US2098756A - Directive wireless system - Google Patents

Description

Nov .9,1937. P, E'BANSK. Y 2,098,756.

DIRECTIVE WIRELESS SYSTEM Filed Nov. 2, 1934 s Sheets-Sheet 2 INVENTOR IOZEF PLEBANSKI ATTORNEY Nov. 9, 1937. J. PLEBANSKI 2,098,756

DIRECTIVE WIRELESS SYSTEM Filed Nov. 2, 1934 5 Sheets-Sheet 5 AMPLIFIER RF. AMPLIFIER PHASE 5H IFIER RECEIVER iNVENTOR JOSE? PLEBANSKI ATTORNEY Patented Nov. 9, 1937 UNETED STAl'Eg FATE 'i GFE DIRECTIVE WIRELESS SYSTEM Application November 2, 1934, Serial No. 751,228 In Poland November 4, 1933 13 Claims.

This invention relates to antenna systems and more particularly to directional receiving an tenna systems and has for its main object to provide means whereby the directive properties 5 of a receiving antenna system which is itself inherently directional may be substantially augmented.

A further object of the invention is to provide improved means whereby the direction of maximum sensitivity may easily and conveniently be controlled.

These objects are achieved, in carrying out the present invention, by the provision of what is V hereinafter referred to as directional reaction. 15 This so-called directional reaction, as will be shown later, increases the relative strength of signals arriving from the desired direction as compared with signals arriving from other directions in a manner which is analogous to that 29 in which signals of desired. frequency are increased in strength relatively to those of undesired frequency by ordinary reaction or regeneration in vacuum tube radio circuits.

A further object of my invention is the prevision of means and methods for varying the de gree of sharpness of the transmitting and/or receiving characteristic of a directive aerial system.

Another object of the invention is to provide a new directive system and method of operating 39 same by which a desired degree of sharpness or directivity is obtained with a substantially decreased amount of apparatus required and with an aerial system of substantially reduced size and extension as compared to directive aerial systems heretofore known in the art.

The invention has other objects and advantages in view which will appear hereinafter in a detailed description thereof in connection with the accompanying drawings in which I have shown several forms of embodiment of the invention.

In these drawings:

Figures 1 and 2 illustrate schematically elevation and plan views, respectively, of one em- 45 bocliment of an aerial system according to the invention.

Figures 3 and l show directive polar diagrams explanatory of the function and results of the system shown by Figs. 1 and 2.

50 figures 5 and 6 illustrate in elevation and plan views, respectively, a modification of an aerial system according to the invention.

Figures 7 and 8 represent vector diagrams explanatory of the function of the system accord- 55 ing to Figures 5 and 6.

Figure 9 shows a further directive aerial system of the type according to the invention, while Figures 10 to 13 represent descriptive polar diagrams explanatory of the function of and advantages obtained by the invention. 5"

Figures 16 and 1'? illustrate more clearly the 10 arrangement of a system according to the invention embodying superheterodyne amplifiers and phase shifting means for adjusting the di-' rectional characteristic.

Similar reference characters identify similar parts throughout the different views of the drawings.

Referring to Figures 1 and 2 which illustrate schematically elevation and plan views, respectively, of one embodiment of the invention, A1, 20 A2 An represent a plurality of aerials such as straight wire aerials as shown, forming together with reflectors R1, R2 Rn, a directive an tenna system of well known design. In order to obtain directional reaction in accordance with the invention, a second directive antenna system HA1, HA2 RAH, together with reflectors RRl, RRz R31; is provided and each individual aerial RA1 or RAn of this auxiliary system is energized by oscillatory energy of suitable phase derived from the corresponding main aerial A1 or An through feed line f1, f2 fn connected to the aerials by suitable coupling means such as by inductance coils C and CR, respectively. The energy fed to the auxiliary aerials is amplified 5 by amplifiers Aml, AmZ Amp. which are inserted, as shown, in the feeders f1 fn- Ihave furthermore shown a receiver RC of any known design connected to the aerials A1 An such as through coupling coils C or by means of any other coupling as may be desired.

In a system as above described, a radio signal incident upon the antenna system A1 An is amplified in amplifiers Ami Amp. and is fed back by radiation from the auxiliary or reaction 5 antenna system RA1 RAH to the main antenna system A1 An as indicated by the arrows A in Figure l and in this way regeneration of the signal is obtained. Further, as will be seen from the following description, only signals coming from the desired direction are regenerated.

