TW515225B - Active radio frequency cavity amplifier - Google Patents

Abstract

An active radio frequency cavity amplifier (ARFCA) is provided having a housing defining an input cavity and an output cavity; a plurality of transistors mounted to said housing, each of the plurality of transistors having an input lead and an output lead; a first RF power coupling mechanism disposed within the housing in proximity to the input cavity for coupling RF power from a source into the input cavity to generate an RF field; a first conducting assembly having a plurality of conductors each configured to contact a respective input lead of each of the plurality of transistors for coupling the RF field in the input cavity to the input leads of the plurality of transistors; a second conducting assembly having a plurality of conductors each configured to contact a respective output lead of the plurality of transistors for coupling the amplified RF power from the output leads of the plurality of transistors to the output cavity; and a second RF power coupling mechanism disposed within the housing in proximity to the output cavity for coupling amplified RF power from the output cavity to a load.

Description

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Priority, this application claims that the name filed with the US Patent and Trademark Office on December 13, 200, is "Active RF Cavity Amplifier." The priority of the application, the serial number assigned in this case is 60 / 255,276, which is incorporated herein. The application is for reference. BACKGROUND OF THE INVENTION 1. The invention relates to a radio-frequency electromagnetic field resonance cavity. In other words, it relates to those who achieve high RF power output in these cavities. 2. The relevant process description is well known to everyone A high-frequency electromagnetic field is generated in the cavity to accelerate the charged particle beam in a radio-frequency accelerator such as a linear accelerator. In a typical linear accelerator structure, the RF power and power are provided by a vacuum tube amplifier operating at high voltage (tens of thousands of volts). The amplified RF power is transmitted from the RF vacuum official to the 2 cavity using a coaxial cable and the like. An oscillating electromagnetic field is formed in the cavity. A common linear accelerator such as a drift vacuum tube linear accelerator contains a series of drift vacuum tubes, which are arranged in the cavity to remove particles by an electric field Accelerate to form the desired particle beam. There are several applications or potential applications that require lighter and more transportable RF Cavity or linear accelerator. These applications include applications based on Earth orbit, decentralized on-demand medical isotope production, and high-power RF amplifiers. However, the necessary RF true 2 tubes, pressure power supply, power conditioning equipment and The weight and size of related components and other components constitute a considerable obstacle to the use of RF cavities or linear accelerators for these purposes. The solution to overcome the shortcomings of the RF S cavity mentioned above is shown in the United States No. 5,497,050, in the patent case map *, it is reproduced as _r4- This paper size applies to China National Standard (CNS) A4 (210 x 297 mm)

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Figure 1 containing this application shows the RF cavity (no) defined by the wall (112), "with a private inner surface (i 丨 4). The wall (1 12) is divided into two upper and lower cylindrical portions (120 ) And (122), and a solid state power amplifier module (126) of a ring array (124) is installed between the two parts. Each module (126) has an input terminal connected to a low-power RF excitation signal source. The negative DC terminal (140) is connected to the outer surface of the upper part (120), and the negative DC terminal (146) is also connected to the lower part (122) through a quarter-wave choke contact. When used as an amplifier, the RF cavity is (110) Contains a waveguide (160) or a coaxial cable output connector to guide high-power electromagnetic waves from the cavity (11).

