Wide Rejection Research Articles

Compact high attenuation wide rejection bandwidth 5-pole Butterworth LPF using transmission zeros in GaAs process

In this work, a systematic design method for a compact 5-pole Butterworth transverse resonance low pass filter (TR-LPF), in 0.15 μm Gallium Arsenide process, with wide rejection bandwidth (RBW), is presented. The circuit model of TR-LPF and closed-form expressions are provided to appreciate the design process. The fabricated TR-LPF has a cut-off frequency of 10.5 GHz, an insertion loss of 0.4 dB, and the return loss is better than 20 dB. The 20 dB, 30 dB, and 40 dB deep rejection bandwidths (RBWs), across 50 GHz, 45.5 GHz, and 17 GHz respectively, are obtained. The novel use of stubs and spur resonators, within stubs; provides the deep and wide RBW. The compactness of the TR-LPF is realized by the ‘C’-and ‘Z’-shaped folding of stubs. The dimension of the filter is approximately 0.11λg×0.079λg.

Design of Miniaturized 90-Degree Hybrid Coupler with Wide Rejection Band Using Neural Network.

In this paper, a 3 dB 90-degree hybrid coupler with size reduction and harmonics rejection was designed. In the proposed coupler structure, four simple low-pass filters (LPFs) were applied. An artificial neural network (ANN) was used to determine the dimensions of the applied LPFs based on EM simulation data. The applied ANN model could also provide the desired LPF parameters, including the cut-off frequency (fc), bandwidth (BW), and insertion loss (IL). Designing an applied LPF involves complex mathematical calculations and simulations to optimize parameters. However, by utilizing neural networks, the design process can be significantly streamlined and automated. Neural networks have the ability to learn complex patterns and relationships within data, making them well suited for optimizing the performance of applied components. The proposed 90-degree hybrid coupler works correctly at 1800 MHz and has a small size of 16.6 mm × 15.15 mm, which provides a 73% size reduction compared to a normal 1800 MHz coupler. The designed coupler not only decreases the circuit size but also provides a wide rejection band from 4.8 GHz to 11.2 GHz, which suppresses the second to sixth harmonics. The insertion loss parameter of this 90-degree hybrid coupler is less than 0.1 dB at the working frequency, which shows the superior performance of the proposed coupler.

Design of single‐layer bandstop fractal frequency selective surface based on WLAN applications

AbstractIn this letter, we present a new frequency selective surface (FSS) for shielding 2.4–2.5 and 4.98–5.825 GHz wireless local area network (WLAN) bands. This FSS structure is based on the traditional Sierpinski octagon and we improve it. Compared with the traditional structure, the improved one has a smaller element size and better angular stability. The design is realized on float glass with a relative permittivity () of 8, and the unit cell size is 0.1152λ0 × 0.1152λ0 (λ0 is the free space wavelength at the first resonant frequency). Wide rejection bandwidths (−10 dB) of 910 and 1630 MHz are obtained at 2.4–2.5 and 4.98–5.825 GHz, respectively. The surface current distribution and the equivalent circuit model are illustrated to explain the resonance behavior of the proposed FSS. Furthermore, this FSS exhibits stable frequency response to incident angles of 0°–80° under transverse electric and transverse magnetic polarizations. Finally, this FSS structure was fabricated and measured. The measured results demonstrate that this FSS structure has good performance in WLAN applications.

High-Roll-Off-Rate Ultrathin Polarization-Rotating Frequency Selective Surface

This letter introduces a transmission FSS with excellent roll-off feature, ultra-thin thickness, low insertion loss and wide rejection bands. Three novel basic component structures are developed based on the polarization rotator (PR) structure leading to multi-transmission zeros and poles which can be independently controlled. Theoretical analyses and simulations are carried out, and a prototype is fabricated and measured. The proposed FSS exhibits double sharp roll-off sidebands, ultra-thin thickness and low insertion loss, as well as two wide stopbands. In addition, the proposed FSS shows stable responses with oblique incidence up to 45 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> . As a result, the tight agreement between measurement and simulation validates the design principle.

