US2028866A - Ultra short wave communication system - Google Patents

Description

Jan. 28, 1936.

C. W. HANSELL ULTRA SHORT WAVE COMMUNICATION SYSTEM Filed June 2, 1933. 2 Sheets-Sheet 1 u E 5 M Y f WH E mw. m EEQ/ o VC n www A R A L C Y B 2 Sheets-Sheet 2 28, 1936. Q w HANSELL ULTRA SHORT WAVE COMMUNICATION SYSTEM Filed June 2, 1953 Patented Jan. 28, 1936 ,e UNITED STATES PATENT oFFlcE ULTRA SHORT WAVE COMIWUNICATION SYSTEM Clarence W: Hansell, Port Jefferson,

N. Y., as-

signor to Radio Corporation of America, a corporation of Delaware Application June 2, 1933, Serial No. 673,974

, wavesb-y means'`V of a common oscillator and reector system.

A feature of the present invention is the reflecting system utilized which comprises two re-V flectors, one of a parabolic type and the other a 15. hemi-spherical rellector located in the focus of the; parabolic reflector and arranged4 to direct energy into said parabolic reflector. These reectors are arranged upon a pivoted support by means of which transmission and reception may. be carried out any desired direction.

A further feature is the means employed to prevent interaction between the transmitting and receiving circuits of the system.'

In brief, the invention comprises an ultra high frequency oscillator,l for example, a Barkhausen oscillation, the radiating elements ofV which are located at the center of a hemi-spherical reector and in the focus of and facing towards a parabolic reflector. This oscillator is arranged to produce radiation and, in practice, will ordinarily utilize the energyA feed lines as the oscillatory circuit on which standing waves are allowed to develop. For transmission purposes, the hemispherical reector catches all the radiation going r out in a more or less forward direction and sends it back towards the center of the oscillator system so that it will fall upon the parabolic Vreilector as` if it had come directly from the oscillator. By properly dimensioning the two rei ectors, all of the radiation is caught by the reflector system and reflected from the parabolic reflector in the desired direction. Thus there is no-leakage of energy due to radiation missing the reector and maximum directivity is obtained. 1t is proposed to modulate the output of the oscillator by varying the potential on its electrodes: in any suitable manner. The same` system may also be used for reception by causing any energy falling upon the rei:l flector tol be impressed` upon the oscillator circuits and thus give rise to a variation in the input electrode currents to the oscillator,

A more complete understanding of the invention may be had by referring to the following 55. detaileddescription which is accompanied by 10 claims. (c1. 25u-e) drawings, wherein Figure 1 illustrates a complete ultra short wave communication system for effecting simultaneous transmission and receptionat a single point in accordance with the principles of the present invention, and Figure 2 illustrates a modification thereof wherein there is utilized a Wheatstone bridge or hybrid coil arrangement for aiding in preventing interaction between the transmitter and receiver of the reflector system.

Referring to Figure 1 in more detail, there is shown, schematically, a Barkhausen oscillator l, the eiective radiating center of which is located at the center of a heini-spherical reflector 2 and in the focus of a parabolic reflector 3, both being pivotally mounted at 2li and 2| for movement in any desired direction. Hemi-spherical reflector 2 is arranged to direct energy received by it back toward the parabolic reflector 3 fromwhich radiation is reflected in the desired direction. A source of potential 4 is provided for supplying a relatively high positive potential to the grid of the Barkhausen oscillator, and a source of potential 5 acts to supply a small negative potential to the anode thereof. This anode may be eitheriat a negative potential, as shown, or else at a small positive or even at the same potential as the cathode. For tuning the tube leads., there is provided a group of bypass condensers 6 in which adjustable taps on each of the tube leads serve to join all the leads together for radio frequency currents, and still leave each lead of correct length for optimum oscillating conditions. The oscillations generated in the Barkhausen oscillator l are caused to exist as standing waves on portions of the leads extending from the electrodes of the oscillator l through the parabolic reector 3 to the sources o-f potential 4 and 5.

For modulating the oscillations, there is provided any suitable signal modulating means, such as a microphone 1, which is coupled to audio frequency transformer l0 through an amplier 8 over any suitable transmission line, such as a telephone line 9, the currents in the secondary of transformer I0 being arranged to vary the grid potential on the Barkhausen oscillator and thus also vary the strength of the oscillations, The variations in strength of the oscillations will be detected at a distant receiving station. If desired, both the grid and anodel potentials may be modulated in order to obtain amplitude modulation independent of frequency modulation or, in some cases, frequency modulation independent of amplitude modulation. One such U. S. Patent 1,938,749, granted December 12, 1933, to N. E. Lindenblad.

