102 results about "Circular waveguide" patented technology

The invention belongs to the field of particle accelerator microwaves, and particularly relates to a C-band compact spherical microwave pulse compression device which comprises a shell, a dual-polarization mode coupler and a circular waveguide, a spherical energy storage cavity is formed in the shell, and the circular waveguide and the spherical energy storage cavity are communicated through a coupling hole; the dual-polarization mode coupler comprises a rectangular waveguide, a butterfly-shaped matching section and a cylindrical matching section. According to the klystron radio frequency pulse compression circuit, the radio frequency pulse with the pulse width of 2.5 microseconds of the klystron can be compressed to 300ns, the average power gain in a single pulse is more than 4 times, the peak power gain is 6.3 times, and the compression efficiency is about 54%. According to the dual-polarization mode coupler, the functions of power distribution, mode conversion and polarization mode generation are synchronously realized, a TE10 mode in a rectangular waveguide is converted into two polarization TE11 modes which are equal in amplitude and orthogonal in phase, and then the two orthogonal TE114 modes are excited in a spherical energy storage cavity.

According to one embodiment, an introduction-side rectangular waveguide tube and a lead-out-side rectangular waveguide tube are each connected to a circular connection plate connected to an end surface of the circular waveguide tube, and at least one connection plate includes, in an outer circumference thereof, the other welding collar welded to the one welding collar, and both the one welding collar and the other welding collar include grooves or holes for a rotation regulation jig to regulate rotation in a circumferential direction, and an entire portion along the circumferential direction including the grooves or holes is welded and fixed thereto.

The application discloses a ternary computing method and system based on a double-chain difference coupling principle. A difference value (XnYn) is directly generated by a forward component Xn and a reverse component Yn in a difference coupling area, forming a three-value logic {‑1, 0, +1}, and a threshold comparison circuit is omitted, and operation follows BH=Σ(XnYn)×3^n. A hierarchical logic system composed of basic operators, minimum complete operators and global operators is constructed, and arbitrary three-value logic operation is realized; a circular waveguide structure is adopted to configure an optical path difference, so that coherent light directly forms three interference states at an output end, and optical three-value logic gates and optical full adders are realized; a double-chain six-bit structure is adopted for symbol coding, a two-dimensional geometric framework is driven to generate a symbol form, and logical and geometric expression unification is realized.

The present invention discloses a broadband, high-efficiency circular waveguide TE31 mode exciter, belonging to the field of microwave and millimeter wave technology. The exciter comprises a standard TE10 mode rectangular waveguide section, a TE10 mode-TE30 mode conversion section, a standard TE30 mode rectangular waveguide section, a TE30 mode-TE31 mode conversion section, and a TE31 mode circular waveguide section, all connected in sequence. The excitation process of the TE31 mode exciter is divided into two steps: first, converting the TE10 mode to the TE30 mode, and then converting it to the TE31 mode. With the cooperation of a power divider, a torsion waveguide, and a gradient waveguide, the conversion from the rectangular waveguide TE10 mode to the circular waveguide TE31 mode is achieved, reducing losses during the conversion process and ensuring conversion efficiency.

The invention discloses a millimeter wave communication antenna broadband feed source network four-port device and an application method thereof, and relates to the technical field of microwave communication, the millimeter wave communication antenna broadband feed source network four-port device comprises a circular rectangular transition structure, a circular polarizer and an orthogonal mode coupling duplexer assembly which are integrated in sequence; the circular rectangular transition structure is used for corresponding conversion transition between the standard rectangular waveguide and the circular waveguide; the circular polarizer is provided with an orthogonal stepped ridge, so as to convert the circularly polarized wave into an orthogonal linearly polarized wave or convert the orthogonal linearly polarized wave into the circularly polarized wave corresponding to the signal receiving and transmitting direction; the orthogonal mode coupling diplexer assembly is used for separating the two paths of orthogonal linear polarized waves in the synthetic state or synthesizing the two paths of orthogonal linear polarized waves in the separated state corresponding to the signal receiving and transmitting direction, and can screen signals passing through a specific receiving and transmitting frequency band. The technical problems that in the prior art, a dual-polarized antenna technology for dual-channel communication is large in size, complex in structure and high in cost, and the overall performance is difficult to meet expected requirements are solved.