Euthanasia in Africa: A scoping review of empirical evidence.

The core ethical perplexity is that physician-assisted suicide and euthanasia (PAS/E) contradicts the core value of medical practice which is about the duty of care to preserve life. While most arguments for and against euthanasia emerge from other continents, no African country legalizes or decriminalizes PAS/E. The essence of this scoping review is to collate evidence and scientific voices on euthanasia in Africa by synthesizing empirical articles on the subject in Africa. In this scoping review, a systematic search of five electronic research databases-PubMed, SCOPUS, CINHAL Complete, Allied and Complementary Medicine (AMED), and APA PsycInfo-was conducted to identify relevant articles conducted in Africa on euthanasia. After deduplication with the Rayyan software, the retrieved literature were screened for eligibility, and only eligible articles were included in the review. Relevant data from these articles were extracted and analyzed using narrative synthesis. Only 14 articles reporting empirical studies, conducted in Africa, and published in English, were included in the review after a rigorous screening process. The review shows a wide rejection of euthanasia, but there is not much resistance to passive euthanasia, that is, withholding/withdrawing life-saving medical care from a terminally ill patient, mostly due to advanced age of the patient and the incurability of the illness. Many factors, such as religion, profession, and age help in shaping the way an individual view and understand PAS/E. Professionals take the patient's clinical condition and sociocultural context into consideration when making decisions about end-of-life care. The sociocultural context did not favor PAS/E. Euthanasia will continue to be a subject of controversy and debate in Africa and elsewhere. The majority of Africans hold the duty of care and preservation of life as the hallmark of medical practice, which informs the wide rejection of PAS/E.

Design of high‐efficiency , multi‐octave hybrid continuous mode power amplifier with novel low‐pass filtering matching network

This paper presents a design method for a multi-octave, high-efficiency power amplifier (PA) with a novel low-pass filtering matching network. Both extended continuous Class-F and continuous Class-F−1 are engaged to expand the design space for the ultra-broad operating band. A wideband vertex coupled radial stubs (VCRS) low-pass filter alongside a transmission line network (TLN) is proposed as an output impedance matching network of the PA. The wide rejection band and sharp transition band of this filter make it suitable for harmonic tuning PAs. To verify the feasibility of the proposed structure, the PA is fabricated and its performance is measured. The fractional bandwidth of 155% across 150 to 1200 MHz with a drain efficiency of 61%–73% and output power of 38.9–39.5 dBm is achieved.

Research on Space Rapid Response Launch System based on Data Link

Abstract Space rapid response launch system based on data link is relying on high orbit communication satellites and low orbit comprehensive constellation, to construct the data link tactical time-sensitive network space-based plane, with features of full coverage, wide area interconnection, machine interconnection, flat networking and mobile disturbance rejection, to provide the wide-area multi-field, ocean-sea container, multi-batch rapid response launch capability. This paper has carried out the research on application requirements in combination of the data link and the space rapid response launch, the basic structure of space rapid response launch system based on data link, and the adaptive design method of the rocket and launch unit, so as to promote the generation of multi-domain self-organizing collaborative launch capability.

Miniaturized and Selective Half-Mode Substrate Integrated Waveguide Bandpass Filter Using Hilbert Fractal for Sub-6 GHz 5G Applications

The present paper proposes a novel miniaturized and selective half-mode substrate integrated waveguide (HMSIW) bandpass filter (BPF) using Hilbert fractal geometry. A non-uniform horizontal periodical DGS (HPDGS) is introduced in the ground plane to miniaturize it further and obtain wide and steep outband rejection to enhance the filter's performance. A three-pole bandpass filter (BPF) with a center frequency of 3.5 GHz is simulated, analyzed and designed on a low-cost substrate FR-4 (εr = 4.4). The filter becomes small, shows the low insertion loss of 1.1 dB and return losses of more than 16 dB, and is appropriate for operation from 3.38 to 4.20 GHz spectrum considered for the lower band fifth-generation (5G).

