US3316509A

US3316509A - Variable phase shifter

Info

Publication number: US3316509A
Application number: US282012A
Authority: US
Inventors: Donald R Ayer; Lowe W Ralph
Original assignee: Sanders Associates Inc
Current assignee: Lockheed Corp
Priority date: 1963-05-21
Filing date: 1963-05-21
Publication date: 1967-04-25
Anticipated expiration: 1984-04-25
Also published as: SE313858B

Description

D. R. AYER ET VARIABLE PHASE SHIFTER April 25; 1967 V 2 Sheets-Sheet 1 Filed May 21, 1963 FIGB INVENTORS. DONALD R. AYER W. RALPH B'l' ATTORNEY April 25; 1967 R, AYER ET AL 3,316,509

VARIABLE PHASE SHIFTER Filed May 21, 1963 2 Sheets-Sheet 2 b 45 78 40b 62 38 I i I I I 420 4O 42G f i 45 INVENTORS H2 DONALD R. AYER w. RA F l G. 8 BY LOWE ATTORNEY United States Patent 3,316,509 VARIABLE PHASE SHIFTER Donald R. Ayer and W. Ralph Lowe, Nashua, N.H., as-

signors to Sanders Associates, Inc., Nashua, N.H., a corporation of Delaware Filed May 21, 1963, Ser. No. 282,012 10 Claims. (Cl. 33331) This invention relates to an improved high frequency variable phase shifter and to an improved impedance matching device incorporating it. The phase shifter comprises a transmission line in which different insulators are longitudinally moved between inner and outer conductors to vary the velocity of propagation and, accordingly, to vary the phase delay imparted to signals propagating along the line. The phase shifter has no sliding inner conductor contacts and is sufiiciently compact for use in miniature high frequency circuits.

In general, a variable phase shifter is used to adjust the phase of a high frequency signal, or, in other words, to vary the time required for a signal to propagate between two points in a circuit. This can be accomplished by changing either the physical length of the transmission path between the two points or the velocity of propagation along the path. The velocity may be changed by varying the dielectric constant of the insulator between the transmission line inner and outer conductors. To obtain efiicient transfer of energy through a phase shifter, it is generally desirable that its characteristic impedance remain substantially unchanged when the phase delay through it is varied.

A common phase shifter used prior to the present invention is the line stretcher, a constant impedance transmission line constructed with telescoping conductors so that the physical length of the transmission path can be varied. However, the trombone construction of the inner conductor requires sliding contacts; which are unreliable and costly to construct. In addition, line stretchers are not suited for compact construction are thus relatively incompatible with present compact transmission line circuits incorporating strip transmission line or the like.

Accordingly, it is an object of the present invention to provide an improved phase shifter having a small size.

Another object is to provide a small, constant impedance phase shifter that is characterized by high reliability.

Still another object of the invention is to provide a compact phase shifter having relatively simple and low cost construction.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements and arrangements of parts which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view, partly broke away, of a phase shifter embodying the present invention,

FIG. 2 is a sectional view taken along line 22 of FIG. 1,

FIG. 3 is a top plan view, partly broken away, of another phase shifter embodying the invention.

A FIG. 4 is a sectional view taken along line 44 of FIG. 3,

FIG. 5 is a sectional view taken along line 5-5 of FIG. 3,

FIG. 6 is an enlarged view of a portion of FIG. 4,

FIG. 7 is a sectional view, partly broken away, of an impedance matching device embodying the present invention; this view is taken along line 7--7 of FIG. 8; and

FIG. 8 is a sectional view taken along line 88 of FIG. 7.

In general, the present phase shifter comprises a transmission line, having a fixed physical length, in which the dielectric material between the inner and outer conductors is continuously changeable. The velocity of propagation in the phase shifter and, correspondingly, the phase delay between its input and output ports, vary as the dielectric material is changed. The phase shifter has no movable inner conductor contacts, and accordingly, losses and impedance discontinuities are rendered substantially negligible so that reliable performance is achieved. Furthermore, it is compact, whether using coaxial or strip transmission line.

