US3046498A - Polarizer means - Google Patents

Description

July 24, 1962 F. J. GARDINER 3,046,498

POLARIZER MEANS Filed July 22, 1958 2 Sheets-Sheet l 1 w (3/ "I 9| E d 1 Y INVENTOR FRANK JGARDINER j BY zz Mfi ATTORNEYS July 24, 1962 F. J. GARDINER 3,046,498

POLARIZER MEANS Filed July 22, 1958 2 Sheets-Sheet 2 INVENTOR.

FRANK. J. GARDINER W QZU ATTORNEYS Unite 3,046,498 Patented July 24, 1962 3,046,498 POLARIZER MEANS Frank J. Gardiner," Bryn Mawr, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., 21 corporation of Pennsylvania Filed July 22, 1958, Ser. No. 750,196 2 Claims. (Cl. 333-21) The instant invention relates to means for selectively converting a linearly polarized electromagnetic wave to a circularly polarized electromagnetic wave.

Electromagnetic waves at microwave frequencies are usually transmitted through hollow conducting tubes known as wav guides. 1

It is often desirable to convert a linearly polarized wave to a circularly polarized wave. Heretofore, this has been accomplished by utilizing a section of wave guide known as a step twist which was physically rotated to create 45 polarization. Another prior art method for accomplishing the same result utilizes a ferrite rotator.

.The device of the instant invention achieves selective dual polarization by leading a linearly polarized wave into a circular guide which is capable of supporting multiple polarization. A plurality of dielectric pins are selectively insertable into the section of circular wave guide. The pins are inclined at an angle of 45 degrees with respect to a linearly polarized electromagnetic wave which enters the wave guide. Thus, the dielectric pins are positioned to slow down a component of the linearly polarized wave oriented parallel to the pins while not effecting a component of the wave oriented at right angles to the pins. The retarded component combines with the non-retarded component resulting. in a circularly polarized electromagnetic wave. Thus, by simply inserting and withdrawing the dielectric pins the output of the circular wave guide is either circularly polarized or linearly polarized.

The insertion and withdrawal of the dielectric pins is accomplished by means of a simple linear acting solenoid which is of considerably lower cost than the rotating actuator or motor required to operate the step twist and the ferrite rotator of the prior art device. Further, the circular wave guide section into which the dielectric pins are inserted is much more economical to produce than the step twist guide and the ferrite rotator.

Accordingly, a primary object of the instant invention is to provide a novel means whereby .a linearly polarized electromagnetic wave may be selectively converted to a circularly polarized electromagnetic wave.

Another object is to provide a dual polarizer device utilizing a dielectric pin means.

Still another object is to position the dielectric pin means at an inclination of 45 degrees with respect to the linearly polarized wave with the pins being movable along their own axes.

A further object is to utilize the dielectric pin means in pairs with the pins of each pair being spaced approximately one quarter wave length apart thereby causing mutual cancelling of the reflected waves.

These as well as other objects of the instant invention shall become readily apparent after reading the following description of the accompanying drawings in which:

FIGURE 1 is a side elevation illustrating my novel polarizing means interconnecting a section of rectangular wave guide and a radiating horn.

FIGURE 2 is a cross-section taken through line 2-2 of FIGURE 1 looking in the direction of the arrows 2-2.

FIGURE 3 is a cross-section taken through line 3-3 of FIGURE 1 looking in the direction of the arrows 3-3.

FIGURE 4 is a cross-section taken through line 4-4 of FIGURE 1 looking in the direction of the arrows 4-4.

FIGURE 5 is a cross-section taken through line 5-5 of FIGURE 4 looking in the direction of the arrows 5-5.

FIGURES 6 and 7 are vector diagrams representing, respectively, a linearly polarized electromagnetic wave and a circularly polarized electromagnetic wave.

Referring to the figures, polarizer means 10 is adapted to be connected between wave guide 11 and radiating horn 12. Wave guide 11 is utilized to transmit electromagnetic waves to radiating horn 12 which is constructed to match the impedance of wave guide 11 to the impedance of free space while at the same time producing a directive wave pattern. The electromagnetic wave radiated by horn 12 is directed toward a reflector (not shown) which reflects the wave in a predetermined pattern.

Polarizer means 10 comprises an elongated guide member 13 of square cross-section having a circular open ing 14 extending along the axis thereof. Wave guide 11 is a hollow rectangular member having a square flange 15 at the end thereof which is adjacent to end 16 of guide member 13 and oriented at an angle of 45 with respect to guide member 13. Screw means 17, passing through clearanc holes in flange 16, are received by threaded openings in guide member 13 to thereby secure wave guide 11 to polarizer means 10.

Horn 12 is provided with a square opening 18, in the bottom surface 19 thereof, which is positioned in alignment with circular opening 14 of guide member 13. Brackets 20 and 21 secured to side walls 22 and 23,. re spectively, of horn 12 are positioned adjacent to the end 24 of guide member 13. Fasteners 25, extending through clearance holes in brackets 20 and 21, are received by tapped holes in the end 24 of guide member 13 thereby securing horn 12 to polarizer means "10. Brace 99 extends from the apparatus fram 98 to rigidly secure polarizer 10 in place.

Polarized means 10 also includes a plurality of dielectric pins 31-34 which are longitudinally spaced along the length of guide member 13. Pins 31-34 are preferably constructed of silicone or Teflon fiber glass and ar affixed to insulating plate 35 having hollow guide members 36, 37 affixed thereto in alignment with openings 38, 39 respectively of plate 35.

