DE1114857B - Parametric microwave amplifier - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY
GERMAN / mmm> PATENT OFFICE

kl. 21 a ⁴ 29/50

INTERNAT. KL. H 03 f

EDITORIAL NOTE 1114857

H41227IXd / 21a *

REGISTRATION DATE: DECEMBER 15, 1960

NOTIFICATION OF THE REGISTRATION AND ISSUE OF THE
EDITORIAL; OCTOBER 12, 1961

The invention relates to parametric amplifiers for amplifying microwave energy.

Several types of parametric amplifiers have been developed to meet different requirements to meet the requirements of the particular system in which the amplifier is used should, and result from the surrounding conditions. One of the first to be successful in a microwave system Embodiments used consisted of all energy-propagating individual parts of coaxial Waveguides. In order to match the signal circuit, pump circuit and blind circuit of such an amplifier, provide coaxial line stretchers in three branches of the device. These voting units are quite suitable for tuning the device so that there is gain, but are the necessary steps are very time-consuming and do not correspond to the simple operation that is absolutely necessary in many institutions. In addition, the signal circle and the Pump circuit can tune independently of each other, but that a correction to the tuning of the Line stretcher in the blind circuit also changes the coordination of the signal circuit and the pump circuit.

The known coaxial amplifier mentioned also has numerous mechanical connection points, which can loosen during transport, which results in an upset of the various circles; however, this makes voting even more difficult. Furthermore, the many different complicate Components that such an amplifier has to manufacture other amplifiers with exactly the same Properties. Such amplifiers are therefore poorly suited for large-scale production Quantities.

The aim of the invention is to overcome the disadvantages outlined to avoid. In the parametric amplifier according to the invention, a piece of a rectangular waveguide is used with input end and short-circuit termination at the other end for the propagation of pump energy at a first frequency; a piece of a coaxial waveguide is attached to the side of an opening in the rectangular waveguide coupled at a point between the input end and the termination, runs transverse to the axis of the rectangular waveguide and is used to propagate signal energy in a second frequency that is lower than the first frequency. To the center conductor of the coaxial waveguide a non-linear reactance element is connected, which is the continuation of the center conductor the opening in the wall of the rectangular waveguide er parametric microwave amplifier

Applicant:

Hughes Aircraft Company, Culver City, Calif. (V. St. A.)

Representative: Dr.-Ing. G. Eichenberg

and Dipl.-Ing. H. Sauerland, patent attorneys,

Düsseldorf, Cecilienallee 76

Claimed priority: V. St. v. America of December 18, 1959 (No. 860 509/59)

Conrad E. Nelson, Gardena, CaHf.,

Harvey M. Endler, Santa Monica, Calif.,

and Kenneth M. Johnson, Los Angeles, Calif.

(V. St. Α.),
have been named as inventors

stretches, touches the wall of the waveguide opposite the opening and inside the rectangular waveguide just placed in a place where it is exposed to the strong magnetic field of the pump energy and runs parallel to the electric field of the pump energy, which is a mixture of the energy from the first frequency and the energy from the second frequency, with energy from one Difference frequency is formed and part of the pump energy is transferred to the signal energy. At the coaxial waveguide is transverse to its axis and at its outwardly facing end a coaxial one Attached tuning stub, by means of which the coaxial waveguide between the tuning stub and the reactance term is tunable to resonance at the second frequency. Between the voting stub and the reactance element is built into the coaxial waveguide, a low-pass filter that only Passes energy from the second frequency. In contrast, a high-pass filter is built into the rectangular waveguide, which is between the input end and the reactance term and only energy with the first Frequency passes.

The invention provides an easily tunable parametric amplifier with independent

109 708/264

other tunable pumping circuit and signal circuit, the tuning of both circuits practically not is influenced by corrections in the tuning of the blind circle. In addition, the Amplifier is characterized by its simplicity in construction and is therefore suitable for series production without the Properties of the individual devices deviate from one another in an impermissible manner.

The drawing illustrates an embodiment of the invention with two modifications. It shows

Fig. 1 is a perspective view of an amplifier with the features of the invention,

FIG. 2 shows a longitudinal section through the amplifier according to FIG.

