US 3377592 A
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April 9, 1968 J. ROBIEUX ETAL 3,377,592
ULTRAHIGH-FREQUENCY AERIALS Filed Nov. 24, 1959 5 sheets-shed 1 INVENTORS JEA N ROB/E UX ROGER DUMANCH/N April 9, 1968 J. ROBIEUX Em. 3,377,592
ULTRAHIGH-FREQUENCY AERIALS IN VENTORS JEAN ROB/E UX ROGER DUMA NCH/N April 9., 1968 J. ROBIEUX ETAL 3,377,592
ULTRAHIGH-FREQUENCY AERIALS Filed Nov. 24, 1959 5 SheetS-Sheet b PHASE DISCRIMINATOFL .SOURCE INVENTORS JEAN ROB/EUX ROGER DUMANCH/N 3,377,592 ULTRAHlGH-FREQUENCY AERIALS Jean Robieux and Roger Dumanchin, Paris, France, as-
signors to Compagnie Generale de Telegraphie Sans Fil, a corporation of France Filed Nov. 24, 1959, Ser. No. 855,233 Claims priority, application France, Dec. 5, 1958, 780,930 4 Claims. (Cl. 343-100) The present invention relates to ultarhigh-frequency directional aerials. More particularly, it relates to electrically controlled aerials, i.e. to aerials of the type wherein the scanning of the space is obtained electrically without actual rotation of the aerial.
It is an object of the invention to provide an improved aerial of this type and it is a Ifurther object of the invention to provide an aerial of this type which is particularly adapted for being supported on a flat surface in such a way that any interference with the aerodynamical characteristics` of a ilying body provided with this aerial is avoided.
An aerial according to the invention comprises an assembly of parallel transmission lines having equidistant radiating discontinuities, a wave guide for feeding energy to the aerial, a ferrite rod extending axially of the guide and a coil structure surrounding the guide for providing therein a magnetizing tield directed along the axis of said ferrite rod.
The transmission lines may be microstrip lines, the radiating discontinuities being built up by line lengths where at least one edge of the line is shifted laterally with respect to the general direciton of the line, as more particularly disclosed in the copending Patent Application Ser. No. 855,234, filed Nov. 24, 1959.
According to a particular embodiment of the invention, cach radiating discontinuity is shifted lengthwise of the line with respect to the corresponding discontinuity of the adjacent line, in such a manner that the phase velocity of the wave in the guide is higher than the velocity of light.
The invention will be best understood from the following description and appended drawing wherein:
FIG. l is a perspective view of an aerial according to the invention;
FIG. 2 is a cross sectional view of the aerial of FIG. 1;
FIG. 3 is a partial top View of the aerial of FIG. l;
F IG. 4 is an explanatory diagram;
FIG. 5 is a variation of FIG. 3;
FIG. 6 is an explanatory diagram;
FIG. 7 shows an aerial according 4to the invention, mounted on the wings of a high speed flying body;
FIG. 8 is a block-diagram of a control device;
FIG. 9 illusrtates, very diagrammatically and in crosssection, a further aerial according to the invention.
The radiating device shown in FIG. 1 comprises a rectangular Wave-guide 1 along the axis of which extends a ferrite rod 2. Coils 3 are wound around Wave-guide 1 and generate therein a magnetic field H directed along the axis thereof. l
A plurality of microstrip lines having a common ground plate 5, a common dielectric plate 8 and strips 6 extend in perpendicular relationship to the axis of guide 1. They are coupled to guide 1 by means of probes 4 and are spaced apart by M2, where )t is the length in free space of the operating wave.
Strips 6, which are otherwise of a known type, comprise radiating discontinuities 7. These ydiscontinuities are spaced apart by as, )ts being the wave length in the line of the operating wave and are obtained by laterally shifting portions of at least one of the edges of the line.
United States Patent O Patented Apr. 9, 1968 f. ICC
FIG. 2 shows a cross-sectional view of the assembly shown in FIG. 1. Ground plate 5 is supported on a block 9 which rests on one of the large sides of guide 1. Each block 9 comprises a hole 10 which is lined with the dielectric material forming plate 5. This material builds up the outer conductor of a co-axial cable. Probe 4, which extends into guide 1, forms the inner conductor of this coaxial cable.
