Stripline Design Research Articles

A 32-channel high-impedance honeycomb-shaped receive array for temporal lobes exploration at 11.7T.

The newly operational 11.7T Iseult scanner provides an improved global SNR in the human brain. This gain in SNR can be pushed even further locally by designing region-focused dense receive arrays. The temporal lobes are particularly interesting to neuroscientists as they are associated with language and concept recognition. Our main goal was to maximize the SNR in the temporal lobes and provide high-acceleration capabilities for fMRI studies. We designed and developed a 32-channel receive array made of non-overlapped hexagonal loops. The loops were arranged in a honeycomb pattern and targeted the temporal lobes. They were placed on a flexible neoprene cap closely fitting the head. A new stripline design with a high impedance was proposed and applied for the first time at 11.7T. Specific homebuilt miniaturized low-impedance preamplifiers were directly mounted on the loops, providing preamplifier decoupling in a compact and modular design. Using an anatomical phantom, we experimentally compared the SNR and parallel imaging performance of the region-focused cap to a 32-channel whole-brain receive array at 11.7T. The experimental results showed a 1.7-time higher SNR on average in the temporal lobes compared to the whole brain receive array. The g-factor is also improved when undersampling in the antero-posterior and head-foot directions. A significant SNR boost in the temporal lobes was demonstrated at 11.7T compared to the whole-brain receive array. The parallel imaging capabilities were also improved in the temporal lobes in some acceleration directions.

Study and Design of A Dual Mode Resonant Band-Pass Filter Suspended Substrate Stripline for 5G Communications

Study and Design of A Dual Mode Resonant Band-Pass Filter Suspended Substrate Stripline for 5G Communications

Design, Analysis and Validation of MCP Package for GaAs Monolithic Microwave Integrated Circuits Packaging

This paper describes the design aspects of high reliable packages including package resonance, material selection, and feed-through design to match the die designer specifications. Design, simulation and thin film fabrication of 50Ω microstrip line on a 10 mil Al2O3 substrate suitable for MMIC assembly are also presented. Al2O3 substrate is taken because of lower transitional losses at the seal ring of the package, lower leakage and best suitable for hermiticity. Strip line design, study and the input-output transitions between two ports is analysed and optimized. Evidence of package self resonating mode study carried out theoretically and similar is simulated by using CST microwave studio. Package physical model analysis is carried out on a metal-ceramic package (MCP) which is suitable for embedding an amplifier of 20 dB gain and low power in c-band, 35 dB gain and low noise figure in s-band and 28 dB typical gain in x-band. Packaging effects in each case is analysed and optimised to meet the design requirements. With systematic ideas, the complete package modelling, characterization and MMICs packaging are carried out as per the reliability standards for space application. This package is sealed using the hermetic sealing technique to assure no leakage when subjected to the environmental test conditions like operating temperature test, active burn-in test for 240 h and steady-state life test for 1000 h to check MMIC behaviour under overstress conditions. Packaged module RF performances are noted at pre-subjected and post-subjected temperature conditions. Drifts are calculated at both temperature stages.

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.

A novel 5-cell strip-line kicker prototype for the HEPS on-axis injection system

Two groups of 10ns-level superfast kickers are needed in the on-axis swap out injection scheme, adopted by the High Energy Photon Source (HEPS) to cope with the very small dynamic aperture of its baseline 7BA lattice design. In order to fit into the very tight longitudinal space in the injection/extraction region, and to relax the strength requirement of the kickers, five units of 300 mm long strip-line kickers are placed into a single stainless-steel vacuum chamber, to form a very compact 5-cell kicker module. Such a novel 5-cell strip-line kicker module design and its prototype development are presented in this paper. The results of the time-domain reflectometer (TDR) test, the high voltage pulse test and the beam coupling impedance test show that the strip-line kickers can meet the requirements of HEPS.

An improved strip-line fast Faraday cup for beam bunch measurements.