The invention discloses a spiral structure waveguide for vortex light topological charge conversion and an implementation method thereof, and belongs to the field of optical waveguides. The circular waveguide and the spiral structure are combined, the spiral structure is used for regulating and controlling the vortex light mode according to the mode conversion matching condition, and vortex light conversion between any topological charge orders is achieved; according to the invention, complete conversion between different vortex lights is realized, two vortex light mixed beams with different proportions can be generated, and the requirements of generation and utilization of vortex lights with different orders in an integrated photonics on-chip structure are met. According to the method, the problem that topological charges cannot be freely converted among different vortex light modes in a waveguide structure is solved, the application value of the waveguide structure in the aspect of vortex light regulation and control is expanded, and the possibility is provided for an integrated photon platform to utilize vortex light topological charge degree-of-freedom coding information and process calculation tasks. According to the invention, information coding, optical communication, calculation and other applications are carried out by changing the topological charge of the vortex light.

The invention discloses a quasi-single-mode circular waveguide conical horn antenna, a radar and a communication device. The quasi-single-mode circular waveguide conical horn antenna comprises a circular waveguide section and a conical horn section. Conductor loss is reduced by remarkably increasing the diameter of the circular waveguide, and axial periodic annular grooves are formed in the inner wall of the circular waveguide to form a spatial mode filter and a selective attenuation high-order mode, so that high radiation efficiency and high mode purity are realized at the same time in a millimeter wave frequency band. And the conical horn section adopts an index profile to realize high-directionality radiation. The antenna structure effectively solves the technical problems of large loss and impure mode in a millimeter wave high-frequency band in the traditional design.

In one embodiment, the present disclosure is directed to a system for providing improved electric field uniformity to a plasma chamber receiving multiple signal inputs. The system includes one or more dielectrics distributing received energy to one or more antennas. The one or more dielectrics have N receiving areas. N circular waveguides are positioned over the N receiving areas. Each of waveguides has a mode converter converting a received first transverse mode signal to a second transverse mode signal to be output by the circular waveguide to the corresponding receiving area. At least one phase adjuster circuit adjusts the phase of at least one of the first transverse mode signals such that adjacent circular waveguides have their received first transverse mode signals differ in phase by approximately 360 / N.

The application discloses a gynecological millimeter wave therapeutic instrument, which comprises a host computer, an antenna mechanism connected with the host computer, the antenna mechanism comprising sequentially connected circular waveguide, millimeter wave antenna and antenna protective cover, the host computer and the antenna mechanism being connected along the same axial direction. The host computer comprises a millimeter wave source and a wave form conversion and attenuation device, the wave form conversion and attenuation device comprising an attenuation unit and a wave form conversion unit integrated into one mechanism, the attenuation unit being connected with the millimeter wave source through a flange, the wave form conversion unit being connected with the circular waveguide, the attenuation unit being adapted to attenuate the millimeter wave power emitted by the millimeter wave source to a target value, and the wave form conversion unit being adapted to convert the field type of the millimeter wave after power attenuation from TE10 wave in the rectangular waveguide into circular polarization wave in the circular waveguide, so as to provide the required millimeter wave output power for the millimeter wave antenna. The gynecological therapeutic instrument can perform accurate irradiation treatment in the gynecological cavity, and can ensure a larger millimeter wave adjustment range without changing the millimeter wave source.

The invention provides a shielding structure of a plasma source, a design method of the shielding structure and plasma processing equipment, and relates to the technical field of electromagnetic shielding, the plasma source comprises a solenoid, the shielding structure comprises a shielding body surrounding the solenoid, and the shielding body is provided with at least one shielding channel designed based on the cut-off waveguide theory. The method is used for suppressing electromagnetic leakage on the premise of ensuring physical communication. The shielding channel comprises a ventilating window which is arranged on the side surface of the shielding body and is used for radiating, a circular waveguide tube which is used for a pipeline to pass through and is connected with an external hose fixing piece and is provided with a thread, and a segmentable waveguide tube which is used for a growth sample cavity to pass through. By constructing a shielding body, a solenoid in a plasma source is shielded in all directions; by reasonably designing the size and layout of the waveguide structure, efficient suppression of radio frequency energy is realized, the failure of the sensor caused by electromagnetic interference is solved, and stable operation of plasma processing equipment is guaranteed.