Fig. 3 is a section along line 3-3 in Fig. 2 and

4 shows a detail from FIG. 2 with a modified attachment of the reactance element and a modified one Training of the blind circle.

1 shows a piece of a rectangular waveguide 11 with a normal coupling flange 12 for coupling a microwave pump energy source (not shown) of the high frequency f _p . From the flange 12, the waveguide initially extends with its normal or standard dimensions over a length 13. This is followed by a piece of length 17 in which the height of the waveguide, calculated across its broad side, gradually decreases. The remaining part of the waveguide 11 of length 16 again has a constant cross-section, but of a reduced height compared to the first piece 13. The tapering piece 17 enables a smooth transition from the standard height to the reduced height of the waveguide with a minimum of energy reflection. According to FIGS. 2 and 3, a movable short-circuit piston 18 is attached to terminate the waveguide 11 at the end of the waveguide section 16 which is reduced in height.

A piece of coaxial waveguide 19 is attached transversely to the longitudinal axis of rectangular waveguide 11 on a broad side of reduced height section 14 and contains a coaxial tuning stub 20 with movable short-circuit piston 21 which is attached transversely to coaxial conductor 19 at its outwardly facing end 22 . The outwardly pointing end 22 of the coaxial conductor 19 is connected to a structure (not shown) composed of a circulator and a signal energy source of the frequency / 1, where / _{s is} lower than f _p .

The coaxial conductor 19 joins the interior of the rectangular waveguide 11 at the connection point this via an opening 23 according to FIG. 2 in interaction. The opening 23 has its center the center line of the corresponding wide wall of the rectangular waveguide 11. The center conductor 24 of the coaxial conductor 19 stops shortly before the junction with the rectangular waveguide 11 and has at this Place an axial bore 26 for receiving a feed line 27 of a non-linear reactance element 28 and for making the electrical contact to this lead 27. The non-linear reactance element 28 is shown as a semiconductor diode which, as a continuation of the central conductor 24, extends through the opening 23 and extends transversely through the rectangular waveguide 11. The not shown second supply line of the non-linear reactance member 28 is suitably mounted in a holder 29 which is coaxial with the Center conductor 24 is aligned and itself by means of matching threads 31 in the holder 29 and in an opening 32 of the corresponding wide wall of the rectangular waveguide 11 is attached.

Pump energy introduced into the waveguide 11 by suitable coupling to the flange 12 hi propagates in this waveguide 11 in the TE ₀₁ fundamental wave type hi in the direction of the non-linear reactance element 28. Since the electrical field of the TE ₀₁ oscillation is greatest in the central plane of the rectangular waveguide 11 parallel to its narrow walls and the non-linear reactance element 28 is arranged in this same central plane, a strong magnetic field of the pump energy occurs in the reactance element 28, which makes the flow greater Currents in this member 28 results. The degree of coupling between the pump field and the member 28 is particularly good due to such a concentration of the current flow in connection with the reduction in the height of the rectangular waveguide 11 from its standard dimension in the region of the flange 12 to the reduced height 14 in the region of the non-linear reactance element 28.

By suitable coupling to the outwardly pointing end 22 of the coaxial conductor 19, signal energy fed into the latter is propagated in the coaxial conductor 19 as a TEM oscillation. Since the center conductor 24 is terminated by the non-linear reactance element 28 in the rectangular waveguide 11, the entire signal current flows through the reactance element 28. The degree of coupling between the signal energy and the non-linear reactance element 28 is particularly good as a result of this and through suitable adaptation between the coaxial conductor 19 and the reactance element 28. In the embodiment shown in the drawing, this adaptation is accomplished by tuning the signal circuit, which is indicated by the number 35 in FIG the opening 23 are diametrically opposite and are aligned transversely to the corresponding walls of the waveguide 11. By suitable setting of the piston 21 in the tuning stub 20, the piece 35 of the coaxial conductor 19 lying between this and the non-linear reactance element 28 can be tuned particularly precisely to resonance for the signal frequency f _s , which results in a further improvement in the degree of coupling between the signal energy and the reactance element .