In the right operation, the RF excitation input power applied to the terminal of the amplifier module (126) has a frequency corresponding to the required resonance mode of the cavity (110). Under the control of input and excitation, the amplifier module (126) induces a large RF current, and its threshold value flows at thousands of amps on the inner surface (114) of the wall (112) to establish the desired amplitude of the electromagnetic field. Due to the skin effect, this current flows through the inner surface of the cavity wall to a depth of only a few microns. The direct current through the module flows through most of the wall (ιΐ2). The amplifier with low impedance can only operate at high current and low voltage (126), and the particle beam generated along the axis of the cavity (110) operates at high voltage and low current, representing a high impedance load. Therefore, the RF cavity (11) is now functioning as a power combiner and matching transformer that is amplified into a module (126). The module (126) has a simple structure and requires very little packaging. The wall (112) of the edge cavity (10) is used for heat dissipation of the transistor. The overall cooling budget of the system has not been increased, and the most important part of the RF power system of the transistor is eliminated. At the same time, because the vacuum tube 2 required by the traditional RF linear accelerator is not necessary for the accelerator cavity (110), it also avoids the earth's high and medium-duty; -5- 515225 A7 B7 V. Description of the invention (3) The problem of failure. In particular, the power supply of the cavity (110) eliminates the RF power transmission loss of traditional accelerators, thereby achieving higher efficiency. The cavity published in U.S. Patent No. 5,497,050 is used as a linear accelerator, and its efficiency is relatively high, and the structure of the amplifier is still lacking in terms of effective operation. First, the cavity only shows the waveguide of the cavity output port, but it does not mention the input port that receives the RF power to be amplified. Second, for RF devices that involve resonant cavities, they must have a frequency tuning function that starts with phosphorus at the desired frequency. Therefore, the previous RF cavity in this patent neither describes nor shows the method of tuning required by the amplifier. SUMMARY OF THE INVENTION The object of the present invention is to provide a high-power RF cavity which can be easily converted into an efficient high-power amplifier. Another object of the present invention is to provide a high-power amplifier with discrete input and output ports. Another object of the present invention is to provide a high power amplifier having a frequency tuning capability. According to the present invention, the above objects are achieved by providing an active radio frequency cavity amplifier. This amplifier contains a housing that defines two independently tuned resonant cavities. Each cavity is generally cylindrical and contains a conductive wall. The first cavity, that is, the conductive structure of the input cavity, couples the RF field in the input cavity to the output leads of multiple power transistors. The input cavity contains a plunger assembly that couples low RF power from its source into the input S cavity. The output cavity also contains a plunger assembly that couples the amplified RF power to an external load. The plunger combination of each cavity is used to tune the cavity to _- 6 -_ This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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k 515225 A7 B7 V. Description of the invention (4) The device whose resonance frequency is required to work. The active radio frequency cavity amplifier of the present invention is a relatively light device and uses a low-voltage DC power source to supply radio frequency power transistors. The function of the input cavity is a power splitter and matching transformer for multiple RF power transistors. The output cavity is used as a power combiner and matching transformer for transistor output. The cavity wall can be used as a radiator for high efficiency. According to one aspect of the present invention, the combination of the transistors in the active RF cavity amplifier is completed at one time, so there is no cumulative loss and phase difference of the traditional multi-stage series method combined with a large number of devices. In addition, the inherent loss of each cavity is much lower than the stripline structure used in traditional methods, so the efficiency and gain of the active RF cavity amplifier can reach the efficiency and gain of each transistor used. According to the other end of the present invention, the active RF cavity amplifier does not need a vacuum and has no complicated electrodes, circuits or windows, so each structural part can be mass-produced by a standard computer numerical control machine. And because the cavity is used to achieve merging and impedance matching, the active RF cavity amplifier does not need other discrete passive electronic components, thereby improving its reliability. Brief description of the drawings From the following detailed description in conjunction with the drawings, the above and other objects, features and advantages of the present invention will be apparent at a glance. The drawings are: Figure 1 is a perspective view of a prior art radio frequency cavity; Figure 2 is A perspective view of a part of the active RF cavity amplifier of the present invention; FIG. 3 is a top view of a general transistor package used in the active RF cavity amplifier of FIG. 2; The paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm (Centimeter)

