Narrow-band Impedance Research Articles

Generalized threshold of longitudinal multibunch instability in synchrotrons

Beam stability is a crucial requirement for all particle accelerators. Coupled-bunch instability (CBI) is driven by beam interaction with narrowband impedance of the resonant accelerator components. Loss of Landau damping (LLD) for a single bunch is mainly determined by broadband impedance and can lead to undamped bunch oscillations. For the first time, we solve numerically the longitudinal stability problem in a self-consistent way for a general case of two impedance types and propose a simple analytical criterion describing how the obtained LLD and CBI thresholds are combined. We demonstrate that LLD can modify the CBI mechanism and reduce the instability threshold even below the LLD threshold. These findings allow the existing beam observations in CERN Super Proton Synchrotron and Large Hadron Collider to be explained and should be considered in design of the future accelerators. Published by the American Physical Society 2024

Design and Analysis of Dual Narrow Band MIMO (DNB-MIMO) Antenna for IoT Applications

A compact DNB-MIMO antenna design and analysis for IoT application was proposed. The antennaradiator consists of 2 L-shaaped quarter-wavelengths and inverted 7-shaped radiators with a microstrip feed line, and partial ground plane with a size of 32 × 15 mm2. This antenna achieves a higher quality factor (Q > 10) and narrow band impedance matching at the central frequencies of 1.8 GHz and 2.4 GHz bands with approximately 8.2% and 6.2% bandwidth respectively. The suitability of the designed antenna for IoT applications is verified through the hosting device model. The proposed 4-port MIMO antenna has an overall size of 60 × 60 ×1.6 mm3, and it is printed on an FR4 substrate. The diversity add comma such as ECC, DG, TARC, MEG, and CCL, are calculated and there values are < 0.19, 9.85 dB, < -25 dB, < -6 dB, < 0.19 bits/Hz/s, respectively, within the limits. The proposed antenna is integrated with the Zigbee module (lowercase) to analyze the performance for IoT applications at 2.4 GHz

Double-Conversion, Noise-Cancelling Receivers Using Modulated LNTAs and Double-Layer Passive Mixers for Concurrent Signal Reception With Tuned RF Interface

A double-conversion, noise-cancelling receiver architecture is presented that consists of a double-layer mixer-first branch and two quadrature-modulated LNTA branches. The two layers of passive mixing in the mixer-first branch up-convert the low-pass, baseband impedance and create concurrent, narrowband impedance matching at (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LO</sub> ±F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IF</sub> ), as well as concurrently receive signals around these two RF carriers while rejecting spurious responses without using any IF filters. To improve the noise performance, quadrature-modulated LNTA branches are incorporated to allow frequency-translational, noise cancellation for better receiver sensitivity. Double conversion is achieved in the LNTA branches by periodically varying the LNTA transconductance and current-mode, passive mixing. A generalized, linear time-varying (LTV) analysis of the receiver is presented and verified with behavioral-model simulation results.

Study on beam-induced heating in injection section of Hefei Light Source

Ceramic chambers distributed with metal striplines on the inner surface are installed in the injection section at Hefei Light Source (HLS). Heating on the ceramics chambers has been observed during machine operation. An air compressor is used to cool these chambers due to concerns of overheating during top-up operation mode. To understand the sources of the heating, a series of experiments are performed with various beam currents and bunch filling patterns. The study shows that the heating is mainly caused by the narrow-band impedances of the ceramic chambers and their adjacent vacuum components.

Narrowband Impedance Transformer With Extremely High Transformation Ratio of 200

This letter presents a hybrid narrowband radio frequency (RF) impedance transformer using an aluminum nitride (AlN) microelectromechanical system (MEMS) resonator and lumped elements. The hybrid transformer consists of an AlN Lamb wave resonator, a parallel inductor, and a set of three lumped-element networks on a printed circuit board (PCB). The AlN resonator and the parallel inductor form the narrowband response while the lumped element networks fulfill the high impedance transformation. The transformer has been theoretically predicted and experimentally shown to achieve a narrow fractional bandwidth (FBW) of 2.2% and an extremely high impedance transformation ratio (ITR) of 200.

Modified Q-Based Real Frequency Design of Narrowband Impedance Equalizer with Complex Terminations

In this paper, real frequency design equations of narrowband impedance matching network with complex terminations are derived; which are used to design L, Pi and T type of networks. In the approach, there is no need to have termination models with component values, it is enough to have measurement values of termination impedances. A few examples are solved to exhibit the merits and application of the derived equations.

Excellent Microwave Absorption Properties Derived from the Synthesis of Hollow Fe₃o₄@Reduced Graphite Oxide (RGO) Nanocomposites.

