US3072850A

US3072850A - Waveguide hybrid junctions

Info

Publication number: US3072850A
Application number: US38855A
Authority: US
Inventors: Richard M Whitehorn
Original assignee: Varian Associates Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1959-12-28
Filing date: 1960-06-27
Publication date: 1963-01-08
Anticipated expiration: 1980-01-08
Also published as: GB956728A; DE1286161B; US3066290A; CH405443A

Description

Jan. 8, 1963 R. M. WHITEHORN WAVEGUIDE HYBRID JUNCTIONS Filed June 2'7, 1960 Fig.2

IN V EN TOR. flown A1 W s #910712 iifiil ifi h Patented Jean. 8, ll5

3,972,859 WAVEGUEE HYBRID EUNQ'TEGNS Richard M. Whitehorn, Menlo Farls, Caiif assigns: to Varian Associates, Pain Alto, Calii, a corporation of California Filed June 27, 1960, Ser. No. 38,355 9 Claims. (U. 325446) units of minimum size and weight are desired.

it is the principal object of the present invention to provide a compact and light-weight hybrid junction possessing requency insensitive balanced properties.

One feature of the present invention is the provision Of a balanced hybrid junction comprising a waveguide capable of propagating in two orthogonal modes and adapted to accommodate a first polarized wave through one end thereof and a second perpendicularly polarized wave through a portion of waveguide surface adjacent said one end.

Another feature of the present invention is the provision of a balanced junction according to the previous paragraph, wherein a collinear pair of crystal rectifie-rs is interiorly inserted through said waveguide in the direction of polarization of said first wave to provide a balanced microwave mixer.

Still another feature of the present invention is the provision of a mixer assembly comprising a mixer in accordance with the preceding paragraph in combination with a crystal protector tube secured at said one end of said waveguide and a refiex klystron oscillator secured at said waveguide surface portion.

These and other features and advantages of the present invention will be more apparent upon a perusal of the following specification taken in connection with the accompanying drawings, wherein:

FIG. 1 is an isometric view of a microwave mixer assembly in accordance with the present invention,

PEG. 2 is a cross-sectional view taken along line 22 in FIG. 1, and

' FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2.

In the mixer assembly of FIG. 1, a section of rectangular waveguide 1 is mounted on a base plate 2 and sup ports the rear window of a commercially available crystal protector tube 3-for example, model MA34OA manufactured by Microwave Associates, Inc., of Burlington,

Massachusettsby means of a flange 4 at the front end of the waveguide section 1. The front window of the crystals protector tube 3 is centered in an opening 5 formed in the mounting flange 5 which is brazed to the front end of the base plate 2 and is adapted to receive energy'through an abutting choke flange (not shown).

Secured to the bottom of Waveguide section 1 is a commercially available reflex klystron local oscillator 6,

a for example, model VA-2l7S manufactured by Varian Associates at Palo Alto, California, with an operating frequency range of 8.5 to 9.6 kmc. As best seen in FIG. 3, the output cavity resonator 7 of tube 6 is coupled to waveguide section 1 via a longitudinally extending iris 8 formed in the base plate 2, the amount of power coupled through said iris being controlled by an attenuator card 9 slideably engaged in a slot milled through the underside surface of the plate 2. The tube 6 is tuned by means of a tuning plunger 10 slideably inserted in the output cavity 7 and actuated by the rotation of an externally threaded tuning knob ll. Spur gear 12 which controls the setting of potentiometer 12 is mated to the external threads of knob 11 so that the repeller electrode voltage of tube 6 determined by potentiometer 12 is adjusted to correspond with the setting of the tuning plunger 1%. A small screw 13 extends through tube mating flange '7 to provide a factory adjustment of the tuning range of the klystron.

A pair of crystal rectifiers 143 vertically extending through waveguide section 1 are secured under tension at the oppositely poled inward terminals thereof by split cylindrical conductor 15. The exterior terminal of each rectifier is secured under tension by a hat connector 16 mounted in insulated relation with respect to the waveguide section 1. p

- The DC. current in the crystals 14 is monitored by means of the voltage appearing at monitoring lugs 19 attached to each hat connector 16 thereby providing a check on the coupling of energy from the local oscillator to the crystals and permitting the attenuator card 9 to be positioned so that the current is within a range of optimum crystal performance. Resistor 17, connected between monitoring lug l9 and ground lug 2% attached to waveguide it, provides a DC. path to ground across which is established the current measuring voltage applied to terminal 19, and is chosen to establish a minimum bias across the crystals consistent with the requirements of the voltage measuring instrument. The DC. crystal current components which would produce undesirable leakage fields are filtered from terminals 19 by means of the shunt capacitor 18 connected in parallel terminals 19 by means of the shunt capacitor 18 connected in parallel with resistor 17.

