Average Power Handling Capability Research Articles

Simulation and Measurement of an Interaction Structure With Distributed Radiation Coupling Circuit for a High-Power Ku-Band Gyro-TWT

Design and measurement of a distributed radiation coupling (DRC) circuit for the Ku -band TE11-mode gyrotron traveling wave tube (gyro-TWT) amplifier are presented. Different from the dielectric-loaded (DL) waveguide, the proposed DRC circuit can suppress the parasitic modes by achieving sufficient radiation coupling losses. It has the merit of lowering the microwave power loss density, which can improve the tube stability and average power-handling capability. Based on this proposed DRC circuit, a Ku -band TE11-mode gyro-TWT was designed and the particle-in-cell (PIC) simulation shows it can obtain a saturated output power of over 150 kW from 15.3 to 17.2 GHz for an electron beam with a velocity spread of 4.35%. As a comparison, the maximum average microwave power loss density is only 20% of the DL circuit under the same operating parameters. For verification, a DRC circuit was manufactured and cold tested. The maximum deviation between the measured results and our analysis is within 10%.

A Gysel Power Divider/Combiner with Enhanced Power-Handling Capability

By increasing the impedance of the microstrip of the combine port, a new Gysel power combiner/divider (PCD) with enhanced average power-handling capability (APHC) was proposed. This article shows the simulated results of the traditional Gysel PCD and the proposed Gysel PCD at the center frequency of 2.4 GHz and 10 GHz. For verification, one example of the proposed Gysel PCD operating at 2.4 GHz was designed, fabricated, and measured. One traditional Gysel PCD operating at 2.4 GHz was also fabricated to compare the APHC of the proposed Gysel PCD and the traditional Gysel PCD, by means of measuring the temperature variation of the microstrip line at the same power. The measurement result suggests the APHC of the proposed Gysel PCD is nearly twice that of the traditional Gysel PCD.

Average Power Handling Capability of Corrugated Slow-Wave Transmission Lines.

In this article, the average power handling capability (APHC) of corrugated slow-wave transmission lines (SWTLs) is investigated. Firstly, the attenuation constants of conductor and dielectric are extracted by the multiline method. Secondly, the thermal resistance of corrugated SWTLs is analyzed based on the constant-angle model. To deal with the non-uniform corrugated structure of SWTLs, the concept of average heat-spreading width (AHSW) is introduced. Finally, the APHC of the corrugated SWTL is calculated using the attenuation constant and the thermal resistance. In addition, the APHC considering the temperature-dependent resistivity of metal conductor is also presented. For validation, the APHCs of SWTLs with different geometric parameters are evaluated. The results agree well with those obtained by the commercial software.

An x‐band coplanar magic‐T with high power handing

AbstractAn x‐band coplanar magic‐T with high power handing is proposed by combining an H‐plane power divider and an iris for matching in E‐plane. The proposed magic‐T has −15 dB impedance bandwidth in experiment, which is about 23% covering form 8.9 to 11.2 GHz. Furthermore, the isolation is better than 46.2 dB with the typical insertion loss of 0.15 dB in the whole bandwidth with the contribute of the symmetrical structure. Herein, the average power‐handling capability (APHC) could be estimated at 865 W by simulated analysis, since the structure is all‐metal. Excellent correspondence between the simulated and measured results is demonstrated.

Average Power Handling Capability of Microstrip Lines Considering Heat Convection and Self-Heating Effects With Temperature-Dependent Resistivity

Average Power Handling Capability of Microstrip Lines Considering Heat Convection and Self-Heating Effects With Temperature-Dependent Resistivity

Design and Synthesis of Ferrite Strip-Line Circulator Based on Enhanced Closed Form Solution and Power Handling Analysis

In this article, Y-junction strip-line circulators are designed using an enhanced closed form solution consisting of unified key equations and a flowchart design, which serves as a direct procedure for designing a ferrite circulator. This design methodology is combined with a 3D EM simulation that allows for the calculation of the saturation magnetization, uniform biasing, and ferrite dimensions needed for a circulator to operate in both modes. In addition, the closed form can be used to calculate the Y-junction parameters and allow the matching network to be calculated and the uniform circulator biasing design ended. Our analysis starts with the ferrite calculation to ensure that it is uniformly biased magnetically, and this is followed by strip-line design, Y-junction matching, and biasing circuit design. Using full-wave electromagnetic (EM), HFSS and magnetostatic (MS), Maxwell3D simulations, several key design parameters such as the saturation magnetization, coupling angle, and various external permanent magnetic biases are investigated. To validate the proposed concept, two strip-line circulators are designed and fabricated for operation in wide-bandwidth and narrow-bandwidth applications. Good agreement is found between the simulated and experimental responses for the S-parameters of the circulators. We also present a semi-analytical analysis of the concept of breakdown, which enables calculation of the peak power and total thermal rise in the strip-line structure. The average power handling capability of a strip-line circulator is studied for the first time. The proposed closed form expressions can also be implemented in various ferrite circulators using different guiding technologies for millimeter-wave applications.