Development of Compactness of Reconfigurable LPF/BSF Using a Simple Technique for Radar Applications

In this paper a new compact reconfigurable low pass/band stop filter using a miniature omega resonator placed in a small DGS in the ground. The reconfiguration in frequency response can be achieved with the same topology and the same dimensions by changing just the position of channel slot which connect the omega resonator to the metallic ground without any other requirements. Several advantages obtained with this structure based on the use of one omega resonator cell such as simplicity of fabrication, very low insertion loss in the pass bands, a high rejection in the stop band with a sharp transition. This filter is suited for many areas of modern communication applications and microwave technology since it shows a simple frequency reconfiguration with a several benefits such a good wide rejection of out of bands signals, high selectivity, compactness and small losses and seize, with total area of 9.08×10mm2 .

Contra-directional pump reject filters integrated with a micro-ring resonator photon-pair source in silicon.

High coincidence-to-accidental ratio (CAR) is crucial for photon-pair sources (PPSs) integrated with pump reject filters (PRFs) in silicon, but CAR values currently reported for integrated PPS/PRF chips still fall short of those achieved using stand-alone sources with external PRFs. Here we report measured and modelled CAR values for a micro-ring resonator PPS integrated with a PRF consisting of a three-stage, cascaded (via their through ports), contra-directional coupler (CDC) that compare favorably even with some stand-alone sources. CDC-based PRFs provide the benefits of compact area and wide reject bands without a need for tuning, in comparison to prior-art implementations.

Miniaturized microstrip suppressing lowpass cell for hybrid applications

In this paper, a very small microstrip low-pass filter (LPF) has presented for utilization in microwave systems. This device is composed of mirrored stepped impedances with two boxes at each side. A transfer function has been extracted from the relevant LC circuit, which expresses the function of this design. The operating frequency of the LPF is located at 3.5 GHz. The proposed LPF blocks a wide rejection with a rejection level of −20 dB or stronger. The return loss of 33 dB is another competence of the LPF. The overall size of the fabricated prototype is 9.5 mm × 5.8 mm (56 mm2). These dimensions maybe give the most compact lowpass filter operating in such frequency among the published work until now. The measurement results mimic the simulations.

Quad-Port UWB MIMO antenna based on LPF with vast rejection band

This manuscript introduces orthogonally polarized quad-element multi-input multi-output (MIMO) antenna with improved isolation. The proposed design of a miniaturized volume of 43 × 43 × 1.5 mm3 covers vast impedance bandwidth more than 17.85 GHz commences at 2.15 GHz to more than 20 GHz, corresponding to reflection coefficient below – 10 dB. A quad-port low-pass filter (LPF) with a very wide rejection band and low cutoff frequency is suggested as a decoupling structure to boost the isolation to more than 20 dB across most of the bandwidth. Equivalent circuit model is scrutinized to investigate the enactment of the decoupling-structure. The MIMO antenna performing satisfies UWB requirements of relatively omnidirectional radiation patterns and stable radiation characteristics with an average gain 5 dBi. Envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), and total active reflection coefficient (TARC) are analyzed to show the applicability of the proposed antenna to the short-range communications. Both simulated and fabricated results demonstrate good agreement.

Realizing UWB Antenna Array with Dual and Wide Rejection Bands Using Metamaterial and Electromagnetic Bandgaps Techniques.