Referring to Figure 3 which shows a polar receiving diagram of an antenna system according to Figures 1 and 2, the directional characteristic of the main antenna and reaction antenna system are as indicated at A and B, respectively. In these characteristics the section from the points 0 or I to an inter-section point of the curve with a line drawn in a desired direction is proportional to the receiving field strength of a signal arriving in this particular direction, as is well known. Then, assuming the same phase relationship or delay between the currents in each individual main aerial and the corresponding auxiliary aerial, the said signal will be regenerated to the greatest extent, since if another signal on the same wave length is coming from another direction II-O, then the directional characteristic C of the reaction antenna for tlr's signal is rotated by an angle 5 and this particular signal is not regenerated or is regenerated to a much less extent. The reason that the directional characteristic of the reaction antenna system is now shifted is that the individual aerials RAi The relative phases are the same as those produced in the individual aerials A1 All by the signal incident thereon at an angle at to the plane of the antenna system A1 An. In the system above described therefore, a signal coming from the desired direction is regenerated and all signals coming from other directions are substantially not regenerated. In consequence, the overall directional characteristic of the system as a whole is greatly improved as represented diagrammatically by the characteristic B according to Figure 4 as compared with the characteristic A without reaction.

The reaction of course can be made controllable and hence adjustment for any desired sharpness or degree of sensitivity obtained. Moreover, if relative phase shifts; that is, different time lags, are introduced in the reaction feeders f1 fn, then the resultant direction of maximum sensitivity can be rotated, i. e. as indicated at C in Figure 4.

The provision of reaction in accordance with the invention has the advantage that not only is the directional sensitivity greatly improved but the frequency selective properties, for the signal from a desired direction only, are also improved and the desired signal enormously increased in strength, the improvement compared with known directive antenna systems being considerable.

A' system in accordance with the invention is moreover less expensive not only from the point of view of initial cost but also from the point of View of operation and maintenance. The main antenna system can be constructed of fewer elements, the height can be reduced, the reaction antenna can be of a very small height (wires only three meters in length suspended on cheap wooden poles have been successfully employed for this purpose), the reaction feeders can be also small and inexpensive since the losses are largely covered by reaction, the main feeder leading to the main receiver can be also less expensive since the large gain of the system will largely overcome the losses occurring therein, and the complication of using separate individual reaction amplifiers in the embodiment above described is largely oifset by the simplicity of the main receiver which can be used.

In the arrangement shown in Figures 1 and 2, a separate reaction amplifierAmi Amn is provided in each feeder connecting a main antenna element with a corresponding reaction antenna element. Such an arrangement is however not essential unless it is desired to obtain control o RAH are fed with phase shifted currents.

the direction of maximum sensitivity, and in the arrangement shown in Figures 5 and 6 showing a modification of the apparatus according to Figures 1 and 2 and explanatory vector diagrams as shown by Figures 7 and 8, a single reaction amplifier Am is employed. In these figures A1 An are the individual aerials which with the reflectors R1 Rn constitute the main antenna system connected by means of a feeder line f to the receiver RC. From any point of this feeder line, or from any convenient point in the circuit of the receiver RC, a tap M is connected to an amplifier or reaction adjusting device Am and from this point the reaction currents are transmitted over a feeder line I" to a single reaction antenna RA, which may be directional or non-directional. The reactive radiation traverses paths such as shown by the arrows a, b, c a: to the various antenna elements and if the signal is coming from the desired direction the reaction currents in (Fig. 7) will be in phase with the currents in, i132, in; and in in the example shown in the various individual aerials A1, A2 An; if the signal is coming from any other direction, then the reaction currents in will not be in phase with the currents in, irz, ir3 and "14 induced by the signal (Fig. 8) Instead of the reaction antenna RA, reaction coils reacting upon every single antenna A1 An may be used. However, a reaction antenna is more convenient and more easily constructed.

Another arrangement utilizing a non-directional reaction antenna is shown in the accompanying Figure 9 wherein FA1 and FA2 represent two frame aerials spaced at a distance 11. Reaction energy from amplifiers Ami and AmZ is fed to two or, if desired, a single non-directional antenna RAi and RAz which maybe one or two meters in height and situated near together. For a signal coming from the direction I-O, the phases of the reactive antenna currents in RA1 and HA2 will be equal, but for any other direction the phases will be shifted by an angle depending upon the direction of the signal and spacing d. Any shifting of the currents in RAi and HA2 means however areduction in the feed back energy reacting upon the frame aerials FAi and FAz.