Development of high power 20 dB directional coupler for Ion Cyclotron Resonance frequency system of Tokamak

This article presents the design and fabrication of 20± 0.3dB directional coupler having 2kW power handling capability in the frequency range of 140-200MHz. The developed coupler has an important application in the prototype of the Ion Cyclotron Resonance Frequency (ICRF) system of Tokamak. The directional coupler used to couple the forward and reflected power for measurement and provide the feedback to the existing matching network responsible for protecting the high power RF source. The prototype ICRF system has been developed to test the matching speed of the ICRF system for load resilient operation. The developed coupler is compact in size, robust, and capable of handling 2kW, continuous wave (cw) RF power. This paper also analyses the dielectric breakdown strength using electric field distribution inside the coupler and the average power handling capability is determined using numerical analysis. The test and simulation results of developed coupler are found in good agreement. The test results using Vector Network Analyzer (VNA) are obtained as, the coupling flatness of 20 ± 0.3 in 140-200 MHz frequency range, return loss and isolation are -30dB and -35dB respectively. The work presented in this paper is helpful for the design and development of high power coupler in radio frequency (RF) range and may be applied in various applications such as RF Plasma, Radar, navigation, satellite and research etc.

Broadband and High Power Meta-Surface Dielectric Window for W-Band Gyrotron Traveling Wave Tubes

A periodic dielectric meta-surface output window was cold and hot tested to extend the operating bandwidth and suppress the parasitic oscillations for a W-band wideband TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode gyrotron traveling wave tube (gyro-TWT) in this letter. The fabricated beryllium oxide meta-surface dielectric window demonstrates a relative bandwidth of 37.84% with the reflection below −20 dB in the range of 75–110 GHz. The influences of engineering factors and machining errors on the performance are investigated and analyzed. Thermal analysis shows the average power handling capability of the window is over 33 kW within a wide frequency range. Hot test results demonstrate that the meta-surface window is excellent for oscillation suppression and the power handling capability is predicted larger than 20 kW.

A 3-D Printed $E$ -Plane Waveguide Magic-T Using Air-Filled Coax-to-Waveguide Transitions

This article reports on a new class of broadband and fully 3-D printed $E$ -plane coax-to-waveguide transition and a monolithically 3-D printed waveguide magic-T based on the transition. The transition is constructed by a section of air-filled rectangular coaxial transmission line (TL) that is placed between two broadband coax-to-waveguide probe transitions. It is used to interconnect the magic-T’s sum port and the waveguide T-junction. The incorporation of the transition reorients all the waveguide arms of the magic-T into the $E$ -plane. Some $X$ -band prototypes of the proposed transition and the magic-T are designed and implemented. Polymer-based additive manufacturing and copper electroplating techniques are employed to monolithically fabricate each prototype. The transition and the magic-T exhibit broadband and low-loss characteristics from 8.2 to 12.4 GHz with the measured performance well matched with the simulations. In addition, the power handling capability (PHC), including the peak PHC (PPHC) and the average PHC (APHC), of the magic-T is evaluated by simulations, showing that the proposed magic-T could handle 100 W of APHC.

Average power handling capability on SiON thin film coplanar waveguide interconnections for MMICs

In this study, we investigated the average power handling capability (APHC) of silicon-oxy-nitride (SiON) thin-film-coated coplanar waveguide (CPW) interconnections for monolithic microwave integrated circuits (MMICs). SiON thin films were prepared through very-high-frequency plasma-enhanced chemical vapor deposition at 40.68 MHz. Films prepared under various annealing conditions were studied. The microwave characteristics of CPW interconnections were analyzed for fitting to the International Technology Roadmap for Semiconductors. SiON thin films were annealed under a vacuum condition for 60 s at 700 °C, 900 °C and 1100 °C. The use of coated and annealed SiON thin films on the low-resistivity Si substrate effectively improved the substrate resistivity, reduced microwave attenuation at 1100 °C, and enhanced the APHC of CPW interconnections. These results indicate that the proposed method is suitable for application to MMICs.