The system indicated may also be used for reception since any energy falling upon the parabolic reflector 3 and being impressed upon the oscillator circuits will give rise to a variation in input current to the oscillator by adding to and opposing the local oscillations. If the transmitter from which it is desired to receive a communication has its frequency made somewhat different than the oscillator shown in the drawings, then the electrode input current will vary periodically at a rate corresponding to the difference between the two frequencies and these variations will have an amplitude substantially proportional to the strength of the received radiation. Preferably, the beat between the carrier of the transmitter to be received and that of the oscillator shown in the gure should be at some frequency higher than audibility. It might, for example, be 1,000,000 cycles per second. By means of a tuned circuit I I inserted in series with the lead to the grid there can be selected this one million cycle beat, and the energy from this circuit may be coupled through an intermediate frequency receiver I3 to an ordinary loudspeaker or telephone receiver IZ for enabling the reception of the modulation of the distant transmitter. The system may be employed for receiving communications from any one of a number of distant transmitters operating near the same frequency by simply tuning the intermediate frequency receiver for the beat frequency between the distant transmitter and the local ultra short wave oscillator. Of course, if the distant transmitters are located in different directions the reflector must be turned on its pivot to selectively receive from the desired direction.

In the circuit shown, the intermediate frequency tuned circuit I I has negligible impedance for the audio input energy transmitted over line S and transformer I0, and. permits the modulation of the oscillator due to this audio energy without any impediment. Audio transformer I0 is designed to present a low impedance to the 1,000,000 cycle beat frequency, and the secondary winding thereof may, if desired, be shunted by a bypass condenser I5 which has relatively low reactance for the intermediate frequency. In the arrangement indicated it is possible that modulation of the oscillator for transmission purposes may cause some variation in the strength of the intermediate frequency impressed upon the intermediate frequency receiver I3, though, in general, there is a tendency for the intermediate frequency energy to be independent of the strength of the local oscillations over a considerable range. In any case its only effect is to make a speakers voice audible in his own receiver and this is not objectionable since it is the common condition in almost all telephone circuits.

If it is desired to prevent the audio input energy impressed by amplier S upon line 9 and transformer I0 from being reproduced through the intermediate frequency receiver I3, an arrangement such as is indicated in Figure 2 may be employed wherein a hybrid coil is used. This hybrid coil is in the nature of a Wheatstone bridge which permits combining outgoing and incoming energies into a single circuit without permitting the outgoing energy to return again to the transmitter via the receiver in a manner to set up spurious oscillations or singing.

In Figure 2 microphone 1 is shown connected in parallel with a telephone receiver I2 across the common telephone transmission line 9 which, in turn, is connected to the ends of two windings IS and. I1 of a hybrid coil 23. The opposite ends of the windings are connected to an impedance Z which simulates or matches the electrical constants of the telephone line. From the center of windings I6 and I1 connections are made to the input terminals of the transmitter amplier 8. A second winding or pair of windings I8 and IS on the hybrid'coil are connected to the output of the intermediate frequency receiver I3.

With the arrangement shown in Figure 2, when l the adjustments are correct, output energy from the receiver cannot enter the'transmitter, but half of the energy is transmitted over the wire line 9 to the operators receiver i2. The telephone transmitter currents are likewise prevented by the hybrid. coil 23 from entering the receiver output circuit, but this is not important inasmuch as the receiver is a unilateral device and cannot cause singing due to reversed energy transmission through it.

'Ihe foregoing invention is arranged to provide a highly efficient communication system Vat extremely low wave lengths of less than one meter with excellent power output and may be used for such purposes as communication between ships in a harbor, between ships of a fleet, for relatively short distance communication between individuals, between buildings, across streams, etc.; in fact, the invention may be used wherever the relative cheapness of a single system would be an advantage for both transmission and reception.

I claim:

1. An ultra short Wave communication system for the simultaneous transmission and reception of electromagnetic energy comprising a wave reflecting surface formed to approximate a paraboloid and a hemi-spherical reflector mounted in the focus of said reflecting surface and arranged to direct energy toward said surface, a Barkhausen oscillator comprising a cathode, anode and control, electrode mounted in the center of said hemispherical reflector, said control electrode being at a high positive potential with respect to said lanode and cathode, sources of potential for said electrodes, energy feed leads extending from said oscillator through said reflecting surface to said sources, signal modulating means coupled to the electrodes of said oscillator, and receiving apparatus also coupled to said electrodes.