An improved impedance matching device utilizes the present phase shifter to adjust the electrical distance that an adjustable short circuited stub is spaced from an impedance element being matched. This device, which is compact, is particularly suited for construction with strip transmission line.

More specifically, referring to FIGS. 1 and 2, the phase shifter is preferably constructed with a conductor 10 provided with

vertical portions

10a and 10b supported in a lower housing 12. A horizontal conductor portion 10c, extending within a cavity 14 in an upper housing 16, links the

portions

10a and 10b. The

housings

12 and 16, made of electrical conducting material, such as aluminum or copper, form the outer conductors 17 of a transmission line of which conductor 10 is the inner conductor. A section 14a of the cavity 14 is partially filled with an insulator 18 having a high dielectric constant. Section 140, constituting the remainder of the cavity, may be filled with air, whose unity dielectric constant is substantially lower than-that of the insulator 18. The housing 16 is adapted to slide along the housing 12, in the directions indicated by the arrow 19, to change the length of the conductor portion 10c engaged by the insulator 18 and thereby change the phase delay imparted to signals propagating along the portion 100. The lower housing 12, preferably an elongated rectangular bar, is formed with

cylindrical apertures

20 and 22 that accommodate the

inner conductor portions

10a and 10b. Outer conductors 24a and 26a of coaxial connectors indicated generally at 2-4 and 26 are secured to the housing 12 and form extensions of the

apertures

20 and 22. Inner conductor 10, shown having a circular cross section and an over-all U-shape, is symmetrically, disposed within the

apertures

20 and 22 and the outer conductors 24a and 26a. The inner conductor can be supported with suitable dielectric supports such as pins or beads (not shown) according to well-known techniques.

Still referring to FIGS. 1 and 2, the upper housing 16 is machined to fit over the lower housing 12 and has runners 28 that slidably engage ways 30 on the housing 12 to guide the motion of the upper housing to the longitudinal direction. Electrical contact between the housings may be enhanced with spring contacts (not shown) or the like. I

As seen in FIG. 2, the cavity 14 preferably extends within the housing 16 for at least twice the length L of the conductor portion 10c. The insulator 18, made of polytetrafluroethylene (commercially available as Teflon) or polyethylene, for example, substantially fills the cavity section 14a for a length preferably slightly greater than L, leaving only a narrow space 14c (FIG. 2) to allow movement of the housing 16 and the insulator 18 along the inner conductor portion 100.

The characteristic impedance of a transmission line is an inverse function of the dielectric constant of the insulator between the conductors and a direct function of the inner conductor thickness.

3 interconductor spacing, or, more specifically, the spacing between the inner and outer conductors relative to the in the cavity section 14a is greater than in the section 14b, the interconductor spacing in portion 14a should be correspondingly larger than the spacing in section 14b, to maintain uniform impedance in both sections. This may be achieved by securing conducting

strips

32 and 34 to the housing 16, in the section 14b, to reduce the interconductor spacing. The insulator 18 and the

strips

32 and 34 have

tapered ends

18a, 32a and 34a, respectively, to provide a smooth electrical transition between the

cavity sections

14a and 14b.

Referring to FIG. l, the phase shifter may conveniently have a scale 35 engraved or stenciled on housing 12 and a pointer 36 secured to housing 16 to indicate the position of the upper housing relative to the lower housing. The operation of the phase shifter of FIGS. 1 and 2 may be considered by assuming, for the purpose of illustration, that connector 24 is an input port and connector 26 an output port. .Qualitatively, the velocity of propagation along the inner conductor portion 100 is smaller in the cavity section 14a than in the section 14b, where the insulation between the conductor and the outer con-- ductors has a smaller dielectric constant. Accordingly, when the housing 16 is moved to the right (FIG. 1) so that the cavity portion 14a engages a larger portion of the conductor portion 100, the phase delay of signals arriving at connector 26 increases with reference to the phase at the connector 24.