The outwardly extending rearward flange 15' of conductor i5 is secured via a thin mica insulating sheet 21 to a partition 22 of the waveguide l and is contacted by screw 23 threadably inserted therein through phenolic insulating shoulder Washer 24 seated in an opening of partition 22. The screw 23 secures lug 25 to provide an output LP. terminal which is protected by means of a cement casing 25.

Also disposed within the waveguide ll are a dielectric partition 27 spaced rearwardly of the crystal protector tube 3 to provide an input impedance transformer, and a dissipative fin 23 as of rnetallized epoxy Piberglas projecting inwardly of the waveguide wall along the perpendicular bisector of the axes of crystal rectifier l4 and extending between partitions 2'7 and flange 15 as indicated by the phantom lines in H6. 2.

in operation, a vertically polarized signal wave is transmitted through the crystal protector tube 3 undisturbed by fin 2d and provides electric fields extending in the same direction along the responsive axis of each crystal rectifier 14. A horizontally polarized local oscillator wave is transmitted through iris 8 and is perturbed by the fin 2% so that electric fields of opposite direction are produced along the axes of the crystal rectifiers 14.

Since the relative phases between the local oscillator wave and the signal wave in the separate crystals are reversed, the LP. beat frequency component of the cur rent in the separate crystals are out-of-phase, whereas the relative phases between the local oscillator wave and the noise due to local oscillator fluctuations are the same. Thus, local oscillator noise is balanced out of the difference in the crystal currents which flows along conductors l5 and 23 to LP. terminal 25. The high frequency signal and local oscillator components are bypassed to ground through the capacitance between conaeraseo ductors 23 and conductor 22 thereby providing a frequency insensitive, balanced output at terminal 25.

Several advantageous features are to be noted with respect to the configuration of waveguide connections illustrated in FIG. 1. Both wave energy sources may be concentrated at one end of the waveguide for simplicity of access. The two input connections are of the same relative position and polarity as in the conventional magic- T junction, so that a-minimum of modifiication in the design of existing waveguide assemblies is necessary. Still further, the total energy input to the crystal rectifiers is fromone side only, thereby allowing considerable freedom in the mounting of the crystals; for example,

crystals designed for extremely high frequencies which are housed in a mounting that is large in relation to the Waveguide size, and which may incorporate a shorting plane on one side, may be used.

It should be further noted that the electromagnetic energy propagated axially down waveguide 1 is established in two orthogonal modes, one corresponding to each input signal, and that the modes are perturbedso that the electric fields of both modes are asymmetrical about all equipotentials of one mode but symmetrical about an equipotential of the other mode. As explained in greater detail inv my copending US. patent application, Serial No. 862,356, filed December 28, 1959 now US. Patent 3,666,296, issued November 27, 1962, such a mode pattern establishes a first waveguide region in which a directional component of the electric fields of the two modes will be in-phase and a second waveguide region in which the electric field of the two modes will be out-of-phase. Thus, balanced hybrid junctions having a variety of well-known applications are possible by providing appropriate connections directionally responsive to the electric fields in these regions, directly or by means of concomitant magnetic fields. Such connections may include, for example: a single mode waveguide, or a crystal rectifier (as in the illustrative example), capacitor, absorber or other device inserted directly into the waveguide. The described mode pattern permits the connections to be collinearly disposed and is therefore adaptable to simple and practical manufacturing techniques.

Various alternative techniques are available for establishing the desired asymmetrical orthogonal mode pattern including, for example, the use of a metallic projcction extending from the waveguide Wall, or an asymmetrical wave source coupling. Still further, alternative wa eguide cross-sectional configurations capable of supporting orthogonal modes, including, for example, a circular cross section, may be used.

Since many changes could be made in the above construction and many apparently widely difierent embodiment of this invention could be made without departing from the scope thereof, 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.

What is claimed is:

1. A balanced hyb id junction comprising a waveguide capable of axially propagating in two orthogonal modes, means located at one end of said waveguide for accommodating a first electromagnetic wave propagating in one of said modes, means located on the surface of said waveguide adjacent said one end for accommodating a second electromagnetic wave propagating in the other of said modes, a pair of connections spaced from said one end of said waveguide and directionally responsive to the electric fields of said modes, and means for perturbing said modes to produce electric fields of opposite direction in each connection with one mode and electric fields of the same direction in each connection-with the other mode.

2. A balanced microwave mixer comprising a section of waveguide capable of axially propagating in two orthogonal modes, means located at one end of said waveguide scction for accommodating a first electromagnetic wave propagating in one of said modes, means located on the surface of said waveguide adjacent said one end for accommodating a second electromagnetic wave propagating in the other of said modes, a pair of crystal rectifiers extending inwardly of said waveguide at a position remote from said one end, means for perturbing the electric fields in said waveguide to establish electric fields of opposite direction in each crystal rectifier with one mode and electric fields of the same direction in each crystal rectifier with the other mode, and means for combining the signals in said crystal rectifier to produce a balanced beat frequency output.