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Fig. 4A is the active line branching line seen along line 4A-4A in Fig. 2; cavity amplifier of the frequency cavity amplifier Fig. 4B is an enlarged part of Fig. 4A, showing the active cheek cavity input / output cavity The guide rod is coupled to a transistor: and FIG. 4C is a side view of the coupling device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. All the well-known functions or structures in the following description are omitted to avoid blurring the focus. Please refer to FIG. 2, and the reference number (10) is the active RF cavity amplifier of the present invention. This amplifier contains two independently tuned resonant cavities (12, 14). The two cavities are joined together by a central plate (16) containing a plurality of transistors (18). The cavity (12) is coupled to the input line of the transistor (18), so it is called the input cavity. At the same time, the cavity (14) is coupled to the output line of the transistor (18) and is called the output cavity. As shown in Figure 2, the two cavities (12, 14) are roughly the same in terms of maintaining the resonant RF field, but different matching is required because of the impedance matching required for the input and output of the transistor. For the sake of simplicity, only the structure of the input cavity (丨 2) is described in detail later. The structure of the cover cavity (丨 4) is similar to the structure of the cavity (丨 2). The first cavity (12) is defined by a substantially cylindrical shell (20), and includes an open end (2 2), a closed end (2 4), and a center plate (16). The cavity (1 2) is defined by a first cylindrical wall (2 6) inside the cylindrical casing (20). The second cylindrical wall (2 8) formed by the annular cavity (30) defined by the casing (20) surrounds the cylindrical wall (2 6) as a radio frequency choke to prevent the transistor (丨 8) from operating during operation. The RF input is shorted. ______- 8- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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▲ 515225 A7 B7 V. Description of the invention (6 The second cylindrical wall (2 8) can also be used as another type of RF choke, such as the second cylindrical wall (28) extending outward from the cylindrical wall (26) without Those that are bent vertically are: The cylinder wall (28) contains a rounded edge (32) to connect the open end (22) of the casing (20) with the center plate (16). The cylindrical casing (20) is made of a conductive material such as Made of copper, metal or other conductive or superconducting material.

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The closed end (2 4) of the housing (20) defines an eyelet (3 4) to accommodate the plunger assembly (36). The plunger combination (36) includes a conductor disc (38), a dielectric disc (40), and a conductor plunger (42), which together constitute a coupling capacitor. Please refer to FIG. 4A, which shows a block circuit diagram of the plunger assembly (36). The plunger combination (36) additionally includes a coaxial portion (41) composed of a channel (44) and a central conductor (46) with a matching portion (48) for inputting and / or outputting RF power, such as an active RF amplifier (1 0) low input power and amplified power output from the amplifier. That is, the structure of the first or input cavity (12) (3 8, 40, 42, 46) couples low RF power from an external source into the first cavity (丨 2), and the second or output 2 cavity (1 4) The same structure combines the amplified RF power to a load outside the cavity. The tomb assembly (3 6) can be moved to the desired resonance frequency position manually or by screwing in the eyelet (3 4). As far as the desired operating frequency is concerned, the amount of movement of the plunger assembly (36) in the eyelet (34) can be approximately predicted. The central plate (16) is substantially circular, and includes an upper annular plate (50) defining the boundary of the first cavity (12), and a lower annular plate (52) defining the boundary of the second cavity (14). The upper and lower annular plates (50, 5 2) are combined by a circular structure (54), and a plurality of transistors (1 in a row) are arranged thereon. Figure 3 shows the transistors (1 8). Top view of the selected general transistor package. Bottom -9-This paper size applies to China National Standard (CNS) A4 (210X 297 mm) 515225 A7 B7 V. Description of the invention (7) The watch is identified by the special transistor type Its leads (18 X, 18y) and mounting flanges (18F) are used for both input and output, and conduct heat generated inside the transistor (18) to the cavity (12, 14) serving as a radiator. 〇BJT common base BJT common emitter field effect transistor 18x collector collector drain 18y emitter base gate 18F base emitter source In operation, DC power is passed through the guide rod (62a) and the wire (60a) is applied to the transistor leads (1 8 X, 1 8 y) (Figures 1 and 4 C). Since direct current must be applied to each transistor (1 8), it can be drawn in each transistor (1 8) Components such as ferrite washers are used in the pole or collector power supply circuit to ensure stable operation. The bias voltage applied to each input line (1 8 X) can be adjusted independently In order to overcome the inconsistency between the transistors used. The casing (20) and the central plate (16) are connected to the ground potential of the DC to ensure the safe operation of the active RF cavity amplifier (10). As shown in Figure 4C It is shown that between the guide rod (62 &) and each transistor input line (18 \), a ballast-containing device (55a) containing screws (64a) 'elastic yellow (66a) and an insulating portion (68a) is applied to the guide The pressure on the rod (62a) keeps it in contact. Please note that 'the upper engaging device (55a) is arranged on each transistor (18). If necessary, the guide rods (62a, b) can also be welded To the transistor leads (18x, y) to maintain contact. At the same time, the lower coupling device (55b) with the same structure as the upper coupling device (5 5b) is pressurized to the guide rod (62b). That is, the lower coupling device ( 55b) Coaxial coupling capacitors with guide rods (62b) are connected to the output lines of each transistor-10- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 515225