Magnetic nanoparticles, such as Fe3O4 and Co3O4, play a vital role in the research on advanced microwave absorbing materials, even if problems such as high density and narrow band impedance matching are still unsolved. Herein, the study of lightweight hollow Fe3O4@reduced graphite oxide (RGO) nanocomposites synthesized via the solvothermal method is presented. The microstructure and crystal morphology of the materials were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Single crystalline hollow Fe3O4 spheres were grown onto RGO flakes, leading to the formation of heterojunction, which further influenced the microwave absorption properties. The latter were evaluated by standard microwave characterization in the frequency range of 2–18 GHz. It was found that, for a specific Fe3O4@0.125 g RGO composite, the minimum reflection loss can reach −41.89 dB at 6.7 GHz, while the reflection loss was less than −10 dB from 3.4 GHz to 13.6 GHz for a nanocomposite sample thickness in the range of 1–4 mm. The combination of these two materials thus proved to give remarkable microwave absorption properties, owing to enhanced magnetic losses and favorable impedance matching conditions.

GPS Signal Anti-Jamming Assisted with Probability Statistics based on Frequency-Space Domain

Global Positioning system signal is frail and powerless. Scoring channel fell with space channel can enhance counter sticking capacity of GPS beneficiary can utilize recurrence area. It is hard to identify the narrowband sticking goads effectively by quick Fourier change when narrowband sticking falls in wideband. Likelihood insights calculation is proposed to help distinguish narrowband obstruction area in recurrence range. It's valuable to utilize likelihood insights recurrence area separating calculation to check irregular flag. Since narrowband obstruction might be submerged in broadband impedance a timeframe so it is elusive narrowband impedance tops in a few casings after FFT changing. It is demonstrated, both spatial and transient marks of signs impinging on multi-sensor recipient accept comparative parts in collector execution. Spatial and transient marks’ separate connection coefficients show up as square multiplicative items in SINR articulation. Numerical outcomes demonstrate proposed calculation which performs well.

Voltage Mode Doherty Power Amplifier

This paper presents a new wideband Doherty amplifier technique that can achieve high efficiency while maintaining excellent linearity. By modifying a “forgotten” topology originally proposed by Doherty, a new Doherty amplifier architecture is realized with two voltage mode power amplifiers (PAs) and transformers, thus eliminating a narrowband impedance inverter. The voltage mode PA is implemented using switched capacitor PA techniques. The PA is fabricated in 65-nm low-leakage CMOS and achieves 24-dBm saturated power (at the standard supply voltage) with PAE of 45% at peak power and 34% at 5.6-dB back-off over 750 to 1050 MHz 1 dB bandwidth. With memory-less linearization, the PA can transmit 40 MHz 256-QAM 9 dB peak-to-average power ratio 802.11ac modulation centered at 900 MHz meeting the spectral mask with measured EVM of -34.8 dB and 22% PAE without backing off or equalization.

Design and Analysis of Rectangular Microstrip Patch Antenna for ZigBee Applications

A rectangular micro strip patch antenna is presented in this paper for 915 MHz band applications. These applications include Zig Bee and Bluetooth. The potential of Zig Bee technology is enormous due to its tremendous advantages such as the capability to provide extremely fast data rates at short transmission distances while requiring very low power dissipation. Recently, printed antennas have played a major rule in development of antennas with different frequencies. The construction of proposed antenna is done on FR-4 epoxy substrate with thickness of 1.6 mm. The proposed antenna operates from 902MHz to 928MHz with good omni directional radiation patterns, its narrow band impedance bandwidth protect it from interference problem from other applications in ISM band. Proposed antenna has compact size of (60x30)mm2. It has advantages in simple design, narrow bandwidth, and compact in size and easy in fabrication. The measured result is in good agreement with simulated one.

Low-noise amplifier with narrow-band and wide-band input impedance matching design

A low-noise amplifier (LNA) with cascode structure and shunt-peaking load is presented in this article. Both Narrow-band input impedance and wide-band input impedance LNAs were implemented in 0.18 μm CMOS process. Maximum power gain of the narrow-band input impedance LNA is 19.3 dB; maximum power gain of the wide-band input impedance LNA is 15.3 dB. Minimum noise figure of the narrow-band input impedance LNA is 3.1 dB; minimum noise figure of the wide-band input impedance LNA is 3.0 dB. Power consumptions including buffers are 24.5 and 25.6 mW, respectively.

Narrow-band impedance of a round metallic pipe with a low conductive thin layer

The new traveling wave structure with a single synchronous mode resonantly excited by the relativistic charge is presented. The structure is composed of a metallic tube with an internally coated low conductive thin layer. It is shown that the impedance of the internally coated metallic tube has a narrow-band single resonance at a high frequency. The analytical presentation of the narrow-band impedance, the wake function, and the frequency of the synchronous mode are obtained. The analytical solutions are compared with exact numerical simulations using the field matching technique.