A 3 MeV proton radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A compact wide bandwidth strip-line fast Faraday cup (SFFC) has been developed for the beam bunch measurements of the 352 MHz RFQ. The SFFC design is improvised over the standard strip-line FFC designs with a thicker strip, which can withstand larger beam intensities. The absence of the pinhole beam limiting aperture and the provision for a suppressor electrode to suppress secondary electrons on the strip are other improvisations over standard SFFC designs. The SFFC has been characterized using the time domain reflectometry method, and a broad bandwidth of ∼7 GHz is measured. The SFFC has been tested with a 3 MeV RFQ beam at a 4 mA peak current. The time structure of the individual micro-pulses with a FWHM of 297 ps has been measured with a SFFC.

Comprehensive and Practical Way to Look at Far-End Crosstalk for Transmission Lines With Lossy Conductor and Dielectric

Far-end crosstalk (FEXT) noise is one of the major issues that limits signal integrity performance for high-speed digital products. It is important to estimate the crosstalk noise accurately to avoid noise margin failure or overdesigned transmission lines. Traditionally, analytical formulas for crosstalk noise are based on lossless and perfect impedance match assumptions, which provide limited guidance for a practical high-speed transmission line design. A phenomenon is observed that a lossy conductor increases the FEXT on coupled striplines. To provide a reasonable explanation, analytical and numerical investigations were performed using a modal analysis based approach. A new FEXT component due to the lossy conductor is proposed. Such FEXT component is important to a high-speed stripline design because it is a major contributor when all terminals are matched. To estimate the impact of loss on FEXT, a practical and fast estimation approach is proposed.

Design of a Wideband Surface Mountable Suspended Integrated Strip-Line Technology

This paper presents a low-loss surface mountable suspended integrated strip-line (SISL) technology. A DC-20 GHz thru transmission line and an eleventh-order generalized Chebyshev lowpass filter (LPF), with a cutoff frequency of 18 GHz, are simulated, fabricated, and measured to demonstrate the first-ever surface mountable suspended strip-line designs. Measured results of the thru line show less than 1 dB of insertion loss and greater than 10 dB of return loss across the 20 GHz bandwidth. Moreover, measured results of the LPF show less than 1 dB of insertion loss and greater than 10 dB return loss across the 18 GHz passband, as well as greater than 30 dB of suppression above 19 GHz. The proposed SMT SISL technology also has advantages of compact size, light-weight, low cost, and elimination of the extended circuit to be a multi-layer board following the trend to reduce the size, weight, power, and cost (SWaP-C).

Mechanical design of the high-powered helicon antenna and stripline feed in the DIII-D Tokamak

A high-powered “comb-line” helicon antenna for use within the DIII-D Tokamak is currently in design and fabrication at General Atomics. The antenna will drive current in high beta discharges using electromagnetic helicon waves. The high-powered helicon antenna (HPHA) is expected to couple up to one MW of power into DIII-D plasmas at a frequency of 476 MHz. The antenna design includes 30 individual, inductively coupled modules fastened to six internally water-cooled Inconel back-plates. The end modules have special design features to provide RF stripline feed attachment points. Each back-plate is mounted to a pedestal, which is secured to the vessel wall via a combination of studs and welded brackets. The mechanical design includes features to minimize and survive disruption forces, thermal loading from RF losses, vacuum vessel bake (350C), and installation considerations. Thermal stress design challenges include plasma heat loads, thermal ratcheting, and bake-out cycles that result in thermal growth differences between the stripline and the vessel. Splitting the back-plate into six sections each with a central pedestal support significantly reduces the disruption loads. A single stripline folded in half, fed near the fold provides a 180° phase shift between the stripline module connections for driving the two module straps. This looped mono RF coaxial stripline design was chosen to enable using one feed-through, to optimize space limitations, ease of installation, structural rigidity, and RF tuning ability. The striplines are supported by a quarter-wavelength “stub”, mid span, for support during thermal cycling and plasma disruption events. Multiphysics FEA analyses are performed to optimize the geometric shapes to meet the aforementioned design challenges. A description of the mechanical design, fabrication, installation, and analyses of the HPHA and stripline feeds will be presented

A Broadband Stripline Technique for Characterizing Relative Permittivity and Permeability

