A microwave physiotherapy radiator based on lumped element loading

Abstract

A microwave physiotherapy radiator based on lumped element loading, comprising a cylindrical metal cavity, one side end face of the cylindrical metal cavity being a radiation port face, the radiation port face being a circular radiation face, the other side end face of the cylindrical metal cavity being provided with a feeding port outside; two metal oscillators are symmetrically arranged inside the cylindrical metal cavity, and a lumped capacitor is arranged between the two metal oscillators; the feeding port is connected with the two metal oscillators through a coaxial feeding needle and a double-conductor transmission line, wherein one end of the coaxial feeding needle is connected with the feeding port, the other end of the coaxial feeding needle is connected with one side of the double-conductor transmission line, the other side of the double-conductor transmission line is connected with a folded metal sheet, and the two sides of the double-conductor transmission line are connected with end portions of the two metal oscillators; the folded metal sheet is placed vertically in parallel with the coaxial feeding needle. The present application reduces the resonant frequency of the radiator, reduces the size of the radiator, the whole microwave thermal field of the radiator is uniformly distributed, the microwave leakage is prevented, the lumped capacitor is easy to replace, and the inductance of the whole radiator is reduced.

Description

Technical Field

[0001] This invention relates to the field of microwave physiotherapy equipment technology, and specifically to a microwave physiotherapy radiator based on lumped element loading. Background Technology

[0002] In recent years, microwave therapy devices have been widely used in clinical treatment and have great application prospects. Currently, the microwave physiotherapy methods used in China are all internal radiation devices. Compared with external radiation devices, it is difficult to achieve painless and non-invasive treatment effects, and they are more likely to cause some damage to healthy tissues. External radiation devices irradiate injured tissues, utilizing the unique physical properties of microwaves—namely, biothermal and non-thermal effects—to promote the absorption of nutrients in diseased tissues, repair blood and fluid circulation, enhance local tissue immunity, and restore the normal function of diseased tissues and organs.

[0003] Among them, the microwave radiator is a key component of the microwave physiotherapy device. Its function is to radiate microwave energy through the radiator and directly act on the diseased area of ​​human tissue, heating the diseased tissue to above 42°C and controlling the temperature of the surrounding healthy tissue below 44°C, thereby achieving the effect of microwave physiotherapy.

[0004] Currently, the commonly used microwave frequencies for microwave therapy radiators on the market are 433MHz, 915MHz, and 2450MHz. Different frequencies correspond to different depths of penetration into human tissue. The penetration depth of 433MHz is approximately 7cm-15cm, that of 915MHz is approximately 4cm-7cm, and that of 2450MHz is approximately 1cm-3cm. Clearly, microwave therapy radiators with better penetration are more effective in treating human tissue; therefore, 433MHz microwave therapy radiators are widely used in clinical medicine.

[0005] Currently, in the field of microwave therapy technology, the standard size of a hollow rectangular waveguide for a 433MHz microwave therapy radiator is 457mm × 272mm, while the standard size of a hollow circular waveguide is approximately 460mm. In clinical medical applications, excessively large aperture sizes are inconvenient for treatment, thus requiring a reduction in the aperture size of the microwave therapy radiator. Current microwave therapy radiators on the market utilize various methods, such as adding loading dielectric materials or increasing the loading quadrant. While these methods reduce the aperture size, they also increase weight or complexity, making manufacturing more difficult and costly.