More specifically, assuming the length of the cavity 14 is at least equal to 2L (i.e., at least twice the length of conductor portion 10c), let

' d =length of section 1401 enclosing conductor portion 10c,

d =length of section 14b enclosing conductor portion 100,

e =dielectric constant of insulator 18,

e =dielectric constant of insulator (e.-g., air) in section 14a, where e e and t=free space wavelength at the operating frequency.

Neglecting the fixed phase delay in the non-varying portions of the phase shifter, the relative phase delay, in radians,yalong the conductor portion 100 is given by when d =L. V

The range of phase delay, termed dynamic phase delay, is given by,

The dynamic phase delay can thus be increased by in- V creasing the length of conductor portion 100 or by increasing the disparity between the dielectric constants e and e 7 The inner, conductor 10 of the phase shifter shown in FIGS. 1 and 2 can also be constructed with a strip line configuration, as used in the devices. described below.

Since the dielectric constant A dual phase shifter, in which the phase delays through two transmission lines indicated at 35 and 37 are simultaneously varied inversely with respect to each other, is shown in FIGS. 3 thru 6. The

lines

35 and 37, interconnecting

ports

48 and 50 and

ports

52 and 54, respectively, have

inner conductors

44 and 45, respectively. The dual phase shifter is constructed with a circular electrically conducting housing 38 having an internal annular cavity 40 (FIG. 4). A fiat outer ring 42, partially disposed within the cavity 40, supports an annular dielectric sheet 46 in a slot 42a (FIGS. 4 and 6). The sheet 46, in turn, carries the substantially semicircular strip transmission line inner conductors 4444 and the diametrically opposing conductor 45-45 on its inner edge.

. As best seen in FIGS. 4 and 5, cavity 40 has a narrow neck portion 40a that accommodates the ring 42 and an enlarged portion 40b in which the

conductors

44 and 45 are disposed. Suitably seated bearings 56-56 in the portion 40a rotatably support the housing 38 on the ring 42 so that the housing may be rotated withrespect to the ring. Insulators 58 and 60 (FIG. 4), secured to the housing 38 in the cavity portion 40b, extend around one half the circumference of the cavity. Conducting strips 62 and 64 are secured to the housing 38 in the other half of the cavity portion 40b. The strips 62 and 64 and the cavity-forming walls of the housing 38 are the outer conductors of the

transmission lines

35 and 37. The portion of the cavity 40 containing the

insulators

58 and 60 will be referred to as a delay section.

Since the dielectric constant of the

insulators

58 and 60 is larger than that of the air dielectric between the inner and outer conductors elsewhere in the transmission lines, the phase delays imparted to signals propagated in the delay section are larger than elsewhere in the lines. Accordingly, the phase delay between the

ports

48 and 50 is a maximum when the delay section fully engages the inner conductor 44. With the housing 38 rotated for this condition, the conductor 45 between the

ports

52 and 54, does not engage the

insulators

58 and 60, and, hence, a minimum delay is imparted to signals propagating between latter ports. Rotation of the housing 38 will now decrease the delay between the

ports

48 and 50 and increase the delay between the

ports

52 and 54, as the delay section encloses less of the conductor 44 and more of the conductor 45.