The invention discloses an antenna optimization method, system and device based on a QVE frequency band feed source network, and a medium, and relates to the technical field of antennas. The method comprises the following steps: acquiring a QVE frequency band illumination angle parameter and an edge illumination level parameter; calculating the standard radius of the circular waveguide and establishing a longitudinal groove geometric parameter constraint relation to obtain longitudinal groove differential geometric parameters; determining a first orthogonal support arm length deviation value and a broadside structure parameter of the first-stage turnstile structure by taking a preset phase difference angle of orthogonal polarization radio frequency signals of the first-stage turnstile structure as a target; constructing a dual circular polarization network and a stepped transition structure; constructing a power combiner and a Chebyshev impedance matcher; and integrating the differential longitudinal slot feed source, the dual-circular polarization network and the orthogonal mode converter to obtain a QVE frequency band feed source network, and performing antenna feed through the QVE frequency band feed source network. By implementing the technical scheme provided by the invention, the feed efficiency of the antenna system can be improved, so that the performance of the antenna system is enhanced.

The invention discloses an input coupler of a convolution traveling wave amplifier, and belongs to the technical field of microwave devices. The coupler for converting the rectangular waveguide TE10 mode into the circular waveguide TE11 mode structurally and mainly comprises an input rectangular waveguide, an electron beam circulation end and an output circular waveguide, the rectangular waveguide is connected with the circular waveguide, and the electron beam circulation end is completely communicated with the output circular waveguide. The electron beam circulation end is composed of a plurality of cylindrical resonant cavities, and the number, the radius and the width of the cylindrical resonant cavities are matched with the working frequency of the device. Compared with a traditional input coupler, the input coupler disclosed by the invention ensures that a TE11 mode is output by the output circular waveguide in a single direction by utilizing a multi-diffraction principle of a plurality of cylindrical resonant cavities, and the transmission and purity of the output circular waveguide TE11 mode can be improved; meanwhile, the electron beam circulation end is an open end, and a large space can be provided for electron beam circulation.

The invention discloses a high-power-capacity power divider based on a mixed mode, and belongs to a power distribution / synthesis technology in the technical field of high-power microwaves. The objective of the invention is to solve the problems of insufficient power capacity and coaxial inner conductor end surface electric field concentration caused by small cross section size when an existing power divider is applied to high frequency. The power divider integrates circular waveguide TM0n mixed mode excitation, conversion from a mixed mode to a coaxial waveguide TEM mode and an inner conductor end face strong field control technology, and comprises an input circular waveguide, inclined plane transition, a large over-mode ratio circular waveguide, a coaxial waveguide, a radial line and a rectangular waveguide, and a groove is formed in the inner conductor end face of the coaxial waveguide. While the waveguide section is increased to improve the power capacity of the main body structure, the end surface electric field peak value is effectively inhibited, and the system power capacity is improved. The invention is mainly applied to a microwave system requiring high power distribution or synthesis, and has the advantages of high power capacity, low surface electric field, high conversion efficiency and wide working bandwidth.

The application discloses a kind of based on super surface rectangular waveguide mode conversion device and method, for realizing TE 10 -TE 20 -TE 01 Metal waveguide mode conversion, rectangular waveguide mode conversion device includes first to fifth section waveguide, and first to second super surface structure, wherein: first, third, fifth section waveguide is used to transmit rectangular waveguide TE 10 Mode, rectangular waveguide TE 20 Mode and circular waveguide TE 01 Mode, second, fourth section waveguide is used to generate multimode interference;First super surface structure is used to realize TE 10 Mode to TE 20 Mode conversion, second super surface structure is used to realize TE 20 Mode to TE 01 Mode conversion;Second section waveguide, first super surface structure and third section waveguide constitute TE 10 -TE 20 Mode converter;Fourth section waveguide and second super surface structure constitute TE 20 -TE 01 Mode converter.The application utilizes the regulation and control ability of super surface to electromagnetic field, and rectangular waveguide TE 10 Mode can be converted into circular waveguide TE 01 Mode in smaller space.

