US2500178A - Ultra high frequency antenna structure - Google Patents

Description

March 14 1950 w. w. HANSEN I ULTRA HIGH FREQUENCY ANTENNA STRUCTURE Original Filed Jan. 16; 1942 2 Sheets-Sheet l Er. 3A

INVENTOR WILL/AM W. HANSEN I yQ M ATTORNEY March M, 1950 w. w. HANSEN uum HIGH FREQUENCY ANTENNA; smuc'rum:

2 Sheets-Sheet 2 Original Filed Jan. 16, 1942 TO PROBE 21s TO PROBE 2 l 5 TO RECEIVER INVENTOR W/LL/AM HANSEN ATTORNEY Patented Mar. 14, 1950 ULTRA man FREQUENCY ANTENNA STRUCTURE William W. Hansen, Garden City, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Original application January 16, 1942, Serial No. 426,986, now Patent No. 2,468,751, dated May 3, 1949. Divided and this application May 1, 1943, Serial No. 485,554

16 Claims.

This invention relates to directional antennas and particularly to ultra-high-i'requency antenna systems adapted to produce overlapping,

highly directional spatial patterns.

The present application is a division of copending application Serial No. 426,986, filed January 16, 1942, now Patent 2,468,751, issued May 3, 1949.

An object of the present invention is to provide an antenna system adapted to produce alternate and overlapping directional spatial patterns.

Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings, Fig. 1 is an oblique view of an antenna system comprising one directional wave guide radiator and two directional wave guide receptors as employed in the present invention.

Fig. 2 is an oblique view, partially broken away, of a portion of one of the wave guide receptors shown in Fig. 1.

Fig. 3 is an ideallaed elevation view of the shifting fan-shaped directional pattern employed in the present invention.

Fig. 3A is an idealized sectional view of the directional pattern shown in Fig. 3.

Fig. 4 illustrates an impedance matching transformer and commutator.

Figs. 5 and 6 show parts of Fig. 4 in detail.

Figs. 7 and 8 are sketches illustrating the operation of Fig.4.

In parent application Serial No. 426,986 there is disclosed a system for the location of objects by using a highly directional radiation pattern and overlapping, alternate, highly directional receptivity patterns. Also disclosed is a system using overlapping, alternate, highly directional radiation and receptivity patterns. The present divisional application relates to the novel antenna apparatus disclosed in the parent application for producing such spatial patterns.

The parent application discloses an ultra-highfrequency signal generator suitable for supplying energy to one of the antennas disclosed herein and two ultra-high-frequency receivers for detecting the energy received by the other two antennas disclosed herein.

Referring now particularly to Fig. l, rotatable pedestal 200 supports a yoke 20i which has a frame 202 swung between the arms of the yoke on trunnions. The right trunnion 203 passes through the yoke arm and forms the shaft of a gear 204 which is engaged to the driving pinion 206 of a motor 201. On the frame 202 are mounted wave guide radiator 208 and two wave guide receptors 209 and 2i0. Wave guides 208 and 209 are positioned parallel to one another,

z and wave guide M0 is positioned at right angles to wave guides 208 and 209.

The radiator 208 contains a probe located at the junction between each branch of the wave guide, and, when excited by an ultra-high-frequency signal, the radiator serves to produce a symmetrical, fan-shaped beam 01' electromagnetic energy which is highly directional in the plane determined by the axes of the two wave guides and broadly directional in a plane at right angles to this plane.

Receptors 209 and M0 contain within each receptor two probes positioned as explained below, so that the receptivity gain characteristic for each receptor comprises two unsymmetrical, fanshaped, overlapping patterns.