More specifically, the phase delays, in radians, along the transmission line

inner conductors

44 and 45, respectively, are:

as g twa-vanwzauo (7) and where r is the radius of the circular path along which the

conductors

44 and 45 are disposed,

k is the wavelength at the operating frequency,

0 is the angle between a reference line, indicated at 66 in FIG. 3, and one end of the transmission line delay section,

6 is the dielectric constant of the

insulators

58 and 60,

in the delay section,

5 is the dielectric constant of the interconductor insulator (air) in the rest of the cavity 40,

C is a constant, and

I The range of phase delay, AI the difference in the phase delay when 0=0 and when 6=1r, or (approximately) is given by The differential phase delay, or the difference in phase delay between the paired

ports

48 and 40, 52 and 54 for any value of 0, is given by The dual phase shifter is suited for automatic remote operation with a rotary actuator, such as an electric motor (not shown), coupled to the housing 38 by means of holes 6868 (FIGS. 3 and 4). The phase shifter may be supported, and ring 42 constrained from rotation when the housing is rotated, by fastening the ring 42 to a stationary base (not shown) with the aid of mounting holes 70-70 (FIG. 3).

With further reference to FIGS. 3 thru 6, the

inner conductors

44 and 45 are preferably made of metallic foil bonded to the dielectric sheet 46 according to standard strip transmission line techniques. The sheet 4 6 and ring 42 may be fabricated in semicircular sections oined together in the cavity 40, or the housing 38 may be formed from a pair of circular members fastened together with the sheet 46 and ring 42 between them. Wave- .guide-to-strip line transitions 7272, provided between each of the ports 48-54, and the inner conductors may take the form discussed on pages 4450 of the Handbook of T ri-Plate Components, Sanders Associates, Inc. (1956). The phase shifter can also be constructed with coaxial or strip transmission line connectors at the ports 48-54.

The conductors 62 and 64 (FIG. 5) reduce the interconductor spacing to maintain substantially uniform the characteristic impedance of the transmission lines in the delay section and in other parts thereof. In addition, the

insulators

58 and 60 and the conductors 62 and 64 are preferably formed with tapered ends, similar to the

ends

18a, 32c and 34a (FIGS. 1 and 2) to provide smooth transitions at the ends of the delay section. A scale, a portion of which is indicated in FIG. 3 at 74, may be provided on the ring 42, to coact with a pointer 76 secured to the housing 38 for indication of the position of the delay section of the line with respect to the reference line 66 (FIG. 3). Spring contacts 78-78 (FIGS. 4 and 5) are preferably provided between the inner edge of the ring 42 and the outer edge of the cavity portion 40b to provide reliable electrical contact between the ring 42 and the housing 38.

Referring now to FIGS. 7 and 8, the phase shifter may be incorporated in an impedance matching device having an open-circuited transmission line stub indicated generally at 80. The stub 80 is connected in parallel with a transmission line, indicated at 82, forming part of a phase shifter generally similar to a single phase shifter in the dual device of FIG. 3. Variation of the phase delay along the stub 80 changes the impedance presented by the stub to the line 82, and, in addition, adjustment of the phase shifter delay varies the electrical distance of the stub from one port of the matching device. Thus, the device provides an impedance whose phase and magnitude are variable over a wide range.

The impedance matching device has a base 84 with a metallic housing 86 rotatably supported on it by bearings 88. A central shaft 90 is supported on the base 84 with bearings 92 for rotation independent of the housing 86. Arms 94 extend radially from the shaft 90 to move a stub assembly, indicated at 96 and described below in greater detail, in a circular path along the stub 80 as the shaft 90 is rotated.

The housing 86, preferably formed with a lower section 86a andan upper section 86b, has a substantially annular interal cavity 98. As best seen in FIG. 8, the cavity has a plurality of concentric

annular regions

98b, 98c, 98d and 98e. The upper housing section is supported on the lower section by two post sections 860 and 86d (FIG. 7) that interrupt the annular region 98c.

A dielectric disk 100, disposed within the cavity 98,

carries strip transmission line

inner conductors

99 and 101 bonded to both sides in the

regions

98b and 98d form, respectively, the stub and the line 82. The surfaces of the housing 86 forming the walls of the

cavity regions

98b and 98d are the outer conductors for the stub 80 and the transmission line 82. As seen in FIG. 7, the inner conductor 101 of transmission line 82 extends in a generally semicircular path between two strip line-to-wave-guide adapters, generally indicated at 102 and 104, that include

flanged waveguides

106 and 108, respectively.