The present invention discloses a K / Ka band dual-frequency conical beam antenna, comprising a high-frequency filtering and feeding module, a low-frequency power splitting and feeding module, and a nested horn module; the nested horn module comprises a circular waveguide horn and a coaxial horn nested outside the circular waveguide horn; the high-frequency filtering and feeding module is used to filter and perform mode conversion on input high-frequency electromagnetic energy, and output electromagnetic waves in a coaxial TEM mode; the electromagnetic waves in the coaxial TEM mode are used to excite the circular waveguide horn; the low-frequency power splitting and feeding module is used to perform power distribution on the input low-frequency electromagnetic energy, and output a plurality of electromagnetic waves with equal amplitude and phase; the plurality of electromagnetic waves with equal amplitude and phase are used to symmetrically excite the coaxial horn; the present invention can realize the radiation characteristics of a dual-band dual-conical beam, effectively improving the detection range of the antenna; the filtering function is integrated in the high-frequency filtering and feeding module, effectively improving the anti-interference capability of the antenna; and at the same time, it has high power capacity and radiation efficiency.

The utility model provides a feed source assembly and a parabolic antenna, and the feed source assembly comprises a housing which is provided with an accommodation cavity; the reflecting plate is arranged on the shell and is accommodated in the accommodating cavity; the vibrator is arranged on the reflecting plate and is accommodated in the accommodating cavity; the supporting tube is arranged on the shell, the supporting tube and the vibrator are distributed at intervals, the supporting tube is provided with a wire passing channel communicated with the containing cavity, and the wire passing channel is used for a coaxial cable to penetrate through so that the two ends of the coaxial cable can be connected with the vibrator and the signal source respectively; the connecting disc is arranged at one end, far away from the shell, of the supporting pipe, and the connecting disc is used for being connected with a supporting frame of the parabolic antenna; and the coaxial cable penetrates through the wire passing channel and is connected with the vibrator, and the coaxial cable is used for being connected with a signal source. Signals of the feed source assembly are transmitted through a coaxial cable instead of a circular waveguide, so that the diameter of the supporting tube is smaller than that of the circular waveguide. Moreover, the diameter of the supporting tube is far smaller than the diameter of a circular waveguide which has the same frequency and is used for transmitting microwave signals, so that the size of the feed source assembly is greatly reduced, the loss of electrical performance can be reduced, and the weight of the parabolic antenna is reduced.

The invention discloses a photoacoustic sensing unit, an acoustic signal detection device and an acoustic signal detection method, and relates to the technical field of acoustic detection. The lower wrapping layer is arranged on the upper surface of the substrate, and a mounting groove is formed in the lower wrapping layer; the core layer is arranged in the mounting groove, the core layer comprises a straight waveguide and a circular waveguide, and a coupling distance is formed between the straight waveguide and the circular waveguide; the straight waveguide, the circular waveguide and the coupling space jointly form a light field regulation and control area; the exposed area covers the core layer and the lower wrapping layer, the exposed area comprises a groove, and the sensitive medium packaging layer is used for receiving sound pressure signals, generating corresponding deformation and transmitting the deformation to the core layer to cause the structure or state change of the light field regulation and control area, so that the effective refractive index of the circular waveguide is changed, and the sound pressure signal is generated. The change of the effective refractive index causes the drift of the harmonic peak wavelength, and the variation of the sound pressure signal is determined according to the displacement of the harmonic peak wavelength. The sensitivity of sound pressure detection is improved.

This invention provides a Ka / V band dual-frequency conical beam antenna for millimeter-wave detection, comprising an upper square metal structure, a lower square metal structure, a coaxial waveguide, an open circular waveguide, and a feed network. The open circular waveguide is the main radiating part, transitioning from the coaxial waveguide to the open circular waveguide, allowing the open circular waveguide to operate in TM mode to generate a radially symmetrical electric field distribution. By adjusting the size of the open circular waveguide, TM01 and TM02 modes exist within it, respectively generating Ka / V band electromagnetic waves. This invention utilizes a shielded microstrip line to excite the fundamental TEM mode of the coaxial waveguide before transitioning to the TM mode of the circular waveguide, which can suppress other unwanted modes, thereby making the omnidirectional radiation of the antenna more uniform. The coaxial waveguide is a stepped coaxial waveguide with varying radius. The stepped structure of the waveguide inner diameter can achieve good impedance matching. The structure is simple, easy to implement, and has dual-frequency, dual-tilt radiation characteristics.

