rectiilcation is produced by the detecting dielectric disposedbetween the electret electrodes. The variation ot potential and charge along the bank or electrets is th'us a measure ofthe radio-irequency energy impingedon the array by the lens 6.

The resistance of the silicon or uranium oxide, as well as of the wax of the electret, since their temperature coeillcients are negative, changes with the intensityof ther vimpinging radio-irequency energy. A resistance, variation is thus produced along the bank o! electrets that is `representative of the radio-frequency energy .re-`

ceived by the respective electrets. y These three eilects involving the change oi' the lelectret charge upon the Iabsorption by the electrets oi the radio-frequency energy. the production oi' the .direct-current potentials as a result of the detection or rectification in `the abovementioned radio-receiving circuits, and the re'- sistance changes render the electrets extremely sensitive. A radio-energy image o! the object l becomes thus recorded upon the array oi electrets as charge, potential and resistance distributions. l

The bank oi electrets may be scanned' according to either of. two principles or according to al combination of the same. One principle involves` measuring' the variation in the electric charge and potential of the bank at the moment ,that the electron stream impingesupon the successively disposed electrets `to short-circuit them.'

' 'I'he other principle involves measuring in a Eachelectret will absorb and rectify the radiofrequency energy. Dependent upon the magnitude of this energy, it will change the resistance and the charge of the electret. This change will result both as a consequence oi the absorption and of the rectifying action by the electrets of the radio-frequency energy received by the electr-et electrodes. As the electron stream successively impinges upon the successively disposed electrets, during the scanning, it successively discharges them. This produces a corresponding change in the input voltage to the amplifier 18, indicative of the radio-frequency energy impinged on the respective electrodes.

The electron stream will instantaneously discharge each differently-charged and differentlypotentialed electret to give an indication in the load 58 and the amplifier 18, or it will give rise to a change-in the electron-beam current when it impinges upon the variously resistive electret elements, or there may be a combination of these effects.

The scanning of the electrets may obviously also operate on the principle of change in electron-beam current transmitted to the load 58 upon impinging on surfaces of various resistances. As the stream hits these electrets of dierent resistances, a change in beam current occurs, which manifests itself in the input circuit of the amplifier 18.

Mosaics of electrets for the member 88 may also take the form of Fig. 2, where electrets 8|, 84, 86, 88 are provided with front electrodes |8|, |84, |86, |88 exposed to the radio energy converged by the lens 5. The electrode strips |8|, |84, |86, |88 may be of length one-quarter of the wave-length of the radio waves and may be in the interior of the tube 88, facing the electron stream, and may be scannedby it. The electrodes 28|, 284, 286. 288 will be capacitively coupled t-o the front electrodes and will assume the homocharge of the electret. Thus, the electron stream will impinge on surfaces of different charge or potential. and the scanning will take place according to the principles previously described.

The electrets may be separated from adjacent electrets by dielectric material 206.

As the electron stream produced from the cathode 95, in response to appropriate horizontal-sweep-time-base voltages applied to the vertically disposed deflector plates 88 and |84 of the cathode-ray-tube-like member 89, travels across the pick-up elements in the disc 8, they will successively discharge into a grounded preferably linear amplier 18, by way of a conductor 18. If desired, the amplifier 19 may be replaced by a bank of linear amplifiers, one corresponding to each of the pick-up elements.

The output of the amplier 18 will obviously vary, at successive instants, in accordance with the radio-frequency energy received by the successive corresponding pick-up elements.

A pulse generator, which may, if desired, be the same pulse generator 4, may be employed to trigger a horizontal-time-base-sweep circuit 63 and a vertical-sweep circuit 68, according to conventional and well-known televisiontechnique. The pulse generator 4 may feed, through an attenuator and rectifier to an oscillator or any similar or equivalent television circuit. One such circuit is shown as a pulse-recurrence-frequency multiplier 65, for applying many pulses corresponding to each radio-frequency pulse for the period between successive radio-pulses, to trigger the horizontal-sweep circuit 63. The horizontal-time-base sweep will thereby be produced between the vertically disposed deector plates 88 and |0l, occurring-as many times, say, between successive radio-frequency transmissions, as` there are rows of pick-up antennas. The pulse generator 4 may also feed, through the attenuator and rectifier I, 'to trigger the vertical-sweep circuitl 68, once corresponding to every radio-frequency transmission. One vertical sweep will then occur between the horizontally disposed plates |03, |05 during the periods between successive radio pulse transmissions. corresponding to as many horizontal sweeps as there are rows of antennas, causing each of the horizontal sweeps to appear at successively lower levels on the oscilloscope-sweep face.