After the signal energy of the frequency f _s and the pump energy of the frequency f "have both been impressed on the non-linear reactance element 28, the two energies mix in this element 28 to form sum and difference frequencies. By allowing the propagation of reactive energy from the difference frequency fb = f _p -f _s , where f _b is to be referred to as the reactive frequency, part of the pump energy is converted into signal energy of signal frequency / _s and such a phase position that it amplifies the signal energy fed in. In order to achieve this, a section 38 of the rectangular waveguide 11 between the non-linear reactance element 28 and the piston 18 is tuned to resonance for the blind frequency f _b by actuating a fine adjustment button 39 which can be seen in FIG can be changed in a conventional manner. The tuning of section 38 to resonance for the blind frequency f _b

allows the reactive energy to be maintained in the parametric amplifier system.

Since the pump frequency is higher than the signal frequency, the rectangular waveguide 11 is the Signal frequency beyond its critical frequency. The signal energy is therefore not from the waveguide 11 propagated. But this is equivalent to an isolation between the signal circuit of the coaxial conductor 19 and the blind circle of the waveguide 11, so that an adjustment of the tuning piston 18 in Blind circle is completely without influence on the coordination of the signal circuit. For the same or similar Reasons for the coordination of the signal circuit is also not done by devices for impedance matching disturbed in the connection, not shown, to the pump energy source, for example in the form of well-known inductive rods or capacitive screws for the purpose of improvement the coupling to the reactance member 28 may be present.

A low-pass filter 41 is installed in the coaxial conductor 19 between the connection point of the tuning stub 20 and the non-linear reactance element 28 so that the adjustment of the piston 21 belonging to the tuning stub 20 does not affect the tuning of the blind circuit and that of the pumping circuit. Such a low-pass filter 41, as shown in FIG. 2, can consist in a conventional manner of two conductive disks 42 fastened to the center conductor 24 at a certain distance from one another and with a dielectric collar attached between the disks and the inner wall of the outer conductor 43 are provided. The two-part low-pass filter 41 is _{in resonance for the signal frequency / s} and has a wide pass band on both sides of the signal frequency. Because of the difference in the frequencies, practically all of the energy oscillating with the pump frequency or dummy frequency in the waveguide 11 is reflected at the low-pass filter 41. You can therefore tune the pumping circuit and the blind circuit independently of the tuning of the signal circuit.

Another device for isolating the circles from one another is in the form of a high-pass filter 46 is provided in the rectangular waveguide 11 between the coupling flange 12 and the non-linear reactance element 28 is attached. Different structures can be used for such a high-pass filter use, such as an inductive opening, inductive rods or a section according to FIGS. 2 and 3 of the waveguide of reduced width, which is in resonance for the pump frequency. So by having a Block 47 of conductive material between the two broad sides of the waveguide 11 on one of its Attaches narrow sides, one prevents the reactive energy from going beyond the block 47 in the direction of propagate the source of pumping energy. That means at the same time that some arrangements for adaptation in the pumping circuit, taken in section 13 of waveguide 11 or beyond this section will remain without influence on the coordination of the blind circle.

So that small changes in the coordination of the blind circle are not detrimental to the optimum Coupling between the pump circuit and the non-linear reactance element 28 adjusted adjustment between Effect pumping circuit and reactance member, the length of the rectangular waveguide section 38 can be reduced while adjusting the electrical length of the section to be about 180 ° for is the blind frequency and about 270 ° for the pump frequency. If you have by means of the piston 18 If such electrical lengths are set, the effect is as if the blind circle cavity 38 represents one small resistance for the pump frequency in the area of the reactance element 28, which has the consequence that minor corrections to the setting of the piston 18 for the purpose of tuning the blind circle no or only an insignificant influence on the coupling of the pump energy to the reactance element to have.