FIG. 3 shows the strips as seen from above. Four strips 61, 62, `63 and 64 are shown. Discontinuities 7 build up rows spaced apart by M2 and columns spaced apart by ks, as mentioned above.
The radiating assembly of FIG. l operates as follows:
Considering first only the rows it is apparent that all the discontinuities 7 of a line are fed in phase. Consequently, the assembly radiates in the mean plane of the large sides of guide 1.
If, now, the columns built up the radiating elements 7 respectively pertaining to lines 61, 62, 63 and 64 are considered, they radiate in a plane making with the plane comprising strips 6 an angle 0 delined by the well known equation cos M Thus, the radiation direction is define-d by the intersection of the two planes mentionied above, this direction being inclined to the plane containing strips 6 and making therewith angle 0.
According to the invention, this angle can be modified.
It is known that a ferrite piece placed in a guide and subjected to a longitudinal magnetic field modifies the phase velocity of the wave propagating therein. This phase velocity varies as a function of the magnetic field, the corresponding curve having the shape of a hysteresis loop, as shown in FIG. 4 where Vg is the phase velocity of the Wave in guide 1 and I the intensity of the current owing in coils 3.
If the phase velocity is higher than the velocity of light, i.e. if xg is greater than c, the aerial has a .maximum directivity along a direction forming an angle 92 with the axis of guide 1, with If, however, the presence of ferrite 2 in guide 1 delays the wave propagation suiciently Afor Vg to become smaller than c, this is no longer true, since c/Vg is greater than 1.
In this case, particularly in order to make the radiation possible in spite of the presence of the ferrite in guide 1, the apparent or phase velocity of the wave propagating in the guide in the direction of the axis of the guide must be rendered artificially greater than the velocity of light.
VReference is made in this respect to FIG. 6 where the variations of phase of the wave propagating in guide 1 are plotted along the axis of ordinates against distances taken along the axis of the guide taken as abscissae.
The propagating wave being expresse-d by Z Z e (w g 7D- -I-g Accordingly, go=f(Z) is a straight line, the slope of which is inversely proportional to Vg. l
In FIG. 6 curve 1 corresponds to Vg=c, curve 2 to Vg c and curve 3 to Vg c.
As may be seen from FIG. 6, in order to pass from a point on curve 2 to the point of the same abscissa on curve 3, it suliices that, at the point of guide 1 having this abscissa, the wave is delayed by p=KZ, K being a constant. Such a phase-shift may be obtained by a suitable arrangement of the elementary radiating sources, i.e. of discontinuities 7.
This is achieved in the arrangement of FIG. 5. The respective discontinuities 7 of lines 61 and 64 no longer built up columns, but are laterally shifted with respect to each other by the same distance to form a staggered arrangement.
FIG. 7 shows a missile 100 having wings 101 to which an aerial 102 according to the invention is applied. Arrows indicate directions of radiation. They make with wings 101 an angle 0 which can be modified by modifying the magnetic iield to which the ferrite element is submitted. The printed-circuit techniques allow of a great precision in the manufacturing of aerial structures according to the invention even in the millimeter band.
High directivity aerials may thus be readily provided. For 1 mm. wavelength, a pencil-beam of a beam angle of 1/1000 radians may be readily obtained with an aerial extending over 1 metre.
An aerial according to the invention which is capable of scanning space without actual rotation of any mechanical element is susceptible of many applications. Wide angular sectors may thus be scanned in very short periods of times: for example, a sector of 45 may be scanned in 1 mms.
FIG. 4 shows that phase velocity Vg is not a univocal function of the magnetizing eurent I. Accordingly, if I is known, angle is not necessarily known. As shown in FIG. 8, a phasemeter 200 `can be used for determining 0. Since c i/fi.
0 is known if Vg is known.
Phasemeter 200 measures the phase `diilerence of the wave between the points A and B in the mean plane of guide. Accordingly it measures the phase velocity Vg.
In order to reduce insertion losses, due to the insertion of the ferrite elements into the guide, and the secondary lobes, the aerial assembly may be built up as shown in FIG. 9. It comprises two aerial structures similar to those described so far and respectively comprising guides 101 and 102 placed end-to-end. Guides 101 and 102 comprise respective ferrite rods 201 and 202 as explained above.