Holes 41-44 extend from surface 40 of guide, member 13 to opening 14 and are positioned to receive'pins 31-34, respectively Guide studs 46 and 47 extend upwardly from surface 40 and are positioned to be received by the openings of guide members 36, 37, respectively. Coil springs 48 and 49, disposed about studs 46, 47, re spectively, bear against surface 40 of guide member 13 and the lower surface 50 of plate 35 thereby biasing pins 31-34 away from opening 14. Screw means 51 secures bracket 52 to plate 35 while screw 53 is entered through slot 54 of bracket 52 thereby securing bracket 52 to the shell 55 of solenoid 56.

Solenoid winding 57 and sleeve 58 are mounted internally of shell 55 and secured thereto. U-shaped member 59, which straddles bracket 60, and extends through an opening in plate 35, rigidly secures solenoid slug 61 to surface40 of guide member 13. Solenoid 56 and plate 35 are disposed within housing 62 which is secured to guide member 13 by means of Screws 63, 64. Leads 65, 66 of solenoid energizing winding 57 extend through opening 67 in the top of housing 62.

Springs 48 and 49 bias pins 31-34 to an upward position with respect to FIGURE 5 wherein pins 31-34 are not disposed within opening 14; Upon energization of solenoid winding 57, shell 55 will move downward until 3 the inner top surface 71 of shell 55 strikes the top 72 of slug 61. Since pins 31-34 are rigidly aflixed to She 55, pins 31-34 will be projected into opening 14 as indicated in phantom in FIGURE 5.

Vector E (FIGURE 6) is utilized to designate the electric field of a linearly polarized wave which is being transmitted through rectangular wave guide 11. Vector E may be broken into two components E and E, which are displaced in space by 90 degrees from one another but are in equal phase relationship.

Vectors E and B are each inclined at 45 degrees With respect to the walls of Wave guide 11. A circularly polarized electromagnetic wave is represented by two vectors E, and E displaced in space by 90 degrees and also out of phase by 90 degrees.

When pins 31-34 are disposed within opening 14 they extend approximately to the center thereof and are positioned parallel to the component of the linearly polarized electromagnetic wave represented by vector E thereby retarding this component. However, the component represented by vector E being positioned at right angles with respect to pins 31-34, will be unaflected thereby. The retardation of component E caused by the dielectric pins 31-34 will amount to approximately a 90 degree phase shift. Thus, vector E will now be displaced from vector E by 90 degrees in space and also 90 degrees in phase to produce a circularly polarized wave.

The presence of the first dielectric pin 31 encountered by the linearly polarized electromagnetic wave causes a partial reflection of the wave. This undesirable condition is overcome by the next positioning pin 32 a distance approximately a quarter wave length from pin 31. Thus, the reflection from pin 32 will be 180 degrees out of phase with respect to the reflection caused by pin 31 resulting in the cancellation of these reflections. Ideally, the spacing between 31 and 32 would be equal to a quarter Wave length. However, certain practical considerations reduce this distance to some figure slightly less than a quarter Wave length. In a similar manner, pins 33 and 34 are spaced apart a distance equal to slightly less than a quarter wave length.

Slot 54 of bracket 52 is elongated in order to provide an adjustment which will establish the extent of the penetration of dielectric pins 31-34 into opening 14 and guide member 13.

Thus, I have provided a novel means whereby a linearly polarized electromagnetic wave may be selectively converted to a circularly polarized electromagnetic wave.

Although I have here described preferred embodiments of my novel invention, many variations and modifications will now be apparent to those skilled in the art, and I therefore prefer to be limited, not by the specific disclosure herein, but only by the appending claims.

I claim:

1. A polarizer converter for converting linearly polarized electromagnetic waves of a predetermined frequency to corresponding circularly polarized Waves comprising a hollow wave guide member with cylindrical guide path, a plurality of pins of dielectric material insertable through individual spaced apertures into said guide member aligned longitudinally of the member on one side thereof and in 45 orientation to the input coupling direction thereto of the linearly polarized waves, said dielectric pins being proportioned to retard the phase of the component of the linearly polarized wave parallel thereto by substantially and to have no effect upon the phase of the wave component perpendicular thereto to thereby produce a corresponding circularly polarized wave transmitted to the guide member output, a solenoid mechanism operatively connected to said pins to selectively insert and retract them through said apertures in unison and effect corresponding passage to the guide member output of linearly and circularly polarized waves and an adjustable stop means to preset the amount of penetration of said pins into said guide so the same amount of penetration will occur for each insertion, said solenoid means comprising an energizable coil and a cooperating armature member, a plate secured to said armature for positioning and securing said dielectric pins; said plate being positioned transverse to said armature and having a pair of threaded apertures at opposite ends thereof; said adjustable stop means comprising first and second stop pins threadably engaged by said threaded apertures, said stop pins being adapted to abut the exterior of said waveguide when said dielectric pins are inserted through their associated apertures to adjust the amount of penetration of said dielectric pins; said stop pins being independently movable, said dielectric pins being secured to said plate at points along a line drawn between said threaded apertures.

2. A polarizer converter as claimed in claim 1, in which at least two of said dielectric pins are spaced apart substantially one-quarter wave length of the waves therethrough to inhibit wave reflection effects thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,530,979 Matland Nov. 21, 1950 2,668,191 Cohn Feb. 2, 1954 2,768,354 Hogan Oct. 23, 1956 2,775,741 Corbell Dec. 25, 1956 2,810,890 Klopfenstein Oct. 22, 1957 2,853,688 Leboutet Sept. 23, 1958 2,863,128 Gilchrist et al. Dec. 2, 1958 OTHER REFERENCES Microwave Transmission Circuits (Ragan), McGraw- Hill Book Co., New York (1948). (Page 373 relied on.)

Proceedings of the IRE, article by Simmons, vol. 40, issue 9, pp. 1089, 1090, September 1952.

Abstract of application, Serial Number 187,341, Vol. 671, Page 1498, O.G. June 1953.

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