The wave guides employed in this antenna system are more fully discussed in copending application Serial No. 344,633 filed On July 10, 1940, now Patent No. 2,489,288 granted on November 29, 1949, in Patent No.- 2,402,622 granted on June 25, 1946, and in Patent No. 2,432,990 granted on December 23, 1947, each of these references being in the name of the present inventor. The wave guides areconstructed with two branches disposed at an angle with respect to each other of rectangular cross-section and oi. a length great compared to the other dimensions. The guides have narrow longitudinal slots on the opposed faces of the branches. Electromagnetic waves may be propagated from a radiator placed at the common junction or apex of the branches outwardly along their length'at a phase velocity dependent On the cross-sectional area for a given frequency. The radiation escapes through the slots and substantially none reaches the ends of the guides which may be left open. The direction of propagation of the radiated waves in free space forms an angle with their direction in the hollow wave guide whose cosine is the ratio of the phase velocity of the waves in free space to that of the phase velocity of the waves in said guide. Thus, at a particular frequency the two branches of a guide may be angularly adjusted to have a common direction of propagation of free space radiation along the bisector of the angle between the branches. Under these conditions there is obtained the fan-shaped beam desired for radiator 208.

Fig. 2 shows a possible arrangement inside wave guides 209 and 2i0. Probes 2i5 and 2; are mounted in wave guide branches 2H and H0, respectively, equi-distant from the common junction or origin of the guide. Slots 2| 9 and 220 enable the probes to be adjusted to a distance, preferably, one-eighth wave length from the origin. In operation, probes H5 and 2; in each of the receptors 209 and 2l0 are alternately activated and connected to detecting means through concentric lines I26 and I2! at a pre- 3 determined rate by a pair of suitable high frequency commutator switches.

When probes 2I5. and 2I6 of each of the receptors 209 and 2I0 are positioned one-eighth wavelength from the bisector of the angle between the branches of the wave guide, the gain characteristic of the receptor associated with each probe is an unsymmetrical fan-shaped pattern whose axis of maximum gain is shifted slightly from the bisector of the angle formed by the branches of the wave guides. The change in gain is more abrupt on the side of the spatial pattern adjacent to the bisector and less abrupt on the far side than in the case of an antenna placed at the bisector of the angle formed by the branches of the wave guides.

Figs. 3 and 3A indicate the overlapping spatial patterns representing the gain characteristic of the receptor indicated in Fig. 2. Each of these patterns is highly directional in the plane determined by the axes of the two wave guides and broadly directional at right angles to this plane.

The axes of maximum gain of the spatial lobes are equi-angularly displaced to each side of azimuth axis 300 of the locating system so that the gain characteristics of the receptors associated with probes 2I5 and 2| 6 are equal along azimuth axis 300. Principal lobe I60, having an axis of maximum gain 30I, represents the gain characteristic of the receptor associated with probe 2| 5, for example, and lobe I6I, having an axis of maximum gain 302, represents the gain characteristic of the receptor associated with probe 2I6.

In operation, if a target is within the combined receptivity patterns of the two receptors but is not within the pattern formed by the central axis of each pair of overlapping patterns, it refleets more energy to one of the probes than to the companion probe, and the amplitude of the signals in the detector will be greater when the former probe is connected by the switching device than when the latter is connected.

Figs. 4 to 8 disclose a commutator suitable for use with the antenna system disclosed herein. Parent application Serial No. 426,986 discloses the same commutator, and copending application Serial No. 664,764 filed on April 25, 1946, which is a division of the present application, discloses and claims this commutator.

Referring now to Fig. 4, there is shown the commutator disclosed in the copending application cited above. Concentric line I26 from probe 2I5 connects to a line I22 through the horizontal branches of a cross-shaped adjustable coupling I24, illustrated in Fig. in greater detail. In a similar Way concentric line I 21 from probe 2I6 connects to a line I23 through the horizontal rotated synchronously with the motor I5. Coupling I24, line I3I, box I33, shaft HI, and gear I31 are designed to b horizontally displaceable as a unit within a wavelength of the operating carrier frequency, for tuning purposes, as is the combination of coupling I25, line I32, box I34, shaft I42-and gear I38. The pinions I31 and I38 have lengths adequate to allow for these displacements. The distance between the centers of devices I24 and I25 and the shielding boxes I33 and I34, respectively, may also be vertically adjusted by means of the slidable attachment between the lower arm of the devices I33 and I34 and coaxial lines I3I and I32, respectively.

Fig. 5 is a detailed sectional view of the left portion of Fig. 4 revealing the method of joining the coaxial lines and the interior arrangement of shielding box I33. The inner conductors I22, I26 and I3I of the coaxial lines I22, I26 and I 3I, respectively, are hollow and of such an interior diameter as to permit the inner conductors I24 of the device I24 to slide therein.

