Microstrip Meander-line Slow-wave Structure Research Articles

Investigation and Fabrication of the Printed Microstrip Meander-Line Slow-Wave Structures for D-Band Traveling Wave Tubes

Two typical topology shapes of the microstrip meander line (MML) including round U-shaped and V-shaped slow-wave structure (SWS) for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D}$ </tex-math></inline-formula> -band traveling wave tubes (TWTs) are comparatively investigated, fabricated, and tested in this article. As a critical factor applied in millimeter-wave frequency, the high-frequency losses of the MML SWS are emphatically discussed. The two types of golden SWSs are both fabricated with the thin-film circuit technology on quartz substrates. After the surface roughness test and the cavity fabrication, the SWS samples are assembled and tested. According to the experimental test results, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{11}$ </tex-math></inline-formula> parameters of the U-shaped and V-shaped transmission models are below −13.5 dB versus −15 dB, and the “cold” <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{21}$ </tex-math></inline-formula> parameters are over −6.4 dB versus −4.9 dB, which are approached to the simulation results with the consideration of the silver conductive paste (SCP). At 140 GHz, the tested transmission losses for the U-shaped SWS and V-shaped SWS are about 0.35 and 0.29 dB/mm, respectively. Although particle-in-cell (PIC) simulations for the two SWSs both predict more than 100-W output power, the V-shaped MML TWT shows better bandwidth and loss performances than the U-shaped MML TWT.

Inverse Design of a Microstrip Meander Line Slow Wave Structure with XGBoost and Neural Network

We present a new machine learning (ML) deep learning (DL) synthesis algorithm for the design of a microstrip meander line (MML) slow wave structure (SWS). Exact numerical simulation data are used in the training of our network as a form of supervised learning. The learning results show that the training mean squared error is as low as 5.23 × 10−2 when using 900 sets of data. When the desired performance is reached, workable geometry parameters can be obtained by this algorithm. A D-band MML SWS with 20 GHz bandwidth at 160 GHz center frequency is then designed using the auto-design neural network (ADNN). A cold test shows that its phase velocity varies by 0.005 c, and the transmission rate of a 50-period SWS is greater than −5 dB with the reflectivity below −15 dB when the frequency is from 150 to 170 GHz. Particle-in-cell (PIC) simulation also illustrates that a maximum power of 3.2 W is reached at 160 GHz with 34.66 dB gain and output power greater than 1 W from 152 to 168 GHz.

Meander-Line Slow-Wave Structure on Dielectric Substrate for a Millimeter-Band Traveling-Wave Tube

A novel planar microstrip meander-line slow-wave structure (SWS) on dielectric substrate for a miniature low-voltage millimeter-band traveling-wave tube (TWT) with a high-aspect-ratio sheet electron beam is proposed. Main electromagnetic parameters of the SWS were studied. Using of such a slow-wave structure may lead to increase of the gain and output power of the TWT amplifier.

Замедляющая система меандрового типа на диэлектрической подложке для лампы бегущей волны миллиметрового диапазона

А novel planar microstrip meander-line slow-wave structure (SWS) on dielectric substrate for a miniature low-voltage millimeter-band traveling-wave tube (TWT) with a high-aspect-ratio sheet electron beam is proposed. Main electromagnetic parameters of the SWS were studied. Using of such a slow-wave structure may lead to increase of the gain and output power of the TWT-amplifier

On-Wafer Microstrip Meander-Line Slow-Wave Structure at Ka-Band

A novel configuration for a Ka-band V-shaped microstrip meander-line slow-wave structure (SWS) is reported. The SWS is designed to work at a voltage less than 4 kV and provide a wide bandwidth. Coplanar waveguide (CPW) input–output feed lines and a shielding structure are incorporated to enable fast on-wafer cold test measurements on a CPW probe station without requiring dicing or a metal enclosure. Simulated dispersion characteristics and coupling impedance for the optimized design are presented. The simulated S11 of the entire structure is better than −15 dB over 25–36 GHz. The proposed configuration is fabricated using $4^{\prime \prime }$ Si wafers and standard microfabrication processes. The measured S11 of the entire structure is better than −10 dB over 20–40 GHz. The observed high insertion loss has been explained in detail, and alternative approaches that can reduce the loss have been proposed. The PIC simulation results show that for a 3.6-kV, 50-mA sheet beam, the output power can potentially reach 14.5 W at 34 GHz with a gain of 21.6 dB. A 3-dB bandwidth of about 25% centered at 32 GHz is also indicated.

