Miniaturized spoof SPPs filter based on multiple resonators or 5G applications

This paper presents a novel and compact band-pass filter based on spoof surface plasmon polaritons (SSPPs) concept for 5G applications. In the first place, an SSPPs unit cell including L-shaped grooves and its equivalent circuit model are introduced. The obtained results from dispersion analysis shows that cut-off frequency of the cell can be considerably decreased thanks to its geometrical configuration. In the second place, a miniaturized SSPP transmission line (TL) consisting of the proposed unit cell with cut-off frequency of 29.5 GHz is designed. Two mode convertors have been employed for efficient connection between coplanar waveguides and SSPP TL. Moreover, a new method based on loading one unit cell of SSPP TL by stub resonators is proposed in order to block a specific frequency band. An equivalent circuit model for the cell with the resonators is proposed to predict rejected frequency range. Thereafter, as an example of our method, a SSPPs filter operating at 26.5–29.5 GHZ is designed by means of connecting stub resonators with different lengths to provide close resonance frequencies. The circuit model, full wave simulation, and measurement results are in a good agreement. The results of proposed groundless SSPP TL and filter structures are promising to make groundless 5G applications possible.

A Comprehensive Review of EMI Filter Network Architectures: Synthesis, Optimization and Comparison

This paper presents a volumetric comparison among three possible optimized three phase EMI filter structures, a three phase PFC converter used in cutting edge applications, such as avionics, space or shipboard power systems. The size minimization of each of the filter structures, described in the paper, was performed utilizing the volumetric optimization methodology proposed in the paper. This paper theoretically demonstrates the design steps for choosing the appropriate filter component values and number of filter stages to achieve the smallest volume of the DM filter stage for any given EMI filter structure. While the validation of the proposed design methodology was done through a MATLAB simulation, an experimental verification was also performed by designing and comparing the optimized EMI filter structures for a 2.3 kW proof-of-concept of a three-phase boost PFC converter for more electric aircraft (MEA) applications to comply with the stringent EMI requirements of the DO-160F standard.

High-resolution imaging of depth filter structures using X-ray computed tomography

A multiple length scale approach to the imaging and measurement of depth filters using X-ray computed tomography is described. Three different filter grades of varying nominal retention ratings were visualized in 3D and compared quantitatively based on porosity, pore size and tortuosity. Positional based analysis within the filters revealed greater voidage and average pore sizes in the upstream quartile before reducing progressively through the filter from the center to the downstream quartile, with these results visually supported by voidage distance maps in each case. Flow simulation to display tortuous paths that flow may take through internal voidage were examined.Digital reconstructions were capable of identifying individual constituents of voidage, cellulose and perlite inside each depth filter grade, with elemental analysis on upstream and downstream surfaces confirming perlite presence. Achieving an appropriate pixel size was of particular importance when optimizing imaging conditions for all grades examined. A 3 µm pixel size was capable of representing internal macropores of each filter structure; however, for the finest grade, an improvement to a 1 µm pixel size was required in order to resolve micropores and small perlite shards. Enhancing the pixel size resulted in average porosity measurements of 70% to 80% for all grades. Graphical abstract

LOW POWER DIGITAL FILTERING USING ADAPTIVE APPROXIMATE PROCESSING: FIR FILTER STRUCTURES

Techniques for reducing power consumption in digital circuits have become increasingly important because of the growing demand for portable multimedia devices. Digital filters, being ubiquitous in such devices, are a prime candidate for low power design. Algorithmic approaches to low power frequency-selective digital filtering which are based on the concepts of adaptive approximate processing have been developed and formalized by introducing the class of approximate filtering algorithms in which the order of a digital filter is dynamically varied to provide time-varying stopband attenuation in proportion to the time-varying signal-to-noise ratio (SNR) of the input signal, while maintaining a fixed SNR at the filter output. Since power consumption in digital filter implementations is proportional to the order of the filter, dynamically varying the filter order is a strategy which may be used to conserve power. In this paper we introduce a class of approximate filter structures using FIR digital filter constituent elements. These filter structures are explored and shown to be an important element in the characterization of approximate filtering algorithms.

A compact dual-band D-CRLH-based antenna with self-isolation functionality

This paper presents a compact dual-band filtering antenna without extra employing of filter structures. The antenna is designed using a planar dual-composite right/left-handed (D-CRLH) transmission line unit cell, where the filtering function is achieved through current cancellation between the D-CRLH resonators. The antenna is designed to function at 3.0 and 5.1 GHz, which can serve different WLAN applications. The antenna is a co-planar waveguide fed with a very compact size of only 30 × 16 mm2. Compared to the conventional patch antenna, the antenna size is only 17% at 3.0 GHz and 31% at 5.1 GHz. Despite the small size, the antenna preserves a good omni-directional radiation pattern at the two resonant frequencies with a measured realized gain of 2 and 2.7 dB, respectively. At the stopband in-between the two resonant bands, the reflection coefficient is almost 0 dB at 4.25 GHz and complete non-radiation is proved with a −11 dB measured realized gain. The different antenna filtering functions are verified by full-wave simulation and measurements.