As best seen in FIG. 8, the

waveguides

106 and 108 are secured to the base 84 and support the dielectric disk in a fixed position with respect to base 84. The disk 100 is held in place by insulators 110 disposed between inner conductor 101 and the

waveguides

106 and 108. Additional support for the disk 100 may be provided by dielectric members (not shown) that are slidably mounted between the disk and the housing 86 or the stub control assembly 96.

Insulators 112 partially fill the cavity region 98d enclosing the conductor 101. More specifically, the insulators 112 occupy substantially one-half the circumference of the region 98d, while conducting members 114 partially fill the other half of the circumference of this region. The construction of the cavity region 98d, insulators 112, conducting members 114 and the transmission line 82, between the

flanged waveguides

104 and 106, is substantially similar to the like parts of the rotary phase shifter described above with reference to FIGS. 3 thru 6. Thus, it provides a variable phase delay between the fianged waveguides when the housing 86 is rotated with respect to the inner conductor 101. Similarly, rotation of the housing 86 with respect to conductor 101 changes the electrical distance between the stub and the flanged waveguide 106.

In addition, rotation of the shaft 90 moves the stub control assembly 96 to change the electrical distance between the junction 116 (FIG. 7) of the stub 80 with the line 82 and the open circuit at the other end of the stub. This, in turn, changes the impedance presented by the transmission line stub 80 to the line 82. For example, when the electrical spacing of the open circuit from the junction 116 is a quarter wavelength, the impedance presented by the stub 80 to the line 82 is, ideally, a short circuit, and when the spacing is a half wavelength, the impedance is ideally an open circuit. At interme diate spacings the impedance varies between these values according to well-known principles. Thus, by rotating the shaft 90 and the housing 86, the phase and magnitude of the impedance presented to waveguide 106 can be independently selected.

Still referring to FIGS. 7 and 8, the stub assembly 96 may be constructed as a toroid 120 of substantially rectangular cross section and having an annular slot 121 in its outer surface for receiving the disk 100 and con ductors 99 of stub 80.

As best seen in FIG. 8, the toroid 120 has a conductive cylindrical inner portion 120a. Half of the circumference of the toroid outer portion, forming the slot 121, is formed with conductive semicircular members 122, symmetrically disposed above and below the disk 100. Similarly disposed dielectric semicircular members 123 form the other half of the toroid outer portion.

The toroid 120 fits within the cavity region 98b of housing 86 and its portion 120a, and conductive members 122 are constructed to maintain low-reactance, sliding contact with the housing 86.

Rotation of shaft 90, revolving the entire stub assembly 96 to position the dielectric members 123 adjacent the full length of stub 80 inner conductor 99, provides maximum phase delay along the stub 80. Alternately, the assembly 96 can be rotated with respect to the disk 100 to position the conductive members 122 adjacent the full length of conductor 99 to provide minimum delay along 7 the stub. Thus, the stub .80 and the phase control assembly 96 operate to vary the phase delay between the junction 116 and the open circuited end of conductor 99 in the same manner as each phase shifter in the dual device of FIG. 3.

The impedance matching device may be constructed, in the manner described, to have a small size and yet provide a wide range of continuously adjustable complex impedances between the

waveguides

106 and 108. Thus, it is ideally suited for compensating for a wide range of impedance mismatches or, alternatively, for providing a desired mismatch. Because of its small size, the matching device is particularly suited for use with miniature high frequency circuits constructed with strip transmission line or even miniature, high frequency, waveguide.

It.should be noted that even though the transmission line sections in FIGS. 7 and 8 do not include extensive direct electrical connections between the upper and lower ground plane surfaces, radiation into and out of the stub 80 and transmission line 82 can be kept at negligible proportions. Specifically, if the

housing sections

86a and 86b are sufficiently close together at the

cavity portions

98c and 98e, and these portions are sufiiciently Wide, the capacitive reactance between the

sections

86a and 86b will be negligible at the frequency of operation. Operation will then take place as if there were direct electrical connections. Similarly, the capacitance between the toroid portion 120a and the

sections

86a and 86b 'minimizes imperfections in the sliding contacts between these members.