I f the circuit comprises an oscillator, the oscillations may be employed to trigger the horizontal sweep. The period of the oscillations which, as previously explained, is much less than the duration of each radio pulse, corresponds to the time of sweep across one row of the pick-up units in the disc 9.

If, as previously mentioned, continuous-wave radio transmission is employed, the verticalsweep circuit 69 may be triggered to produce one vertical sweep corresponding to as many horizontal sweeps from the horizontal-sweep circuit 63 as there are rows of pick-up units.

Means is provided for producing upon the screen |06 of the display oscilloscope 80, images corresponding to the radio-frequency energy received by the corresponding pick-up mosaic antenna elements. The screen |06 is illuminated by an electron stream in the oscilloscope 80. This electron stream is synchronized to travel with the electron stream of the cathode-ray-like member 88. The horizontal-sweep circuit 63 is connected to the horizontal-deflector plate |00 of the oscilloscope by a conductor 61, and to the horizontal-deflector plate I0| of the oscilloscope-like member 88 by the conductor 61and a conductor |34. The vertical-sweep circuit 68 is connected to the vertical-deilector plate |02 of the oscilloscope 80 bya conductor 1|, and to the vertical-deector plate |03' of the oscilloscopelike member 89 by the conductor 1| and a conductor |46.

The amplifier 18 is connected, by conductors and 81, to the control-grid electrode 82 and the cathode 84 of the oscilloscope 90. The mosaic of electrets becomes thus successively connected, through the amplifier 19, to the control electrode 92. Electrons emitted from the cathode 84 will become enabled, in response to the action of the amplifier 18, to pass by the grid 92, to the anode 96 of the oscilloscope tube 90. The electrons will continue to travel in a stream from the anode 96, between the pair of vertically disposed oscilloscope deilector plates 98 and |00, of which the plate 88 is shown grounded, and between the pair of horizontally disposed oscilloscope deflector plates |02 and |04, of which the plate |34 is shown grounded, to impinge finally on the fluorescent viewing screen |06 of the osci loscone 8.1.

After each simultaneous horizontal sweep of both the oscilloscope 90, and the oscilloscope-like "member 88 has been completed. a successively larger voltage will be applied to the horizontally disposed deector plates |02, |04 and |03, |05, respectively, by the vertical-sweep circuit. After the last such horizontal sweep, the voltage between the horizontally disposed plates |02, |04 and |03, |05 will become restored to zero. The next horizontal sweep, therefore, will start again at the first or top row.

Successively disposed areas of the screen |06 of the oscilloscope 80 will therefore correspond to the similarly disposed mosaic-antenna sections armies might be any well-known bridge detector oi, say,I

the Wheatstone construction. A bridge circuit embodying an electret in an arm of the bridge provides for taking advantage of the betorede scribed sensitive properties of the electret in affecting the balance of the bridge. For the particular radio-wave-location purposes above menf tioned, i1 a plurality of electrets are connected, for example, in a direct-current series circuit, then the bank of electrets may serve as an extremely sensitive radio-detecting element oi a Wheatstone bridge, in which they may be balanced against fixed impedance elements 2I2, 2|! an'd 2li, as shown in Fig. 4. The short-circuiting or exploring oi' each successive electret by the electron stream, diagrammatically shown as snorting switches 205, 201, 200, in parallel with the electrets 204, 200, 200. would thus bemarkedly indicated in the ampliiler and fed to the control electrode 02 oi the display oscilloscope 00.

Although the invention has been described in connection with mosaic-antennas arranged in rows and columns, it will be understood that this is not essential. tor other arrangements are also possible. Antennas arranged along concentric circles covering the field, or a continuous spiral, will also serve, though the oscilloscope arrangement would. or course, be correspondingly modi-l iied. f

In the case of the concentric circles and the spiral, the antennas would be rendered effective in two-dimensional order, as in the case of the rows and columns before described. 'I'he antennasI disposed along one or the circles, for example, would `flrst be rendered effective. then those along the next circle, and so on.

Further modifications will occur to persons skilled in the art. and all such are considered to fall within the spirit and scope of the invention.

as deiined in the appended claims.

what is claimed is: 1. A bridge having a plurality of arms one of which, comprises electret means. and means for indicating variations in the bridge.

' V 2. A bridge having arms one oi which comprises a plurality oielectrets for receiving radio waves, and means for indicating variations in the balance of the bridge in response to radio waves 4. A bridge having four arms connected together to form two pairs of oppositely disposed vertices. one of the arms having electret means, an input circuit connected te one of the pairs lpregnated with a radio-wave-absorbing-sndof vertices. and an output circuit connected to the other pair of vertices.