Therefore the ordinary figure of eight characteristic of two frames separated by a distance d which is small in comparison with the wave length used will be drawn out and become something like that shown at K in Figure 10 compared with the ordinary figure of eight diagram shown at K'.. A cardioid diagram for such an arrangement will be similarly improved as shown in Figure 11 in which K and K represent the diagrams for the two cases; i. e. without and with radiation regeneration in accordance with the invention. Instead of using reaction antennae RA1, RAz, reaction coils may be employed but in such case the coil or coils fed from amplifier Aml must react upon both antennae FA1 and FA2, and in the same way the coils fed from the other amplifier AmZ must react upon both antennae.

Of course, the sharpening effect on the directional properties is more pronounced if both the main antenna and the reaction antenna are directional. It is desirable to choose very sharp directional characteristics for the reaction antenna but these need not be uni-directional. For instance, characteristics as shown in the accompanying Figure 12 or 13 can be used with good results.

The reaction amplifiers employed may comprise any desired number of stages which may be tuned or aperiodic but for good results it is essential that the amplification be linear so far as is possible. This condition is not difficult to attain if the grid swing on the amplifier be kept small. The degree of amplification necessary depends naturally upon the distance of the reaction antenna from the main antenna and upon the losses occurring in the feeders. If a large degree of amplification is necessary, the superheterodyne principle may be used and the intermediate frequency must then be changed again to the original frequency. This can be easily done by means of a single local oscillator for all amplifiers. The intermediate frequency heterodyned with the local oscillator frequency will yield the original radio frequency since n0nh+nh=no is the original signal frequency and m is the heterodyne frequency and -121; is the intermediate frequency. Such a system is very convenient because by adjusting the heterodyne output applied to the various reaction circuits the degree of reaction can be controlled easily and simultaneously for all the circuits.

Furthermore, by using a single heterodyne oscillator and adjusting the phases of the heterodyne oscillations applied to the various circuits, the rotational adjustment of the direction of maximum sensitivity may easily be performed. If the superheterodyne principle be not used for adjustment of reaction the output of all amplifiers Aml Amn may be made adjustable in any known manner, e. g. by means of potentiometers, variable coupling systems, variation of the potential of the screen grids, variable mu valves, etc., and naturally for convenience it is preferable to couple mechanically or synchronize in any known manner the individual adjustments of each amplifier. The adjustment of the outputs of all amplifiers Aml Amn must of course be equal in order to obtain in every case equal currents in all the individual aerials of the reaction antenna.

In order to rotate the over-all beam characteristic it is necessary, as pointed out, to provide additional phase shifts in the reaction feeders, for instance, with the following phase relationship: feeder f1phase 1:0, feeder fzphase 21, feeder f3phase 3=2, feeder fnphase One method of efiecting this phase shift is by adjusting the lengths of the individual feeders. If it is desired to make this adjustment uni-controlled it is preferred to employ the superheterodyne principle as previously described since otherwise unicontrol, although not impossible, is difficult of achievement in practice.

The reaction amplifiers can be mounted in a hut between the main antenna and the reaction antenna or as shown in Figures 14 and 15 in the main receiving building. In this latter case from each unit antenna A1, A2, A3, A4, individual feeders f1, f2, f3, f4 transmit the currents to the reaction amplifiers Aral, Am2, Am3, Ami. From the output terminals of each amplifier a feeder f1, f2, f3, f4 transmits the reaction currents to one unit of reaction antenna RAi, RAz, HA3, RAi. From the input side of the amplifiers the feeders are combined and transmit the currents to the receiver RC. On the heterodyne unit indicated diagrammatically at H, two controls may be 3.1? ranged, control N for controlling of the reaction which may consist of a variable coupling for all the first and possibly for the second detectors or means for varying the bias for variable-mu valves, and the other control Pfor controlling or rotation of the whole beam characteristic, such as by means of ganged condensers.