The same principles apply to the embodiments of FIGS. 1-6. In this connection, reference is made to U.S. Patent No. 2,926,317.

It should be noted that the variable lengthlines and the impedance matching device described herein may be used to advantage as the adjustable components in tunable filters. For example, givenresonate line lengths corresponding to inductive and capactive'reactances, they will resonate with and couple through capacitors incorporated in the strip transmission lines. A series capacitor may take the compact form shown on pages 93 and 102 of Handbook of Tri-Plate Microwave Components, N. Wild et al., published by Sanders Associates, Inc., in 1956. A parallel-connected capacitor may take the form of an enlargement of the widthof the center conductor of the transmission line.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efiiciently attained and, since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. A variable phase shifter for high frequency electric signals, said phase shifter comprising, in combination,

:a transmission line having an inner conductor disposed within an outer conductor system, said inner conductor being the central portion of a loop having end portions connected to said central portion and angularly disposed with respect thereto, one of said end portions serving as an input terminal of said transmission line and the other of said end portions serving as an output terminal of said transmission line, first and second insulators having different dielectric constants disposed within said trans- ,mission line between said inner conductor and said outer conductor system and in tandem with each other, and means for changing the relative lengths of said insulators disposed within said transmission line.

2. A variable phase shifter in accordance with claim 1 including means for moving said insulators longitudinally with respect to said inner conductor, the length of said inner conductor being less than the combined length of said insulators.

3. A variable phase shifter in accordance with claim 1, including means for maintaining the impedance of said transmission line substantially uniform when either of said first and second insulators is disposed therein.

4. .A variable phase shifter for high frequency electric signals, said phase shifter comprising, in combination, a transmission line having an inner conductor disposed within an outer conductor system, said inner conductor being the central portion of a loop having end portions connected to said central portion and angularly disposed with respect thereto, one of said end portions serving as an input terminal to said transmission line and the other of said end portions serving as an output terminal of said transmission line, an elongated composite insulator comprising first and second sections having ditferent dielectric constants and arranged in end-to-end relationship, means supporting said insulator for movement into and along said transmission line and between said inner conductor and said outer conductor system to inversely vary the length of said insulator sections disposed within said transmission line, so as to cause a variation in phase between the signals appearing on said input and output terminals.

5. The combination defined in claim 4 including a second transmission line connected in parallel with said first transmission line and having an inner conductor disposed within an outer conductor system, and means for varying the electrical length of said second transmission line.

6. A variable phase shifter for high frequency electric signals, said phase'shifter comprising, in combination, first and second elongated housing members fitted to gether for longitudinal movement relative to each other, said first member having a longitudinal recess opening on said second member, said second member having first and second apertures that communicate with said recess, said recess comprising first and second sections each of which extends along substantially one-half the length thereof, a transmission line inner conductor extending along said recess for substantially one-half the length thereof with its ends extending into said apertures, the recess walls provided by said housing members constituting transmission line outer conductors for said inner conductor, a first insulator of relatively high dielectric constant secured to said first member to occupy the space between said inner conductor and said outer conductors in said first section, a second insulator of relatively low dielectric constant occupying the space between said inner and outer conductors in said second section, whereby relative movement of said members changes the length of said first insulator between said inner conductor and said outer conductors to vary the time delay imparted to signals propagating along said inner conductor between said first and second apertures.

7. The combination defined in claim 6 in which the spacing of said outer conductors from said inner conductor is greater in said first section of said recess than in said second section thereof so that the impedance of said transmission line remains constant during relative movement of said members.