In operation, the pump energy and the signal energy to the waveguide 11 and to the Coupled coaxial conductors 19 and plant themselves in these conductors in the form of the corresponding fundamental waves away. With a pumping frequency that is higher than the signal frequency, the two energies mixed in the non-linear reactance element 28, a difference or dummy frequency being formed. Energy that oscillates at this dummy frequency is passed through section 38 of rectangular waveguide 11 maintained, which has been set by means of the piston 18 to resonance for the reactive frequency is. By allowing the reactive energy to propagate, part of the pumping energy is by means of of the non-linear reactance element 28 converted so that an energy component of signal frequency which is in phase with the incident signal energy and thus becomes the signal energy adds that the gain results.

The two-part low-pass filter 41 is in resonance for the signal frequency and has a wide pass band, its Midpoint lies at the signal frequency. It lets the signal energy through, but blocks the reactive energy and the pump energy that would otherwise seep through the coaxial conductor 19. Through this the signal circuit cavity 35 is isolated from the pumping circuit and the dummy circuit, so that changes in the The coordination of the signal circuit has no influence on the pumping circuit or the blind circuit. The non-linear reactance element 28 closes the coaxial conductor 19 and the signal frequency is beyond, i.e. h .. below the critical frequency of the rectangular waveguide 11. The signal energy therefore remains limited to the coaxial conductor 19, and changes in position of the blind circle tuning piston 18 or in the adjustment circles for the pump energy remain without Influence on the signal circuits. Similarly, the section of rectangular waveguide 11 of FIG reduced width a high-pass filter 46 which allows the pump energy to pass through, but not the reactive energy. This therefore remains limited to the cavity 38, and changes in the adaptation for the Pump energy that takes place in or in front of the waveguide section 13 has no effect on the blind circuit. The length of the blind circle cavity 38 is adjusted by means of the piston 18 so that this is an electrical Length gets that for the pump energy as weak impedance in the range of the nonlinear Reactance member 28 affects. This leaves minor changes in the coordination of the blind circle without influence on the quality of the coupling of the pump energy to the non-linear reactance element 28. A separation of the incident signal energy from the reflected amplified signal energy can then in a simple manner through the coupling

Claims (1)