2. An ultra short Wave communication system for the simultaneous transmission and reception of electromagnetic energy comprising a parabolic reflector and a heini-spherical reector mounted in the focus of said parabolic reflector and arranged to direct energy toward said parabolic reflector, a Barkhausen oscillator comprising a cathode, anode, and control electrode mounted in the center of said heini-spherical reector, said control electrode being at a high positive potential with respect to said anode and cathode, sources of potential for said electrodes, energy feed leads extending from said oscillator through said parabolic reector to said sources, signal modulating means coupled to the electrodes of said oscillator, receiving apparatus also coupled to said electrodes, and a Wheatstone bridge arrangement coupled to said energy feed leads for preventing undesirable reaction between said transmitter and receiver.

3. An ultra short wave communication system for the simultaneous transmission and reception of electromagnetic energy comprising a parabolic reflector and a hemi-spherical reflector mounted in the focus of said parabolic reflector and arranged to direct energy toward said parabolic reflector, an oscillator comprising a cathode, anode, and control electrode mounted in the center of said hemi-spherical reflector, said control electrode being at a high positive potential with respect to said anode and cathode, sources of potential for said electrodes, energy feed leads extending from said oscillator through said parabolic reflector to said sources, signal modulating means coupled to lthe electrodes of said oscillator, a parallel tuned circuit tuned to an intermediate frequency coupled to said oscillator, an intermediate frequency receiver connected to said parallel tuned circuit, an acoustic device, said intermediate frequency receiver being arranged to supply audio frequencies to said acoustic device. l

4. An ultra short wave communication system for the simultaneous transmission and reception of. electromagnetic energy comprising a parabolic reflector and a hemi-spherical reflector mounted in the focus of said parabolic reflector and arranged to direct energy toward said parabolic reilector, a Barkhausen oscillator comprising a cathode, anode, and control electrode mounted in the center of said henri-spherical reflector, said control electrode being at a high positive potential with respect to said anode and cathode, sources of potential for said electrodes, energy feed leads extending from said oscillator in a direction along Vthe `focal line of said parabolic reflector to said sources, signal modulating means coupled to the electrodes of said oscillator, and

receiving apparatus also coupled to` said electrodes.

5. An ultra short wave radio communication system for the simultaneous transmission and reception of Waves below one meter comprising a single oscillator for both transmission and reception, a reflector, said oscillator being at the focus of said reflector, and feed leads having standing waves thereon extending along the focal line of said reflector from the electrodes of said oscillator to energy supplymeans.

6. An ultra short wave radio Vcommunication system for the simultaneous transmission and .reception of waves below one meter having, in

combination, a parabolic reflector arrangement pivoted so as to be capable of `motion for directive action in any desired direction, and an oscillatory system extending along the focal line of said parabolic reflector comprising an electron discharge device oscillator and leads from said oscillator through said reflector, and means for producing standing waves on said leads.

7. An ultra short wave radio communication system for the simultaneous transmission and reception of waves below one meter having, in combination, a parabolic reflector and a hemi-spheriarranged to' direct energy toward said parabolic reflector, and an oscillatory system whose effective center is at the focus of both of said reflectors, said oscillatory system comprising a single electron discharge device having an anode, cathode, and control electrode, leads for said electrodes extending through said parabolic reflector to energy supply means for maintaining said control electrode at a positive potential relative to the cathode and anode, and signal modulating means in circuit with said electrodes whereby there are Vcaused to exist standing waves on said leads, said reflectors being pivotally mounted for directive action on the arc of a circle.

9.'An ultra short wave radio communication system for the simultaneous transmission and reception of waves having, in combination, a parabolic reflector and a heini-spherical reflector arranged to direct energy toward said parabolic reflector, and an oscillatory system whose effective center is at the focus of both of said reflectors and which extends along the focal line of said reflectors at least up to said parabolic reilector, a transmitter and a receiver in circuit with said oscillatory system, said receiver having means for selectively receiving the beat frequency between the oscillations generated by said oscillatory system and the received waves, and a balancing circuitV for preventing undesirable reaction between the transmitted and received modulation currents.

10. An ultra short wave communication system for the transmission and reception of electromagnetic energy below one meter comprising a parabolic reflector and a hemi-spherical reflector mounted in the focus of said parabolic reflector and arranged to direct energy towards said parabolic reflector, a radiating system at the focus of both said reflectors comprising a multi-electrode electron discharge device oscillator whose control electrode is at a high positive potential relative to its cathode, and feed leads having standing waves thereon extending from the electrodes of said device along the focal line of said reflector through said parabolic reflector to energy supply means, signal modulating means coupled to the electrodes of said oscillator and receiving apparatus also coupled toy said electrodes.

. CLARENCE W. HANSELL.

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