We present a stripline design and calibration method allowing the extraction of relative permittivity of single dielectric samples in the 200-MHz–50-GHz range. The simultaneous extraction of relative permittivity and permeability is also illustrated by characterizing a set of samples comprising magnetic inclusions over the same frequency range. The calibration method involves the use of seven measurements of the stripline scattering parameters (S-parameters) with different length shorts inserted. From these measurements, it is possible to determine the reflections at the transition regions of the stripline to correct the measured S-parameters for characterization. By quantifying a range of samples with increasing percentage volume filling of barium titanate in polyurethane for the case of dielectric samples, and carbonyl iron powder for magnetic samples, this paper demonstrates a reliable method for the broadband characterization of composite materials.

Interaction Features of Stepped-Impedance Stripline Resonators in Comb Filters

Mixed coefficients of coupling between the closely spaced stepped-impedance resonators in comb filters of stripline design have been investigated. Transmission zeros at frequencies f zi correspond to mixed coupling coefficients k i . These zeros can be moved with respect to the filter passband central frequency f0 by modifying the shape of resonators. It was proved that the reduction of gap between resonators made it possible to locate frequencies f z and f0 closer to one another. The existing restrictions on the minimal value of gap between resonators limit the degree of proximity between f z and f0. The N-resonator stripline comb filters with mixed coupling can have N−1 transmission zeros. The absence of cross-coupling links in stripline filters simplifies their construction. It has been established that the thickness of central conductors of stripline resonators affects the positive and negative mixed coupling coefficients. The paper presents measurement data of miniature stripline three-resonator comb filter having an enhanced selectivity at the expense of two transmission zeros. The central frequency of filter is f0 = 1850 MHz, the bandwidth BW = 100 MHz. The filter having dimensions 5.8×4.2×2 mm was implemented by connecting two ceramic substrates having relative dielectric permittivity e r = 92 and the metallized patterns deposited on them.

Thin stripline bandpass filters for the centimeter band

This article considers the design of thin stripline (1 mm) bandpass filters in the centimeter band, which contain dielectrics with different relative permittivity er. This includes the choice of the resonators, the dielectric material, the preliminary assessment of resonators’ unloaded quality factors and taking into account the features of the frequency response curve of the filter. It was found, that the passband width of the thin comb filters with λ/4 resonators and array-type filters with λ/2 resonators cannot exceed 6% for any values of er and the length of resonators of at least 2 mm. The array-type filters with resonators of half-wave type and with alternating signs of the coupling factors between resonators were proposed. Under certain additional conditions, the attenuation poles appear in such filters, resulting in improved selectivity. The results of computer modelling of the frequency response curve of thin filters of cm band are presented. They are compared to the frequency response of other filters. The data obtained from computer modelling showed good correspondence with the experimental data.

Slot antenna single layer fed by step impedance strip line for Wi‐Fi and Wi‐Max applications

To design a slot antenna intended to work at four bandwidth frequency groups, which meet the specifications of (DO,1xRTT-3G), (WiMAX-IEEE802.11e), (WiMAX-IEEE802.16m) and (Wi-Fi.802.11b,g, & n) communications. The slot in the proposed antenna taken the form of the character (Q) that was feed by step impedance micro strip line design open mouth ended. The surface current distribution at resonant frequencies and the effect of varying the dimensions of the parameters on impedance bandwidth had been studied carefully in this research to enhance the performance of resonant frequency.

Wideband planar filters with an extended stopband

An approach to the construction of wideband bandpass filters of microstrip and stripline designs, which have an extended stopband and can incorporate lumped capacitors, is proposed. This approach is based on resonators with the enhanced frequency diversity of fundamental and parasitic resonance frequencies and coupling circuits formed according to an assigned rule. The potential of the filters achieved due to the proposed technique is established. In particular, a very wide passband whose ratio of cuttoff frequencies is 5: 1, as well as the stopband greater than an octave at a level of 40 dB, is demostrated to be attainable. When the passband is narrower, the stopband can exceed two octaves. The given approach can be applied to filters operating in a broad frequency range, including to that corresponding to centimeter and meter waves. The experimental data are presented.

Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor.

Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.

Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

재구성 특성을 갖는 다중대역 이동통신 단말기용 안테나의 설계 및 제작

In this paper,a reconfigurable multi-band mobile antenna with switching line for LTE band 13, GSM, K-PCS, WCDMA band. The proposed antenna is planar strip line design and composed of stub shorted to the ground plane and two switching line for proposed band operation. To obtain the optimized parameters, we used the simulator, Using the obtained parameters is fabricated. The numerical and experiment results demonstrated that the proposed antenna satisfied the -6 dB impedance bandwidth requirement while simultaneously covering when the state of sw1 and sw2 on for LTE band 13, the state of sw1 off and sw2 on for GSM, K-PCS, the state of sw1 off and sw2 off for WCDMA. Respectively and characteristics of gain and radiation patterns are determined for a reconfigurable multi-band mobile terminal.

Stripline design for the extraction kicker of Compact Linear Collider damping rings

In the framework of the design study of future linear colliders, the Compact Linear Collider (CLIC) aims for electron-positron collisions with high luminosity at a nominal center-of-mass energy of 3 TeV. To achieve the luminosity requirements, predamping rings (PDRs) and damping rings (DRs) are required: they reduce the beam emittance before the beam is accelerated in the main linac. Several kicker systems are needed to inject and extract the beam from the PDRs and DRs. In order to achieve both low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. In this paper, we present the complete design of the striplines for the DR extraction kicker, since it is the most challenging from the field homogeneity point of view. The excellent field homogeneity required, as well as a good transmission of the high voltage pulse through the electrodes, has been achieved by choosing a novel electrode shape. With this new geometry, it has been possible to benefit from all the advantages that the most common shapes introduce separately. Furthermore, a detailed study of the different operating modes of a stripline kicker allowed the beam coupling impedance to be reduced at low frequencies: this cannot be achieved by tapering the electrodes. The optimum design of the striplines and their components has been based on studies of impedance matching, field homogeneity, power transmission, beam coupling impedance, and manufacturing tolerances. Finally, new ideas for further improvement of the performance of future striplines are reported.

VISAR 'cross-hairs': Simultaneous perpendicular line-imaging VISAR

Often the velocity measured at the rear surface of a dynamic compression target varies spatially, caused for instance by the tilt/curvature of a gas gun flyer, asymmetries in the magnetic field on a pulsed power driven experiment, or meso-scale heterogeneous targets. One way to monitor this in an experiment is to employ multiple point velocimetry techniques, but even with multiplexing this can become expensive in terms of hardware, in particular high speed sensors and scope channels. We report on the initial development of a multi-axis line-imaging VISAR system, which will record the spatial velocity along two orthogonal directions. Cylindrical optics are used to project a set of cross-hairs onto the target, maximising the use of input laser light; we then describe the image relay, interferometer configuration and alignment. This 'quasi' two dimensional system will become one of the principal diagnostics on the MACH (Mega Ampere Compression and Hydrodynamics) facility at Imperial College London, where the multi-axis measurement will help optimise strip-line design to achieve uniform ramp compression of targets.

Design and Implementation of a TEM Stripline for EMC Testing

In this paper, a stripline for radiated field immunity testing of audio/video products is designed, constructed, calibrated, and verified. Since the canonical one is only suitable for testing equipments with height less than 70 cm, there is a need of a new device which is also in compliance with EN 55020 standard for testing new large sets, like 47'' thin-film transistor liquid crystal display (TFT LCD) television sets, in the frequency range of 150 kHz-150 MHz. Increasing the height and width of testing area causes important problems in terms of field uniformity regarding the higher order modes, characteristic impedance, and reflections in addition to the room resonances and field interference sources like corners at the edges of stripline. Comprehensive numerical study is performed to overcome these problems and obtain the optimum design before the construction. Measured data show that the new stripline is in very good agreement with the specifications determined by the standards and therefore it can be used for the electromagnetic compatibility (EMC) testing.