US1935375A - Beam receiving system by frequency multiplication - Google Patents

Description

NOV. 14, 1933. l J. PLEBANSK| 1,935,375

BEAM RECEIVING SYSTEM BY FREQUENCY MULTIPLICATION Filed Feb. 17, 1930 BY LQ 69M rae-.nad Nev. i4, i933 Vriant 1,935,375 anar/i anonivinc sivs'rnin er FnEQUcNcr 'rrrLroA'rroN v ,A

Jozef Plebanski, Warsaw,' Poland, assignor 'to Radio Corporation of' America, New York,

N. Y., a corporation of Delaware Y Applicatin February i7, 1930, serial No. 428,998, and in )Poland March, 1329' A 'I This invention relates' to directive antenna systems, and more particularly to'such of these which utilize a plurality of aerials, suitably spaced apart, for receiving'pur'poses.

It is well known in the art that spacing between the individual aerials of such directive-receiving systems is a factor which depends upon the Wave length `of the signal to be received.'

, `'I'hesesysterns are usually designed to receive with high efciency signals incoming from one direction and to discriminate against signals from other directions. Such result is effected by making the phases of' the. currents. induced inl the system by the signal incoming from the desired direction additive in character so as to give maximum current density while making the phases of the currents induced by signals from other undesired directions opposite in character'so as to cancel out. y

The invention is more fully described in connection with the accompanying drawing wherein,

Figure 1 diagrammatically illustrates a pair of vertical antenna and Various directions of waves impinging thereon,

Figure 2 illustrates one form of the present invention,

Figure 3 is a diagram illustrating the operation of the apparatus shown in Figure 2,

Figure 4 illustrates an embodiment of my invention utilizing four spaced antennae,

Figure 5 is a characteristic curve of my arrangement shown in Figure 4, and,

Figure 6 illustrates a modification of my in- Vention wherein received waves are obtained to lower intermediate frequencies before being frequency multiplied.

Referring to Figure 1 of the drawing, there are shown two antennas A and Bspaced apart a distance d. For a wave being received from direction I the currents induced in A and B will be in phase, the resulting total current being twice as great as the current in either one of the two antennas.

On the other hand, for a wave incoming from direction III in the plane of the two antennas,

there will be a phase difference in the currents in-, duced in A and B which may be represented by the equation Y 21rd t T y where d is the antenna spacingV and A the wave length. If, now, the spacing is made equal to a half wave length iigure then ,4) will equal 180"` Yand the sum ofthe currents in the two antennas will be Zero. Similarly, if ffd equals gigqb will'equal or 22 Y3Q and the; surn` of thecurrents induced by thesignal coming from'direction III will not be zero... u

But if we arrange the two antennas according to the Fig. 2 andfby means of arbitrary frequency changersA (frequency 'transformers orvalve frequencyv changers) westep up the frequency 48k times (i. ertimes ydoubling the frequency) `then we can prove, that the phase difference between currents in anodes of the valves lc, Z will be 8 times greater than direct in antennas I kand II.

If we have for instance square law detectors,

then the detector current can be shown by the Aif e=uA sin (wt+)+B sin pt sin (wt-agb).

AB sin ptrcos @wt-eht] From the above it is clear that by frequency doubling the phaseshiiting is also doubled.

It can be proved, that if we have any frequency changing arrangement which increases the frequency 2, 3 n times then the phaseshifting (relative phase) will also be increased 2, 3 11. times. g

Therefore spacing aerials for instance at c1=s and increasing the frequency according to Fig. 2-8 times we can get the same directional characteristics, as with spacing of aerials, but saving much room. l

By combining according to Fig. 2 two directional systems having each cardioid reception diagram (Fig. 3) we can get an improved characteristie sho-wn by 1 and 2 on Fig. 3. l.

In this way any systems (or aerials) nondirective or directional` can be combined and the di-v rectional characteristic can be improved.

Therefore by adequate spacing the used wavelength can be too short. l

To obviate this, we can utilize the superhetero dyne principle and rst of all change the incoming signal to the greater wavelengthl (Fig. 6).

The used heterodyne (one or more) ,can feed roo all circuits at the same time. The intermediate l Y Wavelength can then be reduced (frequency increased) by means of frequency changers. The directional results Will be the same as above, but the construction will be much plainer and easier. Adjust-ing the phases of heterodyne 'toea'ch circuit separately the beam can be rotated.

The increased intermediate frequency 'can be stepped up to the (ab) original Wavelength of signal and then regeneration may be utilized as indicated in Fig. 6. f

Referring to Figure 6 in more detail, 'it will -be seen that the intermediatev frequency .can be stepped up to the same amount a'svb'efore hetero'- dyning to obtain a frequency Which may Abe .represented by the equationr2(V-TV0)K=V, Where V is the .signal frequency and A'Vo the -heterordyne frequency. For example, for asignal frequency of 800 kc and heterodynefrequency of .'700 kc then V-VczlOO kc and 2 (100)=23 G00) :800 kc. From the foregoing, it will be seen that for three times frequency doubling (2 '2 2=`8 times) :of the 'intermediate tfrequency 1'00 V`kc, there is obtained the same frequency as the original. This frequency can :be used to regenerate the receiverrupon the input side. Of course, the multiplied-'output frequency must v'ibe the same or about fthesame fas the original :sig-nal frequency.

Only in this case, this method of regeneration or reaction fmay'beused. 'By using this kind -cf reaction on each antenna al'stillfb'etter directional characteristic 'is obtained. In Figure 16 such arrangement is shown with only twoantennas. rOf course, any vnumber kof .antennas may be used.

Each antenna or antenna system is associated with one receiver in which the signal frequency is reduced by means of a heterodyne Vu to the intermediate frequency V-Vo Which is then multipled by means'of valves or other arrangements between points c, d and-c d" until va. frequency 2n Y (V-Vo) is obtained, and if this frequency is equal to 'the signal frequency V it may be used for regeneration purposes. The combined output is fed to the peints c, b.

In this Way less quantity ofvalves can be used.

Furthermore the antennas from Fig. 4 can be for linstance combined -rstly every two then every three and finally the sum current of all four can `'beit-alien.

l Using this kind of intercombination with frequency multiplication still better directional characteristics can be got.

With :five antennas for instance al1 1A; A wide by ysuitable combining and frequency multiplication the same Adirectional `characteristic can be got as with '1'01/2 A Wide beam :receiving aerial.

- What iisclaimedis: v 'I In a radio receiving system, a :plurality of spaced rantennae,'means for heterodyning 'the 'A eratively amplifying ,said frequency multiplied energy, .and means for .combiningthe frequency multiplied .energy whereby "the directive charac-- is improved.

teristic fof saidV antenn y JOZEF PLEBANSKI.

Images