A system of the above mentioned type is more clearly shown in Figures 16 and 17 which in general correspond to the arrangement as shown in Figures 1 and 2 with the exception of the provision of superheterodyne amplifiers and phase shifting means for adjusting the directional characteristic. The amplifiers shown comprise first or input mixer stages HA1 HAn supplied from a common local oscillator shown at 0. The mixing of the input frequency currents with the local frequency current supplied by the oscillator 0 may be carried out in accordance with any one of the known methods such as by means of specially designed electron tubes known as electronic mixers. The intermediate frequency currents obtained from the output of the first mixer stages are then amplified in the usual manner by means of intermediate frequency amplifiers shown at IA1 IAn. After amplification at intermediate frequency the signals are again returned to their original frequency in accordance with the invention by means of second frequency changing or mixer stages shown at HA1. HAn' wherein the same local oscillator shown at 0 may be used to supply the mixing or heterodyning current in such a manner as to obtain the original signal frequency by beating of the intermediate frequency currents with the local frequency currents supplied by the oscillator O. I have shown further high frequency amplifying stages HA1". HAn" for increasing the amplitude of the restored signal which directly feed into the reaction antennae RA1 R-An in a manner similar as described in the preceding figures. Items P1 Pr), represent phase shifters such as variable condensers in the supply leads 'from the local oscillator O to the second mixer stages preferably provided with a common control means, indicated at K, such as is customary with gang condensers for simultaneously adjusting the output phases for varying the direction of the receiving characteristic of the entire systern in a manner as described hereinbefore.

The invention is of course not limited to the arrangements described and shown in the accompanying figures. Various other combinations are possible provided that in the main aerial spaced unit antennae are used from which various phases are fed through one or more amplifiers to the reaction system. The reaction system can be constituted by a directive or non-directional aerial or else reaction coils as previously described.

It is important of course for the good working of the system to have a smooth reaction control. This can be obtained in any known manner, for example, by the use of leaky grid detector valves as special reaction valves whose output may be amplified if necessary. By pushing reaction near to its critical value, just before oscillations occur, exceedingly sharp directive characteristics can be obtained in a manner which is analogous to the high frequency selectivity obtainable in the known frequency reaction circuits. In this manner, the beam may be confined within an angle of a half degree.

In the foregoing description improvements of the directional characteristics in the horizontal plane only have been considered. It is however also possible, according to the invention, to improve the vertical characteristics. For this purpose a reaction antenna may be used in which standing the reaction beam is caused to swing in the vertical plane.

Itwill be seen from the above description of my'invention that the directional selectivity or degree of sharpness of a direotivewireless .an-

tenna system is considerably increased by the @may be made without departing from the spirit and scope of the claims appended hereto.

I claim:

A directional system comprising a directional receiving antennahaving its line of maximum receptivity pointing in the direction of .the transmitter being received, means for amplitying signals received by said antenna, and an auxiliary antenna connected to said amplifying means and located substantially on a line joining the receiver andthe transmitter for. radiating a portion of the amplified received signals,v whereby signals incident upon the system from the transmitter are differentially accentuated by regenerative radiation from said auxiliary I ant nn 7 2. A systemv as claimed in claim 1 including phase shifting means between said amplifying means and said auxiliary antenna.

3. A system as claimed in claim. l in which i said auxiliary antenna is a non-directional antenna a l 4. A systemas 'claimedinclairn .l in which said auxiliary antenna is a directional antenna having its direction of maximum radiation in line with the direction of maximum receptivity of said receiving antenna.

5. Adirectional receiving system comprising a plurality of antenna elements adapted to ab sorb incident electromagnetic wave energy at different phase angles dependent on the direction of incidence of the energy being received, means for combining the energies received by said antenna elements for directive reception, a reaction antenna arranged at a predetermined relative location to said antenna elements, circuit connections between said antenna elements and said reaction antenna, means included in said circuit connections for adjusting the phase of the energy fed to said reaction antenna, and further means included in said circuit connections for changing the frequency of the reacting energy derived from said antenna elements to intermediate frequency energy, amplifying the intermediate frequency energy and changing the frequency back to the original frequency before application to said reaction antenna.

6. A directional receiving system comprising a plurality of antenna elements adapted to absorb incident electromagnetic wave energy at different phase angles dependent on the direction of incidence of the energy being received, means for combining the separately received energies for directive reception, a reaction antenna arranged at a predetermined relative location to said antenna elements, circuit connections between said antenna elements and said reaction antenna, means included in said circuit connections for adjusting the phase of the reacting energy fed to said reaction antenna, and

further means including a single local oscillator for heterodyning the frequency of the reacting energy to'intermediate frequency energy, amplie fying the intermediate frequency energy and I heterodyning the amplified energy to restore the original frequency before application to said re,- action antenna.