Peak and Average Power Handling Capability of Microstrip Filters

In this paper, the power handling capability of microstrip filters is studied in detail. This paper is addressed from two perspectives, depending on the physical phenomenon limiting the maximum power that the microstrip filter can handle. One of these phenomena is air breakdown or corona effect, which is linked to the peak power handling capability (PPHC) of the device, and the other is the self-heating, which limits the device average power handling capability (APHC). The analysis is focused on three kinds of filtering topologies widely used both in academia and industry, such as the coupled-line, stepped impedance resonator and the dual-behavior resonator-based filters. Closed-form expressions are computed to predict both the PPHC and the APHC as a function of the geometrical parameters of the resonators integrating the filter. Guidelines are also given to extrapolate the provided computations to other filtering topologies based on other kinds of resonators. To validate this research study, three bandpass filters centered at 5 GHz have been implemented and fully characterized by means of two measurements campaigns which have been carried out, one for the PPHC and another one for the APHC. The measured results have validated the performed study and corroborated the conclusions obtained throughout this paper.

Microwave Characteristics of Thin-Film Passivation on Ceramic Substrate by Using DC Reactive Magnetron Sputtering

This paper presents a novel method to change the dielectric constant and enhance the average power-handling capability (APHC) to a thin-film coplanar waveguide (CPW) line through dc reactive magnetron sputtering. This paper discusses the effects of material properties, microwave characteristics, and APHC on the thin-film CPW line. An aluminum nitride (AlN) thin film can be deposited on the surface of a ceramic substrate to provide a substrate with a smooth surface. Using the proposed thin-film passivation on the ceramic substrate can effectively improve the thermal conductivity and enhance the APHC of a thin-film CPW line. In a physical experiment, a thin-film CPW line with a 3- $\mu \text{m}$ -thick AlN thin film was deposited on a 1000- $\mu \text{m}$ -thick ceramic substrate. Microwave losses (including conductor loss $\alpha _{c}(f)$ and dielectric loss $\alpha _{d}(f)$ ) dielectric constant and APHC were extracted from S-parameters that were measured up to 10 GHz. The method can be applied in ceramic fabrication processes, particularly in low-temperature cofired ceramic techniques.

A Shared-Aperture Helical-Array Antenna Set at L and S Bands for Navigation Satellite Systems [Antenna Applications Corner

This article reports on the design and development of a novel sharedaperture antenna that is set at the widely separated L5 and S bands for navigation satellite systems with its concentric phase centers located at the two bands. The design of the radiating element and its performance is also detailed as well as the design of the critical sections, namely, the square-coaxialline and waveguide feed networks, in view of multipaction and average power handling capability. An innovative method of implementing a sequential rotation scheme for improving the array cross-polarization isolation is discussed, and, subsequently, this article also presents and compares the measured and analyzed results of the array antenna set at the L5 and S bands. After data analysis, it was found that the in-orbit test results of the antenna well agreed with its measured results acquired at the ground level.

Air-Filled Substrate Integrated Waveguide for Low-Loss and High Power-Handling Millimeter-Wave Substrate Integrated Circuits

An air-filled substrate integrated waveguide (SIW) made of a multilayer printed circuit board process is proposed in this paper. It is of particular interest for millimeter-wave applications that generally require low cost and low-loss performance and excellent power-handling capability. This three-layered air-filled SIW allows for substantial loss reduction and power-handling capability enhancement. The top and bottom layers may make use of a low-cost standard substrate such as FR-4 on which baseband or digital circuits can be implemented so to obtain a very compact, high-performance, low-cost, and self-packaged millimeter-wave integrated system. Over Ka-band (U-band), it is shown that the air-filled SIW compared to its dielectric-filled counterparts based on Rogers substrates RT/Duroid 5880 and also 6002 reduces losses by a mean value of 0.068 dB/cm (0.098 dB/cm) and 0.104 dB/cm (0.152 dB/cm), increases average power-handling capability by 8 dB (6 dB) and 7.5 dB (5.7 dB), and quality factor by 2.7 (2.8) and 3.6 (3.8) times, respectively. The peak power-handling capability of the proposed structure is also studied. A wideband transition is presented to facilitate interconnects of the proposed air-filled SIW with dielectric-filled SIW. Design steps of this transition are detailed and its bandwidth limitation due to fabrication tolerances is theoretically examined and established. For validation purposes, a back-to-back transition operating over the Ka-band is fabricated. It achieves a return loss of better than 15 dB and an insertion loss of 0.6 ±0.2 dB ( 0.3 ±0.1 dB for the transition) from 27 to 40 GHz. Finally, two elementary circuits, namely, the T-junction and 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> hybrid coupler based on the air-filled SIW, are also demonstrated.