[0006] In current clinical medicine, microwave therapy radiators suffer from severe microwave leakage and uneven heat field distribution, which can cause overheating of fat areas in the body during treatment. Furthermore, current microwave therapy radiators are highly sensitive and easily affected by the environment. When changes occur in the body's diseased tissue or the distance between the radiator and the tissue changes, the radiator's resonant frequency and standing wave ratio will change, causing mismatch and malfunction, severely limiting its clinical application. Summary of the Invention

[0007] The purpose of this invention is to address the problems in the prior art by providing a microwave therapy radiator based on lumped element loading. This not only solves the problems of large overall structural size, severe microwave leakage, and uneven distribution of radiated heat field in current microwave radiators, but also introduces a dual-conductor transmission line, enabling wide-band, low-loss transmission of microwave signals. Most importantly, the lumped capacitor is introduced, increasing the overall system's capacitance and significantly reducing the impact of the environment on the radiator, including changes in human diseased tissue and changes in the distance between the circular radiating surface and human tissue. Furthermore, the lumped capacitor is easy to replace, and the microwave therapy radiator is easy to debug and assemble, facilitating clinical application.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A microwave physiotherapy radiator based on lumped element loading includes a cylindrical metal cavity. One end face of the cylindrical metal cavity is a radiation port, which is a circular radiation surface. A feed port is provided on the outer side of the other end face of the cylindrical metal cavity. Two metal oscillators are symmetrically arranged inside the cylindrical metal cavity about the center of the cavity, and a lumped capacitor is provided between the two metal oscillators. The feed port is connected to the two metal oscillators through a coaxial feed needle and a dual-conductor transmission line. One end of the coaxial feed needle is connected to the feed port, and the other end of the coaxial feed needle is connected to one side of the dual-conductor transmission line. The other side of the dual-conductor transmission line is connected to a folded metal sheet, and both sides of the dual-conductor transmission line are connected to the ends of the two metal oscillators. The folded metal sheet is placed vertically parallel to the coaxial feed needle.

[0010] As a preferred embodiment, the diameter L of the cylindrical metal cavity ranges from 140mm to 170mm, and the height H ranges from 45mm to 110mm.

[0011] As a preferred embodiment, the width G1 of the gap between the two sides of the dual conductor transmission line is in the range of 1mm-2mm, and the length H1 is in the range of 30mm-85mm.

[0012] As a preferred embodiment, the metal oscillator has a T-shaped arc structure, and the two metal oscillators are centrally symmetrical about the center of the cylindrical metal cavity.

[0013] As a preferred embodiment, the radius L1 of the T-shaped arc structure ranges from 50mm to 80mm, and the half-angle θ of the quarter arc ranges from 45° to 70°.

[0014] As a preferred embodiment, the folded metal sheet has an inverted L-shaped structure, with its horizontal portion connected to the dual-conductor transmission line and its vertical portion connected to the inner side of the end face of the cylindrical metal cavity; the height H2 of the folded metal sheet ranges from 11mm to 14mm.

[0015] As a preferred embodiment, the capacitance value C of the lumped capacitor is in the range of 0pF-20pF, and the lumped capacitor is replaceable.

[0016] As a preferred embodiment, the cylindrical metal cavity, coaxial feed needle, folded metal sheet, dual conductor transmission line, and metal oscillator are made of any one of gold, silver, copper, and aluminum.

[0017] As a preferred embodiment, the gap between the two sides of the dual-conductor transmission line is filled with a dielectric material, which is air or Teflon.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] This invention's microwave therapy radiator uses a cylindrical metal cavity, coaxial feed pin, dual-conductor transmission line, and metal vibrators as an integrated structure for excitation antennas. This reduces the resonant frequency of the overall antenna structure, allowing for a smaller aperture of the circular radiating surface at the same microwave frequency, thus achieving miniaturization and facilitating clinical applications. The invention incorporates a folded metal sheet, placed vertically parallel to the coaxial feed pin, to achieve impedance matching and effectively reduce the radiator's standing wave ratio (VSWR). The feed port of the microwave therapy radiator is connected to two metal vibrators via the coaxial feed pin and dual-conductor transmission line. By introducing the dual-conductor transmission line, electrolyte material can be added between the two conductors, enabling the radiator to transmit microwave signals with wide bandwidth and low loss, thereby improving its radiation efficiency. The microwave physiotherapy radiator of this invention incorporates a lumped capacitor. Because the internal antenna structure is a metal sheet, the antenna is highly inductive, and its resonant frequency is easily affected by the environment. Factors such as the distance between the human body tissue and the physiotherapy device, the size of the metal sheet, and changes in the diseased tissue of the human body can all affect the resonant frequency and standing wave ratio. This invention adds a lumped capacitor, which increases the capacitance of the entire system. At the same time, the lumped capacitor is easy to replace, the machine is easy to assemble and debug, easy to match, and is not easily affected by the environment.