8. A high frequency rotary phase shifter comprising, in combination, housing means provided with an internal annular cavity having conducting walls, a dielectric disk disposed in said cavity and mounted for rotation therein with respect to said housing means, said cavity walls being the outer conductor for a strip transmission line that has a first strip line inner conductor secured to said disk along a substantially circular path whose length is less than that of a full circle, said first strip line inner conductor being the central portion of a loop having first and second end portions connected to said central portion and angularly disposed with respect thereto, said first and second end portions effectively serving as input and output terminals, respectively, of said first strip transmission line, first and second insulators having different dielectric constants and arranged end-to-end in a circular path substantially adjacent said inner conductor path, said insulators being disposed in said cavity so that when said disk is rotated with respect to said housing means the lengths of said first and second insulators between said inner conductor and said cavity walls vary inversely, thereby varying the time required for electric signals to propagate along said inner conductor.

9. The combination defined in claim 8 in which said housing means has an annular slot communicating with said cavity, said first strip line inner conductor being secured to a first semicircular portion of said disk, a second strip transmission line inner conductor secured to a second semicircular portion of said disk concentric with said first portion for movement along said first and second insulators when said disk is rotated with respect to said housing means, said second strip line inner conductor being the central portion of a loop having first and second end portions connected to said central portion and angularly disposed with respect thereto, said first and second end portions efiectively serving as input and output terminals, respectively, of said second strip transmission line, said end portions of said first and second strip transmission lines being connected to first and second pairs of transmission line connecting means, respectively, said connecting means being secured to said dielectric disk and being disposed outside of said cavity, said combination thereby providing a dual phase shifting action in which the phase delays imparted to signals propagating on said first and second inner conductors between said pairs of connecting means vary inversely as said housing means is rotated with respect to said dielectric disk.

10. The combination defined in claim 8 including a second strip transmission line inner conductor secured to said disk along a substantially circular path and connected at one end thereof to said first inner conductor, third and fourth insulators having diiferent dielectric constants and arranged end-to-end in a substantially circular path adjacent the path of said second inner conductor, said third and fourth insulators being disposed in said cavity for rotation with respect to said disk and said housing means to vary inversely the lengths of said third and fourth insulators between said second inner conductor and said cavity walls, thereby varying the time required for electric signals to propagate along said second inner conductor.

References Cited by the Examiner UNITED STATES PATENTS 2,454,530 11/1948 Tiley 333-31 3,017,587 1/1962 Kern et al. 333-31 3,092,793 6/1963 Augustine et a1. 33331 3,192,492 6/1965 Linder 33331 ELI LIEBERMAN, Primary Examiner.

Claims

1. A VARIABLE PHASE SHIFTER FOR HIGH FREQUENCY ELECTRIC SIGNALS, SAID PHASE SHIFTER COMPRISING, IN COMBINATION, A TRANSMISSION LINE HAVING AN INNER CONDUCTOR DISPOSED WITHIN AN OUTER CONDUCTOR SYSTEM, SAID INNER CONDUCTOR BEING THE CENTRAL PORTION OF A LOOP HAVING END PORTIONS CONNECTED TO SAID CENTRAL PORTION AND ANGULARLY DISPOSED WITH RESPECT THERETO, ONE OF SAID END PORTIONS SERVING AS AN INPUT TERMINAL OF SAID TRANSMISSION LINE AND THE OTHER OF SAID END PORTIONS SERVING AS AN OUTPUT TERMINAL OF SAID TRANSMISSION LINE, FIRST AND SECOND INSULATORS HAVING DIFFERENT DIELECTRIC CONSTANTS DISPOSED WITHIN SAID TRANSMISSION LINE BETWEEN SAID INNER CONDUCTOR AND SAID OUTER CONDUCTOR SYSTEM AND IN TANDEM WITH EACH OTHER, AND MEANS FOR CHANGING THE RELATIVE LENGTHS OF SAID INSULATORS DISPOSED WITHIN SAID TRANSMISSION LINE.