I The exteriors of lines I22, I26 and I3I are likebranches of a cross-shaped adjustable coupling I25. Lines I22 and I23 join to form the coaxial cable I1 which connects the antenna system to detecting means. Vertical stubs of the couplings I24 and I25, projecting above the junction with the horizontal branches, contain adjustable shorting plugs I28 and I29, respectively. Vertical sections extending below the crossing adjustably attach to lines I 3I and I32, which latter issue from shielding boxes I33 and I34, respectively. Shafts HI and I 42, having attached pinions I31 and I38, respectively, project from the shielding boxes I33 and I34. Gears I39 and I40 on a shaft I36 mesh with pinions I31 and I38, respectively. A gear I43 on'the shaft I44 of the motor I5 engages the gear I40, and consequently the shafts HI. and I 42 through their associated gearing are wise enlarged to allow the exterior of the device I24 to slide therein. Insulating washers I46 and I41 support the inner conductors I24 coaxial with the exterior of device I24. An insulating washer I48 supports the inner conductor I3I. The ratio of the outside diameter of conductors I24 to the inside diameter of the exterior conductor of device I24 is made substantially equal to the ratio of the outside diameter of conductors I22, I26 and I3I to the inside diameter of their respective exterior conductors to maintain the characteristic impedances of the various sections equal. The shorting plug I28 is made with a hollow shaft to facilitate th longitudinal adjustment within the upright stub of device I24. The conductor I3I projects into the shielding box I33 where a condenser plate I49 is soldered to its end. The plan View of a preferred form of the plate I49 is shown in Figs. 7 and 8. The other plate of the condenser may be considered the adjacent side of the shielding box I33. The coaxial line I3I and the section of device I24 below the junction, therefore, is terminated by a capacitance whose magnitude depends on the area of the plate I49 and the spacing and dielectric constant between the plate and the side of the box I33. The shaft I4I, driven by the motor I5 through the gears I31, I39, shaft I36, gears I40, I43 and shaft I44, as mentioned above, rotates in ball-bearings I 5I and spins a doublebladed chopper I52 between the plate I49 and side of the box I33. Device I52 is roughly similar to a light chopper used in motion picture art. Fig. 5 moves one of the blades of the chopper I52 meshed as in Fig. 8. Fig. 6 is an alternate view of the box I33 taken at right angles to the plane of Fig. 5 looking from the base of the box at the end of the conductor I 3 I The chopper I52 may be constructed of a high dielectric constant, low loss non-conductor or may be made of a conductor which is insulated from the shaft MI. The effect of a non-conductor is to increase the capacity when meshed with plate I49 because the dielectric constant of the intervening space is increased. The effect of an insulated conductor is to create two condensers in series which have increased capacity due to the reduced air gaps, and the capacity of the series combination is greater than the capacity in the open position. The shielding box I 33 is dimensioned to be non-resonant to the transmitter frequency.

The operational alignment of commutator I 8 as shown in Fig. 4 is simplified by utilizing the teaching of the Reciprocity Theorem which allows the substitution of -an ultra-high-frequency oscillator in place of the detector on the end of the coaxial line I! to provide a temporary local power source. The alignment, which is undisturbed by this substitution, may be performed by the following steps:

First, mesh the left-hand chopper I52 as shown in Fig. 8 and adjust the length of the line from the plate I49 to the center of the coupling I24 until no energy flows down the left line I28 to probe 2i 5. This means there is an eifective short at the center of the coupling I 24.

Repeat this adjustment for the right-hand side of the apparatus shown in Fig. 4.

Next, unmesh the left-hand chopper I52 as shown in Fig. 7 and adjust the plug I28 in the stub of the coupling I24 until there are no sianding waves in the line I22. This means there is no reflection from the center of the coupling I24 I and energy may flow unimpeded to the left probe Repeat this adjustment for the plug I29.