[0020] Furthermore, the metal oscillator of the microwave physiotherapy radiator of the present invention has a T-shaped arc structure, which is a semi-enclosed structure, allowing the thermal field and microwave energy to be radiated outward more evenly. At the same time, the semi-enclosed structure effectively reduces microwave leakage, so as to meet the national standard requirements for the safety performance of radiators in medical electrical equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall three-dimensional structure of a microwave physiotherapy radiator based on lumped element loading according to an embodiment of the present invention;

[0022] Figure 2 This is a top view schematic diagram of a microwave physiotherapy radiator based on lumped element loading according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the main structure of a microwave physiotherapy radiator based on lumped element loading according to an embodiment of the present invention;

[0024] Figure 4 The figure shows the S-parameter simulation results of the excitation antenna of the microwave physiotherapy radiator in this embodiment of the invention under the optimal size structure and lumped capacitance.

[0025] Figure 5 The figure shows the S-parameter simulation results of the excitation antenna of the microwave physiotherapy radiator in this embodiment of the invention without loading lumped capacitance;

[0026] Figure 6 This is a simulation result of the standing wave ratio parameter when the distance d1 between the circular radiating surface of the microwave physiotherapy radiator and the human tissue model changes according to an embodiment of the present invention.

[0027] Figure 7 This is a simulation result of the standing wave ratio parameter of the microwave physiotherapy radiator according to an embodiment of the present invention when the distance d1 between the circular radiating surface and the human tissue model changes without loading the lumped capacitance.

[0028] Figure 8 This is a volume loss density diagram of a human lesion tissue under optimal size, structure, and lumped capacitance for a microwave therapy radiator according to an embodiment of the present invention.

[0029] In the attached diagram: 1-cylindrical metal cavity; 2-circular radiating surface; 3-feed port; 4-coaxial feed pin; 5-folded metal sheet; 6-double conductor transmission line; 7-metal oscillator; 8-lumped capacitor. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Example 1

[0035] See Figures 1 to 3 This invention proposes a microwave radiator based on lumped element loading, whose main structure includes a cylindrical metal cavity 1, a circular radiating surface 2, a feed port 3, a coaxial feed pin 4, a folded metal sheet 5, a dual-conductor transmission line 6, a metal vibrator 7, and a lumped capacitor 8. The circular radiating surface 2 is the radiating port of the cylindrical metal cavity 1. The feed port 3 is connected to the dual-conductor transmission line 6 and the metal vibrator 7 via the coaxial feed pin 4. These three integral structures—the cylindrical metal cavity 1, the dual-conductor transmission line 6, and the metal vibrator 7—constitute the excitation antenna of the radiator.

[0036] In one embodiment of the present invention, the circular radiating surface 2 is the top surface of the cylindrical metal cavity 1, and the feed port 3 is on the bottom surface of the cylindrical metal cavity 1. The feed port 3 is connected to the coaxial feed needle 4, and then connected to the metal vibrator 7 through the double conductor transmission line 6. Microwaves pass through the feed port 3, the coaxial feed needle 4, the double conductor transmission line 6, and the metal vibrator 7. Finally, the microwave energy is excited in the cylindrical metal cavity 1 and radiated out through the circular radiating surface 2, acting on the diseased tissue of the human body, thereby realizing microwave physiotherapy on the human body tissue. The present invention introduces a lumped capacitor 8, which reduces the inductance of the overall system and reduces the influence of the environment on the microwave physiotherapy radiator. At the same time, the lumped capacitor is easy to replace, the machine is easy to assemble and debug, and easy to match.