This invention discloses a method for operating in a circular waveguide TE 11 This invention relates to a millimeter-wave high-power rotating reflective waveguide phase shifter, belonging to the field of millimeter-wave transmission technology. It comprises a rectangular waveguide wide-side slot 3dB coupler, a rectangular-circular waveguide transition section, and a rotating circular waveguide phase shifting section, with its central plane divided into two symmetrical microwave channels. Electromagnetic waves are first injected through the first port of the rectangular waveguide wide-side slot 3dB coupler, then split into two paths entering the rectangular-circular waveguide transition section through the third and fourth ports of the coupler, and subsequently injected into the rotating circular waveguide phase shifting section. After propagating a certain distance within the two phase shifting waveguides, the waves are reflected by a rotating metal plate piston and finally output from the second port of the rectangular waveguide wide-side slot 3dB coupler. This invention modulates the phase at the output end by changing the electrical length of the electromagnetic wave propagating within the phase shifting section by rotating the position of the metal plate piston. Within the same operating frequency band, it possesses advantages such as high power capacity, compact structure, high phase shifting accuracy, and a large phase shifting range.

This invention relates to a high-efficiency and compact hollow circular waveguide mode purifier, comprising five parts: a main waveguide, an input waveguide, a spherical waveguide, a re-entry resonant cavity, and an output waveguide; this invention can maintain high TM over a wide bandwidth. 01 TM 02 - TM 01 The mode conversion efficiency is high, which can effectively adapt to application environments with various mode compositions. This invention adopts a spherical corrugated waveguide and a re-entry resonant cavity, which has a simple structure and compact axial length, providing a feasible technical route for achieving compact mode purification.

The circular polarizer (100) includes a circular waveguide (10) having an inner peripheral surface (10a) with a circular opening cross section, and an iris (23) having an elliptical inner peripheral surface (23a) protruding from the inner peripheral surface (10a) toward the tube axis (C) of the circular waveguide (10), thereby forming an elliptical opening cross section. The irises (23) are periodically arranged in the tube axis direction.

The application discloses a terahertz optical fiber-space mode adapter, which comprises an antenna, a rectangular waveguide, a power divider, a mode converter, a circular waveguide and a transition horn; the antenna is connected with the rectangular waveguide; the power divider is connected with the rectangular waveguide, and an output port is connected with an input port of the mode converter; the mode converter is provided with a plurality of output ports and is arranged on the circular waveguide in a circumferential symmetry mode; the transition horn is connected with the circular waveguide; the antenna is used for receiving a space electromagnetic wave and feeding the space electromagnetic wave into the rectangular waveguide; the rectangular waveguide is used for transmitting a TE10 mode; the mode converter is used for converting the TE10 mode into a TE01 mode in the circular waveguide; and the circular waveguide is used for propagating the TE01 mode to the transition horn and filtering a terahertz wave of an unwanted mode. The adapter provided by the application can receive a space electromagnetic wave through the antenna, then generate a required high-purity electromagnetic mode through the mode converter, efficiently excite a required mode of an optical fiber, and avoid an impure excitation mode.

FIELD: antenna technology.SUBSTANCE: invention is intended for receiving and transmitting electromagnetic waves as part of reflector antennas. A dual-band reflector antenna feed is proposed, consisting of a circular waveguide, a radiator with external corrugation, a counter-reflector located opposite the end of the circular waveguide, two dielectric inserts and a metal rod. The first dielectric insert is made in the form of a hollow cylinder, secured on one side in the groove of the counter-reflector, and on the other side in the groove of the emitter. The second dielectric insert is installed inside the emitter and secured on a metal rod, which is connected on the opposite side by a threaded connection to the counter-reflector.EFFECT: increase in the level of matching of the antenna system with the load.1 cl, 3 dwg

The application discloses a relativistic magnetron with an energy feedback structure and belongs to the microwave technical field.The relativistic magnetron is a full-cavity extraction structure and comprises an anode, a cathode, an energy extraction structure and a guide magnetic field coil; wherein the energy extraction structure is provided with a ring-shaped microwave reflection plate in an output circular waveguide part, part of energy is reflected back to a cathode-anode gap, the interaction between an electron cloud and a space electromagnetic wave is enhanced, and the output power of the relativistic magnetron is improved. The application effectively improves the output power of the relativistic magnetron while guaranteeing the compactness of the device; meanwhile, the energy feedback structure is simple and easy to process.