3. A balanced microwave mixer according to claim 2 wherein the inwardly extending terminals of said crystal rectifiers are of opposite polarity, and further including an output connector receiving said inwardly extending terminals.

4. A balanced microwave mixer according to claim 3 wherein said crystal rectifiers are collinearly disposed in the polarization direction of said first electromagnetic wave. 7

5. A microwave according to claim 4 further including means capacitively coupling said output connector to said waveguide section for bypassing the high frequency components of said first and second electromagnetic waves.

6. The combination of claim 4 further comprising a crystal protector tube secured to said one end of said waveguide section and a reflex klystron local oscillator tube secured to said adjacent waveguide surface.

7. The combination of claim 5 wherein the exterior terminals of said crystal rectifiers are insulated from said waveguide section, and further including a resistor connected between said exterior terminals and said waveguide across which is developed a DC. crystal current monitoring voltage and a capacitor connected in parallel with said resistor for bypassing A.C. current components.

8. The combination of claim 5 wherein said perturbing means comprises a dissipative fin projectinginwardly of the wall of said waveguide along the perpendicular bisector of the axes of said crystal rectifiers.

9. The combination of claim 8 furtherfincluding a partition at the end of the waveguide opposite to said one end, and wherein said output connector includes a conductor extending through said partition in insulated relation therewith.

References Cited in the file of this patent UNITED STATES PATENTS 2,547,378 Dicke Apr. 3, 1951 2,679,582 Edwards May 25, 1954 2,810,984 Blitz Oct. 22, 1957 2,813,972 Anderson et al Nov. 19, 1957 2,832,885 Brett Apr. 29, 1958 2,859,626 Tomiyasu Sept. 2, 1958 2,863,042 Sanders et al Dec. 2, 1958 OTHER REFERENCES Corbell: Microwave Mixer for Airborne Radar, Electronics, pages -71, FebruaryS, 1960.

UNITED STATES PATENT OFFICE TIETTTCATE GT 'EQTQN January 8 1963 Patent N00 3 012 850 Richard M, Whitehorn It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowa Column l line 60 after "receive" insert wave eolumn 2 line 31 v for D061, read A000 3 lines 35 and :36 strike out terminals 19 by means of the shunt capacitor 18 eonnented in parallel"; column 41 line 29 after; "microwave" insert We mixer e Signed and sealed this 10th day of September 1963,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Ufficer DAVID L. LADD Commissioner of Patents UNITED STATES PATENT oTTTcE TIERHHQATE GE QQRREGHQN Patent N00 3 012 850 January 8 1963 Richard M, Whitehorn It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowa Column l line 60 after "receive" insert wave eolumn 2 line 31 v for D061, read A000 3 lines 35 and :36 strike out terminals 19 by means of the shunt capacitor 18 aonnented in parallel"; column 41 line 29 after; "microwave" insert We mixer e Signed and sealed this 10th day of September 1963,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Ufficer DAVID L. LADD Commissioner of Patents UNITED STATES PATENT OFFICE @EREFCATE l QORRECTION Patent No, 3 OT2 85O January 8 1963 Richard M Whitehorn It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowa Column 1 line 6O after "receive" insert W wave column 2 line 31 for "DQCQ'" read ADC}, lines 35 and 36 strike out terminals 19 by means of the shunt oapaoitor l8 commented in parallel; column 4 line 29 afters microw ave" insert mixer e Signed and sealed this 10th day of September 1963.,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents

Claims

1. A BALANCED HYBRID JUNCTION COMPRISING A WAVEGUIDE CAPABLE OF AXIALLY PROPAGATING IN TWO ORTHOGONAL MODES, MEANS LOCATED AT ONE END OF SAID WAVEGUIDE FOR ACCOMMODATING A FIRST ELECTROMAGNETIC WAVE PROPAGATING IN ONE OF SAID MODES, MEANS LOCATED ON THE SURFACE OF SAID WAVEGUIDE ADJACENT SAID ONE END FOR ACCOMMODATING A SECOND ELECTROMAGNETIC WAVE PROPAGATING IN THE OTHER OF SAID MODES, A PAIR OF CONNECTIONS SPACED FROM SAID ONE END OF SAID WAVEGUIDE AND DIRECTIONALLY RESPONSIVE TO THE ELECTRIC FIELDS OF SAID MODES, AND MEANS FOR PERTURBING SAID MODES TO PRODUCE ELECTRIC FIELDS OF OPPOSITE DIRECTION IN EACH CONNECTION WITH ONE MODE AND ELECTRIC FIELDS OF THE SAME DIRECTION IN EACH CONNECTION WITH THE OTHER MODE.