Integrated Microstrip Meander Line Traveling Wave Tube Based on Metamaterial Absorber

An integrated microstrip meander line (MML) slow-wave structure (SWS) comprised of an MML SWS and compact wideband metamaterial absorber (MMA) is proposed and demonstrated theoretically and experimentally in this paper. The MMA consists of metallic rectangular resonators with a metallic ground plane and a separating dielectric layer. Simulation results show that the MMA has multidistinctive absorption peaks; the bandwidth at 56-GHz peak frequency is reach up to 30 GHz. The integrated MML SWS can provide flatter gain response of output power than that made by the MML SWS with a traditional resistive coating attenuator. Experimental results are in close agreement with simulation results. A traveling wave tube (TWT) is simulated based on this integrated MML SWS. The output power of this TWT is 48.21 W at 33 GHz corresponding to a maximum gain of 30.3 dB; the output power gain is greater than 25 dB across the entire working frequency range.

A Novel Winding Microstrip Meander-Line Slow-Wave Structure for V-Band TWT

A novel winding microstrip meander-line slow-wave structure (SWS) has been proposed to develop low-voltage and high-power millimeter-wave traveling-wave tube. This structure, which interacts with a round electron beam, evolves from a V-shaped microstrip meander-line SWS. The electromagnetic characteristics and beam-wave interaction of this novel structure are calculated in this letter. As is seen from the results, traveling-wave tubes with this novel circuit can provide over 130-W output power ranging from 58 to 63 GHz. In addition, the maximum electronic efficiency may reach 10% at 61 GHz.

A 3-D U-Shaped Meander-Line Slow-Wave Structure for Traveling-Wave-Tube Applications

A novel 3-D U-shaped meander-line (ML) slow-wave structure (SWS) is proposed for traveling-wave-tube applications. This 3-D structure has the potential to have a better performance than the corresponding 2-D ML SWSs proposed in the literature. Simulation results at S-band obtained using CST Microwave Studio are presented to compare the phase velocity, interaction impedance, and circuit attenuation of the proposed structure with those of a recently reported symmetric double V-shaped microstrip ML SWS, showing advantages with respect to circuit attenuation, bandwidth, and feed design. Particle-in-cell simulations are also carried out for the proposed structure for a cylindrical electron beam using CST Particle Studio. The saturated gain and electronic efficiency of the 3-D U-shaped ML SWS is significantly higher than that of the symmetric double V-shaped ML SWS. The proposed structure has been designed and fabricated with a microstrip-line feed at S-band. The measured return loss, phase velocity, and circuit attenuation match well with the simulation results. By using microfabrication techniques, the proposed SWS has the potential to operate at millimeter-wave and higher frequencies.

Effect of Structural Parameters on High Frequency Characteristics of Microstrip Meander-Line Slow Wave Circuit

A novel V-shaped microstrip meander-line slow-wave structure was investigated to expand the operating bandwidth. The high frequency characteristics of V-shaped structure and traditional N-shaped and U-shaped structures were analyzed by electromagnetic simulation software HFSS, and the effects of different structural parameters on the high frequency characteristics were studied. The results show that the V-shaped structure provides better performance in operation bandwidth and interaction impedance than traditional structures, and when the dielectric rod replaces the dielectric slab the performance further improves.

Study on a W-band modified V-shaped microstrip meander-line traveling-wave tube

The study on a miniaturized, low-voltage, wide-bandwidth, high-efficiency modified V-shaped microstrip meander-line slow-wave structure is presented. This structure is evolved from the original U-shaped microstrip meander-line slow-wave structure, combining the advantages of a traditional microstrip and a rectangular helix. In this paper, simulations of the electromagnetic characteristics and the beam-wave interaction of this structure are carried out. Our study shows that when the design voltage and the current of a sheet electron beam are set to be 4700 V and 100 mA, respectively, this miniature millimeter-wave power amplifier is capable of delivering 160-W output power with a corresponding gain of 37.3 dB and a maximum interaction efficiency of 34% at 97 GHz.