Average Power Handling Capability of Microstrip Passive Circuits Considering Metal Housing and Environment Conditions

In this paper, the average power handling capability (APHC) of microstrip passive circuits considering the metal housing and environment conditions is investigated in detail. A systematic method is proposed for the computation of the APHC of microstrip circuits in open and enclosed metal housing configurations, typically used in microwave components. The method also yields an estimate of the maximum temperature in a microstrip circuit for a given input power. Closed-form equations accounting for external conditions, such as convection or radiation heat transfer are given to evaluate the APHC. For validation, two microstrip bandstop filters centered at 10 GHz are analyzed following the proposed model, and the results are compared with those simulated showing a good agreement. In addition, both circuits are fabricated and characterized. Thermal profile measurements are provided, confirming the predicted results. The effect of the topology layout and the electromagnetic performance on the APHC are also discussed.

Thermal behaviour of a periodic structure supported by dielectric rods in vacuum

In a traveling-wave tube (TWT) the helical periodic slow-wave structure (SWS) is supported by dielectric supports in a metal envelope in high vacuum. The heat generated in the helix during beam-wave interaction, restricts the average power handling capability of a TWT, dissipated by conduction through support rods. Thermal contact resistances, arises at different joints of different materials, affect heat dissipation from the helix which have been studied and presented here.

Average power handling capability of thin‐film microstrip line under dc‐bias conditions

AbstractAverage power handling capability (APHC) of the thin‐film microstrip line (TFML) under dc‐bias conditions (&lt;1 V) is proposed for the first time. The TFMLs with a 20‐μm‐thick polyimide thin films are fabricated on a low‐resistivity silicon substrate (ρ ≤ 10 Ω cm). Losses and APHC are extracted from the measured S‐parameters up to 50 GHz. This study has also been studied on the different roughness and thermal conductivity of the polyimide film to evaluate the APHC of the dc‐biased TFML. It is believed that the evaluations are useful for the high‐dense microwave monolithic integrated circuits. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:84–87, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25653

Characterization of Average Power Handling Capability of Bandpass Filters Using Planar Half-Wavelength Microstrip Resonators

Several closed-form equations are obtained for characterizing the average power handling capability (APHC) of bandpass filters (BPFs) using planar half-wavelength open-circuited microstrip resonators. It is found that the temperature rise (TR) of the BPF is the product of two terms corresponding to the single microstrip resonator and the filter, respectively. The APHC of an eighth-order open-loop BPF is determined numerically, with good agreements obtained between its maximum TRs calculated using our model and 3-D-FEM software.

Femtosecond Yb-fiber chirped-pulse-amplification system based on chirped-volume Bragg gratings

A 100 W amplified (75 W compressed) femtosecond (650 fs) Yb-fiber chirped-pulse-amplification system is demonstrated using broadband chirped-volume Bragg gratings (CVBGs) for the stretcher and compressor. With a 75% compression efficiency, the CVBG-based compressor exhibits an excellent average power handling capability and indicates the potential for further power scaling with this compact and robust technology.

Power Handling Capability of Substrate Integrated Waveguide Interconnects and Related Transmission Line Systems

As a novel interconnect and planar transmission line structure, the substrate integrated waveguide (SIW) is investigated in terms of its power handling capabilities (PHCs) including average and peak power handling capabilities. A heat transfer analysis based on ohmic and dielectric attenuation of SIW has been used to calculate the average power handling capability (APHC) while the maximum E-field derivation method has been selected to determine the peak power handling capability (PPHC). Results from the present investigations have shed light on some basic properties of SIW interconnects and related transmission line systems in a high-power operating environment and also can be used to analyze some application-oriented structures such as SIW bends. It is believed from the conclusions that an SIW interconnect can handle medium average power with extremely high peak power over microwave and millimeter-wave frequency bands.