A fully integrated rf front end for DVB‐SH

AbstractThis article describes a RF front end for DVB‐SH (2.17–2.2 GHz) implemented in UMC CMOS 90 nm process. This receiver includes a low noise amplifier (LNA), a single‐to‐differential converter, and a mixer. The LNA is based on cascode topology combined with a narrow band impedance matching and LC tank load. The single‐to‐differential converter generates a pair of differential output signals from a single input, which have balanced amplitude and phase. This converter is followed by a Gilbert cell based quadrature mixer. The measurements show a conversion gain of 15.7–15.5 dB, an input return loss (S11) of −12 dB, and an output compression point of 1.92 dBm. This receiver has a simulated noise figure of 2.2 dB. This combination draws 22 mW from a 1.2‐V supply. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1944–1949, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26974

A 1.6/1.8/2.1/2.4-GHz Multiband CMOS Low Noise Amplifier

This paper describes an inductively source degenerated multiband low noise amplifier (LNA) designed in a standard CMOS 0.18 μm TSMC process. The multiband LNA can be tuned to 1.6-GHz, 1.8 GHz, 2.1 GHz and 2.4 GHz with the help of switches. The narrowband gain and impedance matching are obtained at the required frequency bands by appropriately switching the transconductance, input and output capacitances. The switches are realized using metal-oxide-semiconductor (MOS) transistors. The designed LNA exhibits a gain of 16.2dB, 16dB, 15.5dB and 15.5dB and a noise figure of 3.3dB, 3.5dB and 3.2dB at 1.6, 1.8, 2.1 and 2.4 GHz respectively. The LNA design is carried out using Mentor Graphics Eldo software.

Accurate measurement method for characterisation of RF impedance tuners

The design and measurement of a compact narrowband impedance matching network is presented. The device has been realised in hybrid technology: coplanar waveguide transmission lines and surface-mounted components. The experimental results were carried out through two different measurement methods, a traditional approach and a new faster, simpler one giving the same results. They show that complex impedances with magnitudes varying from 6.3 to 1120 Ω can be matched with a 50% bandwidth around the centre frequency.

Review of narrowband impedance-matching limitations

Many antennas can be characterized by their radiation Q (the ratio of reactance to radiation resistance). A classic problem is determining the maximum possible bandwidth, constrained by the maximum permissible reflection magnitude, and the number of tuned circuits in the impedance-matching circuit. This paper presents a review on theoretical limitations of narrowband impedance matching.

Relaxation oscillations of the synchrotron motion caused by narrow-band impedances.

Although the linearized theory of small amplitude synchrotron oscillations and the instability thresholds derived from it have long been understood, there is no satisfactory description of the large amplitude highly nonlinear synchrotron motion of a bunched beam. With an appropriate tuning of the RF cavity impedance, large amplitude, low frequency, self-sustained relaxation oscillations of this synchrotron motion are generated. This paper presents detailed experimental data on such behavior, tracking code results that reproduce the important characteristics, and a simple analytical model that explains the key features of the relaxation oscillation: growth of the instability, saturation of the oscillation, breakup of the bunch, and subsequent damping of the system back to the beginning of the next cycle of the relaxation oscillation.

Beam break-up with tune chirp for an arbitrary wakefield

The asymptotic form of the beam break-up instability is computed up to quadrature for an arbitrary wakefield, in the presence of a linear variation in betatron tune from head to tail along the beam. For illustration, the result is applied to a broadband impedance (resistive wall) and a narrow band impedance (single resonator) and benchmarked against simulation, for parameters of interest in induction linacs.

Space-charge-dominated bunched beams in the frequency domain.

The effect of space charge on high-phase-space-density bunched beams in an ion storage ring with electron cooling is investigated in the frequency domain for bunches in the vicinity of the local microwave instability threshold. Space charge causes a splitting of synchrotron satellites into incoherent and coherent lines. Results of measurements of the splitting and shift are compared with analytical formulas as well as with simulation of the noise spectra by multiparticle computer simulation. Coherent frequencies of the quadrupole and sextupole modes of Gaussian bunches are found to deviate slightly from the analytical mode frequencies. Consequences for the interaction with narrow-band impedances and on the possible accuracy of \ensuremath{\Delta}p/p momentum-spread measurements for high-phase-space-density bunches are briefly discussed. \textcopyright{} 1996 The American Physical Society.

Longitudinal bunched-beam instabilites going nonlinear: Emittance growth, beam splitting, and turbulence.

Numerical results of the nonlinear evolution of longitudinal instabilities of bunched beams are presented. Only a pure-dipole instability is considered which appears for the short-bunch, long-wavelength-of-impedance situation, when the wake-field force is a linear function of the coordinate. An argument is made for a rescaling of multibunch dynamics to a single-bunch case for the case of a narrow-band impedance exciting a single coupled-bunch mode. Saturation effects due to the decoherence caused by tune spread are categorized according to the magnitude and type of impedances. The phenomenon of a nonsaturating instability (beam splitting) is described. A slow decay of instabilities after saturation with randomlike bunch-centroid oscillations (``beam turbulence'') is observed and discussed.