Explore the vast range of titles available.

A novel and compact microstrip ultra-wideband (UWB) bandpass filter (BPF) based on a triple-mode resonator is designed, fabricated and measured. The proposed resonator is composed of a coupled line with a half-pass characteristic, which is connected directly with each other at one end and is short-circuited to the grounding plane at the other end. A simple structure and design approach to the proposed filter is provided and demonstrated. To implement the design on a microstrip, the directly tapped-transition input/output ports are used to excite the coupled-line multi-mode resonator. The measured results are in good agreement with the electromagnetic simulated results. The proposed filter shows a 3 dB fractional bandwidth of 117.3% at the central frequency (/)) with a return loss of better than 12 dB and an insertion loss of < 0.5 dB within the passband response. [PUBLICATION ABSTRACT]

A broadband hybrid power amplifier using a gallium nitride (GaN) high electron mobility transistor (HEMT) is presented. A discrete GaN HEMT bare die with 1.25 mm of gate width is used, and a compact size of 8.3 × 12.7 mm is achieved by using a feedback technique based on lumped elements. The power amplifier operates from 100 to 1000 MHz, and shows more than 12.8 dB gain and higher than 30.7 dBm output power in the overall bandwidth. Power added efficiency of 61.3% was acquired at the mid-band frequency and more than 54.5% throughout the bandwidth. [PUBLICATION ABSTRACT]

This paper presents an ultra-low-power second-order Chebyshev active-RC complex filter for a low-IF ultra-low-power receiver. By utilising a pole-cancellation push-pull buffer with feedforward phase compensation technology, the operational amplifier (opamp) realises superior stability while maintaining high gain bandwidth and ultra-low power consumption. A second-order complex filter with four proposed opamps and an adaptive bias fabricated in standard 180 nm CMOS process consumes only 460 mu W at 1.8 V power supply. The measured centre frequency is 3 MHz and bandwidth is 2 MHz, while it achieves 32 dB image rejection ratio at the centre frequency.

The bandwidth of tapered slot antennas (TSAs) is usually limited by the bandwidth of the feed used and typically does not exceed a few octaves, even though the TSA itself possibly can operate at a wider frequency range. Presented, and discussed, is a planar TSA feeding scheme that makes use of an external 1808 hybrid. Design guidelines and analytical formulas are presented for this hybrid connection scheme.

The existence of missing geomagnetic reversals has been proposed, with potential for new magnetostratigraphic age controls. We estimate geomagnetic reversal frequency from 0 to 155 Ma using adaptive‐bandwidth kernel density estimation (AKDE) to evaluate data sparseness and to assess how reversal frequency changes when recently identified geomagnetic reversals are incorporated into the geomagnetic polarity time scale (GPTS) data set. AKDE is a two‐stage procedure that uses an initial density estimator based on an initial (pilot) bandwidth. We found that the pilot bandwidth determined using cross‐validation is stable with respect to data set length. The AKDE results obtained based on the cross‐validated pilot bandwidth reveal four troughs after the Cretaceous Normal Superchron, spaced 13.5–15.0 Myr apart and corresponding to relatively long chrons (>0.8 Myr). One trough near 32 Ma becomes less distinct after the four recently identified reversals are added to the data set. This sensitivity suggests that troughs in the frequency curve may indicate missing geomagnetic reversals.

A compact triple-band coplanar waveguide (CPW)-fed antenna for WLAN/WiMAX applications is proposed. The radiation patch is fed by capacitive coupling of the top transmission line. By only using one metallic strip etched on the bottom of the substrate, tri-band resonances of the antenna are generated. The proposed antenna has a compact size of 30 × 27 mm2, which can provide stable omnidirectional radiation patterns in three bands. The measured − 10 dB impedance bandwidths are 150 MHz (2.39–2.54 GHz), 360 MHz (3.37–3.73 GHz) and 1170 MHz (5.02–6.19 GHz), which is suitable for WLAN/WiMAX applications.

Following a brief review of current progress in the field of nonlinear targeted energy transfer (TET), we discuss some general ideas and methods in this field and describe certain possible future venues for further developments; these go beyond the current paradigm of implementing TET by means of nonlinear energy sinks. Four such emerging research fields are discussed, namely (i) the new and promising concept of intermodal targeted energy transfer, (ii) the implementation of TET in nonlinear acoustic metamaterials, (iii) the break of classical reciprocity in elastodynamics in the context of TET, and (iv) the role of TET on the bandwidth of general classes of nonlinear resonators. Our aim is to describe the main ideas, summarize recent developments, outline possible directions for future work, and possibly trigger further research in the discussed topics and also in other possible TET-related topics not discussed herein.

A symmetrical Fe2O3/BaCO3 hexagonal cone structure having a height of 10 um and an edge length of -4um is reported, obtained using a common solvothermal process and a mirror growth process. Focused ion beam and high-resolution transmission electron microscopy techniques revealed that α-Fe2O3 was the single crystal feature present. Ba ions contributed to the formation of symmetrical structures exhibited in the final composites. Subsequently, porous magnetic symmetric hexagonal cone structures were used to study the observed intense electromagnetic wave interference. Electromagnetic absorption performance studies at 2-18 GHz indicated stronger attenuation electromagnetic wave ability as compared to other shapes such as spindles, spheres, cubes, and rods. The maximum absorption frequency bandwidth was at 7.2 GHz with a coating thickness d = 1.5 mm. Special structures and the absence of BaCO3 likely played a vital role in the excellent electromagnetic absorption properties described in this research.

Federated learning aims to collaboratively train a machine learning model with possibly geo-distributed workers, which is inherently communication constrained. To achieve communication efficiency, the conventional federated learning algorithms allow the worker to decrease the communication frequency by training the model locally for multiple times. Conventional federated learning architecture, inherited from the parameter server design, relies on highly centralised topologies and large nodes-to-server bandwidths, and convergence property relies on the stochastic gradient descent training in local, which usually causes the large end-to-end training latency in real-world federated learning scenarios. Thus, in this study, the authors propose the adaptive partial gradient aggregation method, a gradient partial level decentralised federated learning, to tackle this problem. In FedPGA, they propose a partial gradient exchange mechanism that makes full use of node-to-node bandwidth for speeding up the communication time. Besides, an adaptive model updating method further reduces the convergence rate by adaptive increasing the step size of the stable direction of gradient descent. The experimental results on various datasets demonstrate that the training time is reduced up to $14 \\times $14× compared to baselines without accuracy degrade.