(18y) contact; the capacitor is formed by the guide rod (62b), the dielectric sleeve (70b) and the outer guide (7 2b) through the gap at the base of the output cavity (丨 4). The output RF power of (1 8) is coupled to the output core (1 4) through the guide rod (6 2 b). The output RF power combined from each crystal is greater than the input RF power from the source. The crystal (丨 8) is enlarged. Please / Wang Si, the lower coupling device (5 5 b) is equipped on each transistor (1 8). In other words, at each transistor (18), the structure (62a, 70a, 72a) or the coaxial coupling capacitor of the input 2 cavity (12) couples the RF field in the input cavity (12) to the transistor input line (丨 8 χ), and the coaxial coupling capacitor of the structure (6 2 b, 7 〇b, 7 2 b) or the output cavity (14) couples the RF field in the output cavity (14) to the transistor output line (18y). In low frequency applications, a chip capacitor can be used instead of a coaxial coupling capacitor. The RF field in the desired cavity mode, such as "TM01〇" mode, is coupled from the cavity (丨 4) to the load through the coupling capacitor component of the cavity (丨 4) plunger combination (36). These components include The conductive disc (38) 'the bottom surface of the dielectric disc (40) and the conductive cylinder plunger (42). As mentioned above, the function of the plunger assembly (36) is to extend the plunger (42). Enter the different ice degrees of each cavity to adjust the resonant frequency of each cavity. The depth can be changed manually or by an automatic control device. The coaxial portion (4) formed by the channel (4 4) of the plunger assembly (3 6) 1) and the center conductor (46) with the matching part (48), the amplified RF power is coupled out of the cavity through a standard coaxial connector. On the input side, the flow of RF power is opposite to that on the output side. That is, the input connector installed on the RF power from the plunger assembly (3 6) passes through the coaxial channel and the coupling capacitor and passes through the gap at the base of the input cavity (12) ", § -11-This paper Standards apply to China National Standard (CNS) A4 specifications (210X297 mm)

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k 515225 A7 B7 V. Description of the invention (: The components (62a, 70a, 72a) of the coaxial coupling electric appliance, and the input lead (18x) of the electric crystal moon (18). The components in the output cavity (14) And the corresponding components in the input 2 cavity (12), their structures and uses are similar. N Most of the conductive components in the active radio frequency cavity amplifier are good thermal contacts, so they become thermal unit bodies. Can be installed It is provided with an effective dust-cooled heat sink. It is also possible to easily complete liquid cooling by establishing a refrigerant channel in the center plate or in the conductive shell. The present invention has been shown and described with reference to certain specific examples. Those skilled in the arts will make various changes in form and details without departing from the principles of the invention of the attached patent. 1-12-This paper size applies to China National Standard (CNS) A4 (210X 297) %)

Claims (1)