[0037] In one possible implementation, the diameter of the cylindrical metal cavity 1 is denoted as L, and the height is denoted as H, where L ranges from 140mm to 170mm, and H ranges from 45mm to 110mm. Furthermore, in this invention, the optimal value for the diameter L of the cylindrical metal cavity 1 is 150mm, and the optimal value for the height H is 50mm.

[0038] In one possible implementation, the gap width between the two conductor transmission lines 6 is denoted as G1, and the length of the two conductor transmission lines is denoted as H1, where G1 ranges from 1mm to 2mm, and H1 ranges from 30mm to 85mm. Furthermore, the optimal value for the gap width G1 between the two conductor transmission lines 6 is 2mm, and the optimal value for the length H1 is 40mm.

[0039] In one possible implementation, the metal oscillator 7 is a T-shaped arc structure, symmetrical about the center of the cylindrical metal cavity 1. Its arc radius is denoted as L1, and its quarter-arc half-angle is denoted as θ, where L1 ranges from 50mm to 80mm, and θ ranges from 45° to 70°. Furthermore, in this invention, the optimal value for the arc radius L1 of the symmetrical metal oscillator 7 is 70mm, and the optimal value for the quarter-arc half-angle θ is 63°.

[0040] In one possible implementation, the folded metal sheet 4 is placed vertically parallel to the coaxial feed needle 4, and its height is denoted as H2, where the value of H2 ranges from 11mm to 14mm. Furthermore, the optimal value of the height H2 of the folded metal sheet 4 is 13mm.

[0041] In one possible implementation, the lumped capacitor 8 is located in the middle of the symmetrical metal oscillator 7, and its capacitance value is denoted as C, with a range of 0pF-20pF. Furthermore, in this invention, the optimal value of the capacitance C of the lumped capacitor 8 is 10pF.

[0042] In one possible implementation, the cylindrical metal cavity 1, the coaxial feed needle 4, the folded metal sheet 5, the dual-conductor transmission line 6, and the metal oscillator 7 can be made of any of the following metal materials: gold, silver, copper, aluminum, etc. Furthermore, in this invention, the cylindrical metal cavity 1 is made of aluminum, and all other metal materials are made of copper.

[0043] In one possible implementation, the gap between the two conductor transmission lines 6 can be filled with a dielectric material, which can be air, Teflon, or other dielectric materials. Furthermore, in this invention, the dielectric material used is Teflon.

[0044] Example 2

[0045] Example 2 has the same overall structure as Example 1, with only minor adjustments to the following parameters.

[0046] In this embodiment, the diameter L of the cylindrical metal cavity 1 is 150 mm, and the height H is 100 mm.

[0047] In this embodiment, the gap width G1 between the two conductor transmission lines 6 is 1.5 mm, and the length H1 of the two conductor transmission lines 6 is 90 mm.

[0048] In this embodiment, the radius L1 of the metal oscillator 7 is 68mm, and the quarter-arc half-angle θ is 60°.

[0049] In this embodiment, the height H2 of the folded metal sheet 4 is 12mm.

[0050] In this embodiment, the capacitance C of the lumped capacitor 8 is 1pF.

[0051] In this embodiment, the cylindrical metal cavity 1 is made of aluminum, and the other metal materials are all copper.

[0052] In this embodiment, the dielectric material filling the gap between the two conductor transmission lines 6 is air.

[0053] The following simulation verifies the effect of the microwave therapy radiator based on lumped element loading of the present invention.

[0054] 1. Simulation conditions

[0055] A human tissue model is placed above the circular radiating surface of the microwave physiotherapy radiator. It is assumed that the dielectric constant of the human tissue model is 55 and the conductivity is 0.92 S / m. The distance between the human tissue model and the circular radiating surface is denoted as d1, where d1 takes three values: 10 mm, 20 mm, and 30 mm.