5. A bridge having four arms connected together to form two pairs of oppositely disposed vertices, one oi.' the arms, having a plurality of series-connected electret elements, an input circuit connected to one o! the pairs of vertices,

Aarms oi" which are provided 8 and an output circuit connected te the other pair of vertices. 4

6. A bridge having four arms connected together to form two-pairs ot oppositely disposed vertices, one ot the arms comprising a plurality of electret elements. an input circuit connected v to one'of .the pairs of vertices, an output circuit. connected to the other pair lof vertices, and means for causing the successive electret elements to produce successive indications in the ouwut circuit.

1. A bridge having arms one of which contains a plurality of electrets for receiving radio waves, each electret comprising a dielectric base impregnated with a Vradio-wave absorbing-andrectitying material, and means for indicating variations in the balance of the bridge in response to radin waves received by the electrets.

8. A bridge having arms one of which contains a plurality oi electrets for receiving radio waves, each electret comprising wax impregnated with silicon, and means for indicating variations in the balance of the bridge in response to radio waves received by the electrets,

9. A bridge having arms one of which contains a plurality of electrets for receiving radio waves, each electret comprising a dielectric base imrectitying material, and the other arms of which contain ilxed electrical elements, and means ior indicating variations in the vbalance ot the bridge in response to radio waves received -by the electrets.'

10. A bridge having arms one o! which contains electret means for receiving radio waves com-` prising a dielectric base impregnated with a. radio-wave-absorbing-and-rectifying .material and provided with electrode means tuned to the i'requency of the radio waves, and means for indicating variations in the balance of the bridge in Iresponse tc radio waves received by the electret means. l

11. A multi-arm electrical bridge circuit one arm of which comprises electret means for receiving and rectifying radio waves and the other with axes eisen-ien. elements, and means for indicating variations in the balance o! theV bridge in response to radio waves received by the electret means.

12. A bridge having a plurality of arms one of which comprises a permanently charged element comprising permanently polarized dielectric base electret means. means for directing an electron stream towardthe electret means. and means for indicating variations in the bridge.

13. A bridge having four arms connected together to form two pairs of oppositely disposed vertices, one of the arms having means comprising a permanently polarized dielectric base, an input circuit connected to one of the pairs ot vertices. an output circuit connected to the other 4pair of vertices, and means for directing an electron stream toward the dielectric base.

14. A bridge having tour armslconnected together to form two pairs of oppositely disposed vertices, one of the arms'having an electric network comprisingv a plurality of .elements each comprising a 'permanently polarized dielectric base. an input circuit connected to one of the pairs of vertices. an output circuit connected to the other pair of vertices. and means for causing the successive elements te produce successive indications in the output circuit.

15. A bridge having arms one o! which contains an electric network comprising means for receiving radio waves comprising a permanently polarized dielectric base impregnated with a radiowave absorbing-and-rectifying material, and means for indicating variations in the balance of the bridge in response to radio waves received by the receiving means.

16. A bridge having arms one of which contains an electric network comprising means for receiving radio waves comprising permanently polarized wax impregnated with silicon. and means for indicating variations in the balance o! the bridge in response to radio waves received by the receiving means.

17. A bridge having arms one of which contains an electric network comprising a plurality of elements for receiving radio waves, each element comprising a permanently polarized dielectric base impregnated with a radio-wave-absorbingand-rectifying material, and the other arms of which contain fixed electrical elements. and means for indicating variations in the balance of the bridge in response to radio waves received by the elements.

18. A bridge having arms one of which contains means for receiving radio waves comprising a permanently polarized dielectric base impregnated with a radio-wave-absorbing-and-rectifying material and provided with electrode means tuned to the frequency of the radio waves, and means for indicating variations in the balance l0 of the bridge in response to radio waves received by the receiving means.

19. A bridge having four arms connected together to form two pairs of oppositely disposed vertices, one of the arms comprising a plurality of elements each comprising a permanently polarized dielectric base, an input circuit connected to one of the pairs of vertices. an output circuit connected to the other pair of vertices. and means for scanning the successive elements to produce successive indications in the output circuit.

ROBERT H. RIN'ES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,886,234 Meissner Nov. 1. 1932 2,155,509 Schroter Apr. 25, 1939 2,230,649 Mason Feb. 4, 1941 2,460,109 Southworth Jan. 25, 1949 2,485,863 Chandler Oct. 25, 1949 OTHER REFERENCES Review of Scientific Instruments, vol. II. February 1940, pages to '11.

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