Then, with chopper I52 meshed and th corresponding chopper in box I34 unmeshed, adjust the combined lengths of the right branch of coupling I24 and line I22, until there are no standing waves in the oscillator line IT. This means that when the center of coupling I24 is effectively shorted the oscillator" end of the line I22 is made to appear as an open circuit and there is no loss of power due to the short at the center of coupling I24.

Repeat this adjustment for the right side of the apparatus shown in Fig. 4.

Adjust the length of coaxial line I26 to the probe 2H5 with the chopper I52 meshed until the line has no field present indicating that the inactive probe 2i5 is absorbing no energy irom the active probe zit. This means that when the center of coupling I26 is effectively shorted, the antenna end of the line I 26 ismade to appear as an open circuit, and there is no loss of radiated power from the energized probe 2I6.

Repeat this adjustment for the right-hand line I2i.

These above steps are repeated until the alignment conditions are satisfied. The purpose of the stub line on coupling I24 is to couple a conjugate impedance to the center of coupling I24 which will compensate for the fact that the chopper I52 produces only a finite change of capacity.

The parent application discloses a system adapted to continuously orient an antenna system of the type disclosed herein so that the fanshaped overlapping patterns of each receptor are caused to continuously enclose the object to be located within the region defined by the central axis of each pair of overlapping patterns.

It will be apparent to one skilled in the art that the directional characteristics of the wave guide and probes indicated in Fig. 2, employed as receptors, apply equally to the wave guide and probes employed as radiators.

The parent application also discloses a system in which an antenna structure as indicated in Fig. 1 may be utilized employing two probes as shown in Fig. 2 in the radiator and in one of the receptors and employing a single probe placed at the junction between each branch of the wave guide in the other receptor.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof,

' and not in a limiting sense.

ISO

What is claimed is:

1. High-frequency apparatus comprising means for generating electromagnetic energy, transducing means mounted within a pair of hollow inclined waveguides, a transmission line connecting said generating means to said transducing means, impedance matching and commutating means employed in the line connection between said generating and transducing means, said communicatin means comprising variable impedance means eil'ectively varying th line impedance.

2. A high frequency apparatus comprising means for generating electromagnetic energy, transducing means mounted within a pair of waveguides, said waveguides forming a predetermined angle with respect to each other and having means for electromagnetically coupling said guides to surrounding space, a transmission line connecting said generating means to said transducing means, impedance matching and commutating means comprising variable imnected between said generating and transducing means, said commutating means comprising variable impedance means eiiectively varying the line impedance.

3. High frequency apparatus comprising means for producing partially overlapping fan-shaped radiation patterns comprising two hollow conducting radiating waveguides forming a predetermined inclined angle with respect to each other, means in each guide for alternately launching electromagnetic waves of substantially linear polarization for travelling along said guides, distributed means for radiating said waves extending along the length of said guides substantially at right angles to the electric vector of said waves, said launching means being spaced at a predetermined distance from the vertex of the angle formed by said hollow waveguides for introducing phase difierences between the electromagnetic waves at corresponding points within said guides so that nonsymmetrical overlapping patterns are alternately produced.

4. High frequency apparatus for producing partially overlapping fan-shaped radiation patterns comprising two hollow conducting radiating wave guides forming a predetermined inclined angle with respect to each other, means in each guide for alternately launching electromagnetic waves of substantially linear polarization for traveling along said guides, and distributed means along the length or said guides for radiating said Waves, said launching means being spaced at a predetermined distance from the vertex of said angle formed by said hollow wave guides and introducing phase difference between the electromagnetic waves at corresponding points within said guides so that unsymmetrical overlapping patterns are alternately produced.

5. High frequenc antenna apparatus comprising a pair of slotted rectangular wave guides disposed at an angle to one another, and means for coupling to said wave guides, comprising a pair of concentric transmission lines, the inner conductors of said transmission line being disposed within respective ones or said wave guides and symmetrically located with respect to the Junction of said wave guides.

6. High frequency antenna apparatus, comprising a pair of interconnecting hollow wave guides disposed at an angle to one another, each having means distributed along the length thereof for electromagnetically coupling said waveguides to the space surrounding said waveguides, and alternate transducing means for exciting said wave guides with travelling waves, whereby said apparatus has a pair of partially overlapping, alternate directivity characteristics.