The present invention belongs to the field of high-power microwave technology and discloses a high-power microwave circular waveguide TM01-TE11 mode converter, which is mainly composed of an input circular waveguide, a rectangular waveguide, and an output circular waveguide in cascade. The central axes of the input circular waveguide and the output circular waveguide are in the same position, and the device ports are coaxial. The rectangular waveguide is short-circuited at both ends, and the length of the two short-circuit surfaces from the central axis of the system differs by a quarter of the waveguide wavelength. The waveguide walls where the wide sides are located are respectively provided with an input interface and an output interface, the input interface is connected to the input circular waveguide, and the output interface is connected to the output circular waveguide. In order to reduce the circular waveguide TE11 reflection mode, two metal plates are radially arranged inside the input circular waveguide. The present invention realizes the conversion of the circular waveguide TM01 mode to the circular waveguide TE11 mode, has the advantages of easy processing, compact structure, and coaxial center of the input port and output port, and can be applied to high-power microwave systems.

The invention discloses a compact 90-degree over-mode waveguide TE01-TM11 mode converter, and belongs to the technical field of microwaves and millimeter waves. The mode converter comprises a first transition section, an over-mode corrugated groove turning section, an over-mode smooth mode conversion section and a second transition section which are connected in sequence, and the joints of inner cavities of the sections are in smooth transition; the over-mode corrugated groove turning section is formed by periodically arranging a plurality of circular ring grooves on the inner wall of the smooth over-mode circular waveguide, and the turning angle is the turning radius R; and the turning angle of the over-mode smooth mode conversion section is the turning radius R. While 90-degree turning is realized, the working mode is converted from the TE01 mode to the TM11 mode, and meanwhile, the waveguide mode converter has the functions of a waveguide mode converter and an elbow, so that the use of transmission devices is reduced, and the efficiency of the whole system is improved.

A rotatable circular waveguide structure is described that may include a circular waveguide segment configured to propagate electromagnetic radiation. The circular waveguide segment may enable transmission of data signals between portions of an electronic device, such as a chassis portion and a display portion, which may be rotatable relative to each other. The rotatable circular waveguide structure may include one or more circular waveguide segments routed through a hinge of the electronic device, and one or more rotatable junction points. The rotatable junction enables rotation of the circular waveguide segments relative to each other when the coupling portion of the electronic device is also rotated. The rotatable circular waveguide structure may replace the use of a data cable conventionally used to carry data signals between portions of an electronic device.

The objective is to provide a wideband mode converter that can convert an input in TE10 mode, used in rectangular waveguides, etc., to an output in TM01 mode, used in circular waveguides, etc. [Solution] The mode converter includes an input unit, a first rectangular output unit, and a second rectangular output unit, and comprises an inverse phase conversion unit that converts the TE10 mode electromagnetic wave input to the input unit into two electromagnetic waves with a phase difference of 180° from each other and outputs them to the first rectangular output unit and the second rectangular output unit, a first semicircular output unit connected to the first rectangular output unit and equipped with a first semicircular output unit, a second semicircular output unit connected to the second rectangular output unit and equipped with a second semicircular output unit, and a TM01 mode generation unit connected to the first semicircular output unit and the second semicircular output unit that generates the TM01 mode and outputs it to the circular output unit.

The invention discloses a compact broadband circular waveguide TM01 mode bending structure, and aims to solve the technical bottleneck that an existing circular waveguide TM01 mode bending structure is difficult to consider the aspects of bandwidth, structural compactness and power capacity at the same time. The antenna is composed of two circular waveguide TM01 mode power dividers, two E-plane U-shaped folded waveguide arrays and two E-plane rectangular bent waveguide arrays. The coaxial waveguide TEM mode and the multi-path rectangular waveguide TE10 mode are adopted as the middle transition mode of the antenna, and the problem of mode competition in a traditional bending structure is effectively solved. Meanwhile, by utilizing an E-plane U-shaped folded waveguide phase compensation technology, the length of each rectangular waveguide transmission path between the two circular waveguide TM01 mode power dividers is ensured to be consistent, the relative working bandwidth of which the transmission efficiency of a bent structure is greater than 95% is widened to be more than 40%, the power capacity is improved to the GW magnitude, and the distance between input / output ports is shortened to be within 5 times of the central wavelength.

Embodiments described herein relate to an apparatus that includes a microwave power generator, and a rectangular waveguide coupled to the microwave power generator. In an embodiment, the apparatus may also include an impedance tuner that is coupled to the rectangular waveguide, and a coaxial waveguide that is coupled to the rectangular waveguide. In an embodiment, the coaxial waveguide includes a conductive pin with a first end and a second end. In an embodiment, the apparatus further includes a circular waveguide cavity around the second end of the conductive pin, and a slotted antenna in the circular waveguide cavity.