7 8 In the example described, the end 22 of the coaxial conductor 19 faces the outside and is an amplifier for operation in the S and Z bands. happen. But with the same structure and the same structure and mode of operation of this description-like mode of operation, amplifiers can also be built for the implementation of corresponding sales operating in the S-band at lower frequencies Operation in lower frequencies with non-linear reactance element 28, the following characteristic bands define the desired values for the gain, graphical data: the bandwidth and the noise figure are easier to determine Signal frequency 2 800 MHz f ^ J * T * Γ ^ ^technis , ^che Pump frequency 11100 MHz ^{10 d} ^, ^high . *? ^F ^ ^u f ^{z e} ff ^ben ·. Z ₃ ^F f? stronger according to the invention it has been possible to use the w λΗΓΊ? Ληη MtL ^the relatively high frequencies of the 5-band Bhnd frequency 8 300 MHz X-band resulting problems so far Noise figure 2db _v . , ". ,,. ,, ...,. _o "... , ,, Gain 16 db loose that the amplifiers are in large numbers Bandwidth 25 MHz ^{15 nerste} ^ ^{en and s} i ° ⁿ nevertheless the given characteristics ., .., * V ^- . ' _onn im, have data adhered to for all pieces in a series. Tunability 2Ul) MHz ". ,. .,. ,. ~. ,. . . As for the vote, it was an example A similar amplifier working in the Z-band is shown in the amplifier for the X-band, its had the following characteristic data: Characteristic data were given above, possible, internal ο οπή A / itr, ²⁰ half of the specified range of 200 MHz for the S5;: · :::::::::: ι «SS Ab — a ^ t _to ^ w _ert ^^ _{νοη we} ni- Pumping power 75 mW § he to vote ^{as a Mmute.} Blind frequency 8 300MHz Gain 15 db PATENT CLAIMS: Bandwidth 5 MHz ^25th , _n . , .... "... _t Noise figure 5 db ^1- parametric microwave amplifier, characterized by a rectangular waveguide (11) If the bandwidth for the output signal is to be increased for the propagation of pump energy, the first frequency (J _p ) with an input end (12) can be modified according to FIG. 18) at the other allows a larger bandwidth, which in turn gives one end, a coaxial waveguide (19), which results in a larger signal bandwidth. In order to extend this to an opening (23) of the waveguide (11), a part of the blind circle cavity is left between the input (12) and the closure space 38, namely the one coupled to the non-linear reactor (18) is, transversely to the waveguide (11) dance member 28 adjoining part on which the reduction 35 runs and for the propagation of signal energy th height 14 and then expands the cavity 38 at a second frequency (J _s ) which is lower via a step 52 the greater height 54. That is than the first frequency (/ "), a at the central section 53 of greater height 54 extends to conductor (24) of the coaxial waveguide (19) to piston 18. As from the explanations given above - Closed non-linear reactance element (28), arguments about the influence of a reduction in the 40 which emerges as a continuation of the central conductor (24) height of the rectangular waveguide 11, has the through the opening (23) in the wall of the hollow-enlargement of the height of the waveguide 11 to le iters (11) extends, which the opening (23) counter-consequence that a smaller enlargement of the overlying waveguide wall touches and results in internal reactance with increasing frequency, which leads to half of the waveguide (11) at one point at a larger bandwidth. If one makes now the 45 introduced where it for the purpose of mixing of the energy of the two parts 51 and 53 of the dummy circuit cavity 38 of the first frequency (J _p) and the energy of the in Fig. 4 substantially equal length, each part at the second frequency (J ₅ ) the strong magnetic field of the reactive frequency is exposed to an electrical length of 90 ° of the pump energy and has parallel to the, so the enlarged part 53 represents a high Im- electric field of the pump energy, wopedance for the part 51 of a lower height With energy of a difference frequency (J ₆ ) there is a further reduction in the rise of the forms and part of the pump energy is transferred to the reactance with increasing frequency and signal energy, one at the after leads accordingly to an increase in the end of the band pointing outwards coaxial wave width, conductor (19) transversely attached to this coaxial Some semiconductor diodes can be used as non-linear 55 tuning stub (20) to tune the Rea Use dance members 28 without the need for a coaxial waveguide (19) between the Ab bias potential. However, other diodes tuning stub line (20) and the reactance element need a bias voltage, and for them (28) at resonance at the second frequency, the modified embodiment according to FIG. 4 can be used between the tuning stub line (20) and. There the holder 29 is fastened by means of a force 60 to the reactance element (28) in the coaxial shaft 56 made of insulating material, the low-pass filter (41) arranged in an opening (19) and attached to only 32 of the rectangular waveguide 11. An energy of the second frequency (J _s ) lets through, a bias voltage source, for example in the form of a battery 57, and one between the input (12) and the reactance element (28) in the waveguide (11) via a feed line passed through the holder 29 -58 to the end of the 65th high-pass filter (46) enclosed in the holder 29, which only allows energy from the non-linear reactance element to pass through during the first frequency (J _p ),
it via a second supply line 59 with the wall of the second amplifier according to claim 1, characterized ge-rectangular waveguide 11 is connected. indicates that the non-linear reactance term (28) consists of a semiconductor diode with a non-linear capacitance characteristic. 3. Amplifier according to claim 2, characterized in that the diode (28) transversely to walls of the rectangular waveguide is arranged between them and through a first supply line (27) is connected to the central conductor (24) of the coaxial waveguide (19) and in one Holder (29) sits, which can be screwed into a wall of the waveguide and for fastening a second lead for the diode is used. 4. Amplifier according to claim 2 or 3, characterized in that to achieve this as possible good electromagnetic coupling of the energies from the first and from the second frequency in the neighborhood of the diode (28) inductive iris 10 elements (36) are attached to locations within the rectangular waveguide (11) that are related on the opening (23) diametrically opposite and across the walls of the waveguide (11) are aligned. 5. An amplifier according to claim 1, characterized in that, to increase the bandwidth, a section of the waveguide (11) of reduced height is adjacent to a section (53) adjoining the short-circuit termination (18), the two sections at the difference frequency (f _b ) have the same electrical length of 90 °. 6. Amplifier according to claim 1, characterized in that the short-circuit termination (18) is a movable short-circuit piston. 1 sheet of drawings