7. High frequency antenna apparatus comprising a pair of intercommunicating hollow.

said waveguides, said waveguides further having openings extending along these major axes,

means for producing in said waveguides phase differences between electromagnetic waves at corresponding points within said guides, and control means alternately exciting said last named means, thereby producing partially overlapping directivity characteristics in space.

9. A high frequency apparatus for projecting alternate fan-shaped beams, comprising a pair of hollow waveguide intercommunicating sections inclined at'an angle of less than 180 with each other, transdueing means mounted within said hollow waveguide portions, means for producing in said Waveguide portions phase differences between electromagnetic waves at corresponding points within said waveguide portions, and commutating means cooperative with said transducing means to produce partially overlapping directivity characteristics in space.

10. High frequency apparatus comprising a hollow waveguide radiator, said radiator further comprising a pair of interconnected hollow waveguide portions disposed at an inclined angle to one another and having means distributed along the length thereof for electromagnetically coupling said waveguide portions to the space surrounding said. portions, and plural means alternately exciting said waveguide portions with travelling waves, whereby said apparatus has a pair of partially overlapping alternate directivity characteristics.

11. High frequency radiating apparatus comprising a radiator having a pair of hollow waveguide portions disposed at an angle less than 180 with respect to one another and having a common vertex, said waveguide portions having slots in the faces opposing one another for permitting radiation of high frequency waves from within said waveguides, means for exciting said waveguides, comprising coupling means located within each of said waveguide portions at a distance from said vertex, and means for alternately exciting said coupling means, whereby a pair of partially overlapping alternate directivity characteristics is produced.

12. High frequency radiant energy antenna apparatus comprising a radiator having a pair of hollow interconnected waveguid portions disposed at an angle with respect to one another to form a V, each of said waveguides having a slot in the wall thereof facing the other of said waveguide portions, coupling means mounted within each of said waveguide portions and displaced from the vertex of said V, and means for alternately exciting said coupling means, whereby said apparatus has a pair of partially overlapping alternate directivity characteristics.

13. High frequency antenna apparatus comprising a radiator having a pair of hollow waveguide sections disposed at an angle to form a V, each of said sections being aperturcd along the length thereof on the side facing the bisectrix of said V, and means for alternately exciting said waveguides with respective high frequency waves to produce partially overlapping alternate directivity characteristics in space.

14. High frequency antenna apparatus comprising a radiator having a pair of interconnected apertured hollow waveguides angularly disposed to form a V, and commutating means for alternately exciting said waveguides with respective high frequency waves having a relative phase difference, whereby a nonsymmetrical directivity pattern is produced.

15. High frequency antenna apparatus comprising a radiator having a pair of interconnected hollow waveguide sections angularly disposed with respect to one another, means for a1ternately exciting said' waveguide sections to produce partially overlapping directivity characteristics in space, said last-named means comprising a high frequency coupling disposed within each of said waveguide sections.

16. High frequency apparatus comprising an antenna having a pair of hollow wave guides at an inclined angle to one another, said wave guides having means distributed along the lengths thereof for electromagnetically coupling said wave guides to the surrounding space, respective coupling means coupled to said guides for exchange of electromagnetic energy therewith, circuit means to be coupled to said antenna, and means alternately coupling said circuit means to said respective coupling means.

WILLIAM W. HANSEN.

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

UNITED STATES PATENTS Number Name Date 2,002,181 Ilberg May 21, 1935 2,173,137 Sharma Sept. 19, 1939 2,189,549 Hershberger Feb. 6, 1940 2,206,923 Southworth July 9, 1940 2,241,119 Dallenbach May 6, 1941 2,259,124 Wendell Oct. 14, 1941 2,275,646 Peterson Mar. 10, 1942 2,279,031 Cockerell et a1. Apr. 7, 1942 OTHER REFERENCES Electronics," March, 1943, page 76.

Certificate of Correction Patent No. 2,500,178 March 14, 1950 WILLIAM W. HANSEN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 57, for the word moves read shows; column 6, lines 28 and 29,

strike out comprising variable imnected and insert instead employed 'in the line connected;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 27th day of June, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

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