[0056] 2. Simulation Content

[0057] Electromagnetic simulations were performed on the above simulation model using the commercial simulation software HFSS_19.0. The results obtained, including S-parameters, standing wave ratio, and human tissue loss density, are as follows: Figures 5 to 8 As shown. 3. Simulation Results

[0058] Figure 4 The image shows the simulation curve of the reflection coefficient of the excitation antenna of this invention under optimal size structure and optimal lumped capacitance. Figure 4 The horizontal axis represents the frequency set during the simulation, in MHz, ranging from 300MHz to 600MHz. Figure 4 The vertical axis represents the return loss set during the simulation, i.e., the magnitude of the reflection coefficient (S11) in decibels, in dB, ranging from 0dB to -22.5dB.

[0059] from Figure 4 It can be clearly seen that the resonant point of the reflection coefficient curve of the excitation antenna in this invention is around 433MHz. At a frequency of 433MHz, the corresponding return loss is -20.30dB. The results indicate that the return loss (S11) of the microwave therapy radiator under this size structure and lumped capacitance can achieve the optimal value, and the impedance bandwidth is the largest at this time. The standing wave ratio of the microwave therapy radiator is small and the radiation efficiency is high.

[0060] Figure 5 The simulation curve of the reflection coefficient of the excitation antenna of this invention without loading lumped capacitance (under optimal size structure) is shown. Figure 5 The horizontal axis represents the frequency set during the simulation, in MHz, ranging from 300MHz to 600MHz. Figure 5 The vertical axis represents the return loss set during the simulation, i.e., the magnitude of the reflection coefficient (S11) in decibels, in dB, ranging from 0dB to -12dB.

[0061] from Figure 5 It can be clearly seen that the resonant point of the reflection coefficient curve of the excitation antenna in this invention is around 433MHz. At a frequency of 433MHz, the corresponding return loss is -11.42dB. Figure 4 Compared with the results, it can be seen that without loading the lumped capacitance, the microwave physiotherapy radiator has a large standing wave ratio, narrow impedance bandwidth, high microwave transmission loss, and low radiation efficiency.

[0062] Figure 6 The image shows the simulation curves of the standing wave ratio (SWR) of the excitation antenna of this invention under optimal size and structure and optimal lumped capacitance, with distances d1 between the circular radiating surface and the human tissue model being 10mm, 20mm, and 30mm. Figure 5 The horizontal axis represents the frequency set during the simulation, in MHz, ranging from 300MHz to 600MHz. Figure 5 The vertical axis represents the standing wave ratio set during the simulation, ranging from 0 to 30. The variable is the distance d1 between the circular radiation surface and the human tissue model, which is 10 mm, 20 mm, and 30 mm respectively. The three standing wave ratio variations are represented by different curves.

[0063] from Figure 6 The graph clearly shows the standing wave ratio (SWR) as the distance between the radiator and the human body changes. It indicates that when the distance varies from 10mm to 30mm, the SWR is around 2. This demonstrates that, given this size, structure, and lumped capacitance, the SWR of the microwave therapy radiator is less than 3 near 433MHz, and the radiator is not easily affected by environmental factors.

[0064] Figure 7 The above are simulation curves of the standing wave ratio (SWR) of the excitation antenna of this invention under optimal structural dimensions (without lumped capacitance) and with distances d1 between the circular radiating surface and the human tissue model being 10mm, 20mm, and 30mm. Figure 5 The horizontal axis represents the frequency set during the simulation, in MHz, ranging from 300MHz to 600MHz. Figure 5 The vertical axis represents the standing wave ratio set during the simulation, ranging from 0 to 60. The variable is the distance d1 between the circular radiation surface and the human tissue model, which is 10mm, 20mm, and 30mm respectively. The three standing wave ratio variations are represented by different curves.

[0065] from Figure 7 The graph clearly shows the standing wave ratio (SWR) as the distance between the radiator and the human body changes. It indicates that when the distance varies from 10mm to 30mm, the SWR is approximately 5-10. Figure 6 Compared to the results, this microwave therapy radiator is more susceptible to environmental influences. When the distance d1 changes or when the diseased tissue in the human body changes, the microwave therapy radiator cannot function properly.