Coils 301 and 302 surround guides 101 and 102 respectively. Guides 101 and 102 respectively support ground plates S01 and 502 and the strips are coupled to the guides by means of probes 401 and 402. A guide 103 feeds energy to guides 101 and 102, the energy flowing in opposite directions in the two guides. Two probes are located at points A and B, symmetrically with respect to the axis of guide 101.
A phase discriminator 104 provides a control voltage which is a function of the phase difference at A and B. This control voltage controls in any suitable manner the energy fed from a source 105 to coils 401 and 402 in such a manner that pA= pB- Referring now to FIG. 6, it is readily seen that if curve 2 corresponds, as explained above, to the function p=f(Z), for example in guide 101, curve 4 making with the axis of abscissae the same angle as curve 2 corresponds to p=f(Z) in guide 102. Under these conditions if, as also explained above, g0=f(Z) is shifted from curve 1 to curve 3 by suitably shifting the radiating sources with respect to each other, it will suflice to shift suitably with respect to each other the radiating sources fed from guide 102 in order to have along guide 102 a phase propagation corresponding to to the angle 0, if this angle is 0 in the case of the aerial portion fed from guide 101. Thus it appears that both aerial sections 101 and 102 will radiate in the same direction.
Of course the invention is not limited to the embodiments shown and described which were given solely by way of example.
What is claimed is:
1. An ultrahigh-frequency directional aerial, comprising in combination: a waveguid e for propagating ultrahigh-frequency energy; at least one set of parallel identical microstrip lines, extending in a direction perpendicular to said wave guide and spaced apart by one half of the wave length in fre space of said energy; means for coupling said strips to said guide; said microstrip lines having radiating discontinuities spaced apart in each line by a wave length of said energy in said lines, said discontinuities forming in each of said sets rows inclined over the symmetry plane of said guide; at least one ferrite rod extending along said wave guide; and coils surrounding said rod for controlling the phase velocity of the ener-gy in said wave guide.
2. An ultrahigh-frequency directional aerial comprising in combination: two wave guides having a common input for propagating ultrahigh-frequency energy in opposite directions; two sets of parallel identical microstrip lines, extending in a direction perpendicular to said wave guides, the distance between two consecutive strip lines in a set being equal to one half of the wave length of said energy in free space; means for coupling said strips to said guides; said vmicrostrip lines having radiating discontinuities, spaced along each line by a wavelength of the energy propagating therein, the discontinuities having the same relative position in each line being arranged in rows inclined over said guides; two respective ferrite rods extending in said wave guides; and respective coils surrounding said two rods for controlling the phase velocity ofthe energy in said wave guides.
3. An ultrahigh-frequency directional aerial comprising in combination: two wave guides having a common input for propagating ultra high frequency energy in opposite directions; two sets of parallel identical microstrip lines, extending in a direction perpendicular to said wave guides; the distance between two consecutive strip lines in a set being equal to one half of the wave length of said energy in free space means for coupling said strips to said guides; said microstrip lines having radiating discontinuities spaced along each line by a wavelength of the energy propagating therein, the discontinuities having the same relative position in each line being arranged in rows inclined over said guides; two respective ferrite rods extending in said wave guide; respective current conductive coils surrounding said rods for controlling the phase velocity of the energy in said wave guide; a phase discriminator coupled to said wave guides; and means controlled by said discriminator for controlling the current ow in said coils.
4. An ultrahigh-frequency directional aerial comprising in combination: a first transmission line for propagating wave energy: electrical means for controlling the phase velocity of said energy along said line; a plurality of parallel and equally spaced second trans-mission lines, coupled to said rst transmission line, said second transmission lines having radiating elements equally spaced from each other in each line, the radiating elements of said lines building up rows inclined over said rst transmission line.
References Cited UNITED STATES PATENTS OTHER REFERENCES Proceedings of the I.R.E., November 1957, pp. 1510- RODNEY D. BENNETT, Primary Examiner.
`CHESTER L. JUSTUS, Examiner.
R. E. BERGER, Assistant Examiner.