7. A directional receiving antenna system comprising a plurality of spaced antenna elements, means for combining the energy picked up by said elements in the required phase relationship for directive reception, means for amplifying the combined energy and means for radiating a portion or the amplified energy. from a point lying substantially in a line joining the receiver and the transmitter whose signals are to be received whereby signals incident upon the system from said transmitter are differentially accentuated by regenerative action by said radiation.

8; Av directional antenna system comprising a plurality of spaced antenna elements*'-' constituting a main directionalreceiving antenna, a further corresponding plurality of spaced antenna elements constituting an auxil iary directive antenna, means for separately amplifying 'energy picked up by individual main antenna elements, and means for feeding said separately amplified energies individually to cor-. responding elements of I said auxiliary antenna whereby said auxiliary antenna is caused to radiate energy differentially reacting upon the elements of saidmain antenna in such a manner as to accentuate signals incident uponsaid main antenna from a predetermined direction.

9. A directional antenna system comprising a plurality of spaced antenna elements constituting a main directional receiving antenna, a further corresponding plurality of spaced antenna elements constituting an auxiliary directive antenna, means for separately amplifying energy picked up by individual main antenna elements, means for feeding said separately amplified energies individually to corresponding elements of said auxiliary antenna whereby said auxiliary antenna is caused to radiate energy in such manner differentially reacting upon said main antenna elements so as to accentuate signals incident upon said main antenna from a predetermined direction, and means for introducing an adjustable relative phase shift between the reacting energies derived from individual antenna elements whereby the direction of maximum sensitivity of the system may be adjusted.

10. A directional antenna system comprising a plurality of spaced antenna elements consti tuting a main directional receiving antenna, a further corresponding plurality of spaced antenna elements constituting an auxiliary directive antenna, means for separately amplifying energy picked up by individual main antenna elements, means for feeding the separately amplified energies individually to corresponding elements of said auxiliary antenna whereby said auxiliary antenna is caused to radiate energy differentially reacting upon said main antenna elements in such manner as to accentuate signals incident upon said main antenna from a predetermined direction, and means for introducing an adjustable relative phase shift between the reacting energies derived from individual antenna elements whereby the direction of maximum sensitivity of the system may be adjusted, the energy for reaction being heterodyned to and amplified at an intermediate frequency and then again heterodyned to the original frequency before application as reacting energy.

11. A directional antenna system comprising a plurality of spaced antenna elements constituting a main directional receiving antenna, a further corresponding plurality of spaced antenna elements constituting an auxiliary directive antenna, means for separately amplifying energy picked up by individual main antenna elements, means for feeding the separately amplified energies individually to corresponding elements of said auxiliary antenna whereby said auxiliary antenna is caused to radiate energy differentially reacting upon said main antenna elements in such manner as to accentuate signals incident upon said main antenna from a predetermined direction, and means for introducing an adjustable relative phase shift between the reacting energies derived from individual antenna elements whereby the direction of maximum sensitivity of the system may be adjusted, said first means comprising a single local oscillator for heterodyning the energy for reaction to an intermediate frequency, amplifying and heterodyning the intermediate frequency energy to the original frequency before application as reacting energy.

12. A directional antenna system comprising a plurality of spaced antenna elements comprising a main directional receiving antenna, a further corresponding plurality of spaced antenna elements constituting an auxiliary directive an,

tenna, means for separately amplifying energy picked up by individual main antenna elements, means for feeding said separately amplified energies individually to corresponding elements of said auxiliary antenna whereby said auxiliary antenna is caused to radiate energy differentially reacting upon said main antenna elements in such manner as to accentuate signals incident upon said main antenna from a predetermined direction, said first means comprising a single local oscillator for heterodyning, the energy for reaction to an intermediate frequency amplify-l ing and heterodyning the intermediate frequency energy to the original frequency before application as reacting energy, and means for adjusting the phase of the local oscillation produced by said oscillator.

13. A directional receiving antenna system comprising a plurality of spaced antenna elements reflector elements being associated with said spaced antenna elements, means for combining the energy picked up by said elements in the required phase relationship for directive reception, means for amplifying the combined energy and means for radiating a portion of the amplified energy from a point lying substantially in a line joining the receiver and the transmitter whose signals are to be received to produce a differential regeneration upon said antenna elements whereby signals incident upon the system from said transmitter are accentuated by regenerative action by said radiation.

J OZEF PLEBAN SKI.

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