[0066] Figure 8 The simulation results of the loss density of human tissue under the optimal size structure and optimal lumped capacitance of the excitation antenna of this invention are presented below. Figure 6 It can be clearly seen that microwave energy is evenly distributed on the surface of the human body and penetrates deep into the body, which can achieve good therapeutic effects. In addition, the microwave therapy radiator has a uniform heat field distribution, good penetration and little microwave leakage.

[0067] In summary, this invention, based on a lumped-element loaded microwave therapy radiator, achieves a lower resonant frequency compared to currently available microwave therapy radiators with optimal size, structure, and lumped capacitance. The excitation antenna, composed of a cylindrical metal cavity, a dual-conductor transmission line, and a metal vibrator, reduces the radiator's aperture size and microwave leakage, meeting the national standards for medical electrical equipment safety performance requirements. Furthermore, this radiator transmits wideband, low-loss microwave signals, improving microwave radiation efficiency and impedance bandwidth. Finally, the introduction of lumped capacitance increases the radiator's capacitive properties, resulting in a uniform microwave radiation heat field distribution that is less susceptible to environmental influences, including changes in diseased tissue and the distance between the tissue and the circular radiating surface. Moreover, the lumped capacitor in this invention is easily replaceable, facilitating radiator debugging and clinical application.

[0068] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A microwave diathermy applicator based on lumped element loading, characterized in that, The application relates to a cylindrical metal cavity (1), one side end face of which is a radiation port face, the radiation port face is a circular radiation face (2), and the other side end face of the cylindrical metal cavity (1) is provided with a feeding port (3) outside; the inside of the cylindrical metal cavity (1) is provided with two metal oscillators (7) in symmetry about the center of the cylindrical metal cavity (1), and a lumped capacitor (8) is arranged between the two metal oscillators (7); the feeding port (3) is connected with the two metal oscillators (7) through a coaxial feeding needle (4) and a double-conductor transmission line (6), wherein one end of the coaxial feeding needle (4) is connected with the feeding port (3), the other end of the coaxial feeding needle (4) is connected with one side of the double-conductor transmission line (6), the other side of the double-conductor transmission line (6) is connected with a folded metal sheet (5), and the two sides of the double-conductor transmission line (6) are connected with the end portions of the two metal oscillators (7); the folded metal sheet (5) is vertically placed in parallel with the coaxial feeding needle (4). The metal oscillator (7) is a T-shaped arc structure, and the two metal oscillators (7) are centrally symmetrical about the center of the cylindrical metal cavity (1). The folded metal sheet (5) is a reverse L-shaped structure, the horizontal part of which is connected with the double-conductor transmission line (6), and the vertical part is connected to the inside of the end face of the cylindrical metal cavity (1).

2. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The diameter L of the cylindrical metal cavity (1) ranges from 140 mm to 170 mm, and the height H ranges from 45 mm to 110 mm.

3. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The gap width G1 of the two sides of the double-conductor transmission line (6) ranges from 1 mm to 2 mm, and the length H1 ranges from 30 mm to 85 mm.

4. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The arc radius L1 of the T-shaped arc structure ranges from 50 mm to 80 mm, and the quarter-arc half-angle theta ranges from 45 DEG to 70 DEG.

5. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The height H2 of the folded metal sheet (5) ranges from 11 mm to 14 mm.

6. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The capacitance C of the lumped capacitor (8) ranges from 0 pF to 20 pF, and the lumped capacitor (8) can be replaced.

7. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The manufacturing materials of the cylindrical metal cavity (1), the coaxial feeding needle (4), the folded metal sheet (5), the double-conductor transmission line (6) and the metal oscillator (7) are any one of gold, silver, copper and aluminum.

8. The lumped element loaded microwave diathermy applicator of claim 1, wherein, The gap between the two sides of the double-conductor transmission line (6) is filled with a dielectric, and the dielectric material is air or Teflon.

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