515225 8 8 8 8 AB c D 6. Scope of patent application 1. An active RF cavity amplifier, comprising: a housing defining input and output cavities; a plurality of transistors mounted on the housing, each of which contains An input lead and an output lead; a first radio frequency power coupling device disposed in the housing adjacent to the input cavity to couple radio frequency power from its source into the input cavity to generate a radio frequency field; a first conductive combination having a plurality of conductors , Each arranged to contact each input lead of the transistor to couple the RF field in the input cavity to the input lead of the transistor; a second conductive combination having a plurality of conductors, each arranged to contact each output lead of the transistor , Coupling the RF field in the output cavity to the output lead of the transistor to amplify the RF power from the source; and a second RF power coupling device, which is arranged near the output cavity in the housing and outputs the amplified RF power from the output The cavity is coupled to a load. 2. For example, the active RF cavity amplifier of the scope of patent application, wherein the outer shell is cylindrical and defines a circular cavity surrounding the input cavity and a circular cavity surrounding the output cavity. 3. For example, the active RF cavity amplifier of the patent application No. 2 in which the annular cavity is configured as an RF choke coil to prevent short circuit of the amplified RF power. 4. For the active RF cavity amplifier of item 1 of the patent application, wherein the outer shell is made of a conductive material. 5. For example, the active RF cavity amplifier of the first patent application range, where the first and second rain RF power coupling devices each contain a plunger combination, the combination is -13- This paper size applies to China National Standard (CNS) A4 Specifications (210 X 297 mm) 515225 A8 B8 C8 D8 6. Scope of patent application. Equipped with a plunger to move inside the casing. 6. For the active RF cavity amplifier of item 5 of the patent application, wherein the plunger combination of the first RF power coupling device is configured to tune the resonant frequency of the input cavity, and the plunger of the second RF power coupling device is Resonant frequency for tuning output cavity. 7. The active RF cavity amplifier according to item 5 of the patent application, wherein the plunger combination includes: a coupling capacitor including a conductive cylinder plunger having first and second ends, at least one dielectric disc and the first The two ends are combined; and a coaxial portion containing a central conductor and a matching portion arranged in the cylindrical plunger channel. 8. A method of amplifying radio frequency power, comprising the steps of: coupling radio frequency power to an active radio frequency cavity amplifier including a housing defining an input cavity and an output cavity to generate a radio frequency field in the input cavity; and Multiple transistors are installed near the input and output cavity, each transistor has an input lead and an output lead; the resonant frequency of the input cavity and the resonant frequency of the output cavity are tuned; the radio frequency in the input cavity Field coupling to the input lead of the transistor; coupling the RF field in the output cavity to the output lead of the transistor to amplify the RF power from the source; and coupling the amplified RF power from the output cavity. 9. A radio frequency power amplifier comprising: an appliance for coupling radio frequency power to an active radio frequency cavity amplifier including a housing defining an input cavity and an output cavity; the coupling device is in the input cavity-14- This paper is for China National Standard (CNS) A4 specification (210X297 mm) Binding 515225 A8 B8 C8 D8 VI. Patent application scope • Generate RF field, install multiple transistors near the input cavity and output cavity, each transistor has input leads and output leads; and put the input cavity into the input cavity A radio frequency field is coupled to the input lead of the transistor and a device for coupling the radio frequency field in the output cavity to the transistor output lead. 10. If the RF power amplifier of item 9 of the patent application scope includes: an apparatus for tuning the input cavity resonance frequency and an output cavity resonance frequency; and an apparatus for coupling the amplified RF power from the output cavity. 11. A radio frequency power amplifier, comprising: an active radio frequency cavity amplifier that couples radio frequency power to a housing that defines an input cavity and an output cavity; the coupling device generates a radio frequency field in the input cavity and an input cavity And a plurality of transistors are installed near the output cavity; each transistor includes an input lead and an output lead; and a device for tuning the input cavity resonant frequency and the output cavity resonant frequency. 12. For example, the RF power amplifier in the scope of patent application No. 11 further includes: coupling the RF field in the input cavity to the input lead of the transistor and coupling the RF field in the output cavity to the output lead of the transistor Appliances; and appliances that couple amplified RF power from the output cavity. -15- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)