Symmetric Double V-Shaped Microstrip Meander-Line Slow-Wave Structure for W-Band Traveling-Wave Tube

A design study for a low-voltage, high-efficiency, and wide-bandwidth W-band traveling-wave tube using a symmetric double V-shaped microstrip meander-line slow-wave structure combined with a sheet electron beam is described in this paper. The electromagnetic characteristics including the dispersion characteristics, interaction impedance, and transmission characteristics of this structure are presented, and the beam-wave interaction is calculated using particle-in-cell algorithms. Our study shows that, when the design voltage and current of the sheet electron beam are set to 4570 V and 100 mA, respectively, this miniature millimeter-wave power amplifier is capable of delivering several tens of watts output power, and the peak output power is about 110 W with a corresponding gain of 31.4 dB and an averaged electronic efficiency of 12% at 94 GHz.

A Novel V-Shaped Microstrip Meander-Line Slow-Wave Structure for W-band MMPM

In this paper, a novel V-shaped microstrip meander-line slow-wave structure (SWS) is proposed for use in a low-voltage high-efficiency wide-bandwidth miniature millimeter-wave traveling-wave tube (TWT). The electromagnetic characteristics and the interaction between the sheet electron beam and slow wave in this SWS are obtained by utilizing the CST Microwave Studio and Particle Studio codes, respectively. From our calculations, it is predicted that, at a beam voltage of 3.7 kV and a beam current of 100 mA, an output power greater than 30 W can be obtained ranging from 75 to 100 GHz, and this V-shaped microstrip meander-line TWT will be helpful for a W-band millimeter-wave power module.

140 GHz菱形微带曲折线慢波结构行波管的模拟计算

A rhombus-shaped microstrip meander-line slow-wave structure is proposed for use in a low voltage, wide bandwidth, moderate power and high efficiency millimeter-wave traveling-wave tube. The structure is evolved from the original V-shaped microstrip meander-line slow-wave structure. Compared with the conventional slow-wave structure, it is a kind of planar structure, whose fabrication can be easily realized by utilizing the technology of 2-D micro-fabrication. Whats more, the structure can realize beam-wave interaction with sheet electron beam, and no additional electron beam channel is needed. The electromagnetic characteristics and the interaction between the sheet electron beam and slow wave in the structure are obtained by utilizing the electromagnetic simulation software HFSS and the particle-in-cell code in CST Particle Studio, respectively. Our calculations indicate that, at a beam voltage of 7 kV and a beam current of 90 mA, the traveling wave tube based on the structure is capable of delivering several tens of watts output power with an interaction efficiency of 14.3％ and a transient 3 dB bandwidth of 18 GHz(ranging from 132 GHz to 150 GHz)

140-GHz V-Shaped Microstrip Meander-Line Traveling Wave Tube

A study on a miniature, low voltage, wide bandwidth, and high RF efficiency V-shaped microstrip meander-line slow-wave structure is carried out in this paper. The fabrication of this structure is very convenient by utilizing the 2-D micro-fabrication techniques. Radio-frequency characteristics including dispersion properties, interaction impedance and S-parameters are analyzed. Based on these results, nonlinear large signal performances of the V-shaped microstrip meander-line traveling-wave tube are calculated by 3-D particle-in-cell code. This study shows that this miniature millimeter-wave power amplifier is capable of delivering several tens of watts output power ranging from 127 GHz to 145 GHz.

Dispersion and Field Analysis of a Microstrip Meander-Line Slow-Wave Structure

A structure which is important as an example of a spatially periodic medium for microwave propagation is analyzed theoretically, with rigorous consideration of its partial dielectric composition, symmetry properties; and field configuration relating to its use for electron-wave interaction in a crossed-field amplifier (CFA). The analysis is carried out in a quasi-TEM approximation, leading to determination of a complex potential function within the unit cell and the associated normal-mode parameters: effective dielectric constant, phase velocity, and characteristic impedance, as functions of phase per cell and mode symmetry. With imposition of meander-line boundary conditions, solutions of the characteristic equation for the dispersion law of the structure are computed, including the influence of the inhomogeneous dielectric-vacuum construction of microstrip. Agreement with the observed phase and stopband features of a representative structure is very good. Power distribution and group velocity are calculated, and an interaction impedance, representing the coupling between the RF field and an electron beam for estimation of CFA performance is also calculated. The method lends itself to detailed computations, including the effects of structural features of practical slow-wave circuits.