This research article describes a technique for realizing wideband dual notched functionality in an ultra-wideband (UWB) antenna array based on metamaterial and electromagnetic bandgap (EBG) techniques. For comparison purposes, a reference antenna array was initially designed comprising hexagonal patches that are interconnected to each other. The array was fabricated on standard FR-4 substrate with thickness of 0.8 mm. The reference antenna exhibited an average gain of 1.5 dBi across 5.25–10.1 GHz. To improve the array’s impedance bandwidth for application in UWB systems metamaterial (MTM) characteristics were applied it. This involved embedding hexagonal slots in patch and shorting the patch to the ground-plane with metallic via. This essentially transformed the antenna to a composite right/left-handed structure that behaved like series left-handed capacitance and shunt left-handed inductance. The proposed MTM antenna array now operated over a much wider frequency range (2–12 GHz) with average gain of 5 dBi. Notched band functionality was incorporated in the proposed array to eliminate unwanted interference signals from other wireless communications systems that coexist inside the UWB spectrum. This was achieved by introducing electromagnetic bandgap in the array by etching circular slots on the ground-plane that are aligned underneath each patch and interconnecting microstrip-line in the array. The proposed techniques had no effect on the dimensions of the antenna array (20 mm × 20 mm × 0.87 mm). The results presented confirm dual-band rejection at the wireless local area network (WLAN) band (5.15–5.825 GHz) and X-band satellite downlink communication band (7.10–7.76 GHz). Compared to other dual notched band designs previously published the footprint of the proposed technique is smaller and its rejection notches completely cover the bandwidth of interfering signals.

A Dual-Polarized Bandpass Frequency Selective Surface With Stable Response

In this letter, a dual-polarized 3-D frequency selective surface (3-D FSS) based on square metallic waveguides (SMWs) is proposed, which produces a flat passband with two transmission zeros in a relatively wide rejection. Because all resonances occur along propagation direction without complex resonators, a small unit cell size and simple geometry is achieved, resulting in good angular stability and easy implementation. By an equivalent circuit model, its operating principle is explained. At last, the measured results of an implemented FSS show that a stable response under the incident angles up to 60° for dual polarizations is realized.

Anti-Muslim hate on the eastern shores of the Mediterranean: Lebanon, the Hijab, and modernity/coloniality

ABSTRACT Informed by the theorization of the modernity/(de)coloniality studies collective, this paper thinks alongside hijabi women in Lebanon – a small Arab Mediterranean country – and their lived experiences in “mainstream Lebanese society”. Drawing on six-months of qualitative fieldwork through in-depth interviews and focus groups with photo-elicitation, the paper documents and analyses lived experiences of discrimination, exclusion and erasure. Identifying dehumanization, civility and progress, and a present potent wider rejection of Islam in Lebanon, it argues for a framing of participant’s shared experiences as anti-Muslim racism under modernity/coloniality and highlights the need to de-exceptionalize the region and the analytical tools mobilized to understand it.

Circular Split Ring Resonator (C-SRR) Array Integrated Frequency-Notched Horn-Filtenna With Wide and Strong Rejection Band

Linear-array of circular split ring resonators (C-SRR) integrated wideband notched filtering horn antenna with very strong rejection-band is proposed in this article. The linear C-SRR array, consisting of 3-sub arrays each having 4 identical C-SRR-elements, is printed on a dielectric substrate and is integrated into the throat or waveguide-section of the standard X-band horn (Narada 641). Staggered arrangement of the multiple C-SRRs based in-line filter contributes to the wideband notch filtering response with measured rejection band (S11 < 3-dB) of 315 MHz in proposed horn-filtenna. The realized horn-filtenna yields co- and cross- polar peak gain suppression of 35.42 dB and 24.6 dB at and around the centre of notch-band (9.8 GHz) while at the pass band of the C-SRR filter, the proposed antenna inherits the impedance and radiation characteristics of the standalone horn antenna. The proposed technique is simple, easy to integrate and can be used to eliminate adjacent band noise/interference for faithful reception of data without using any additional filter section.

Coplanar waveguide low pass filter based on square complementary split ring resonator with wide rejection

In this paper, we present a novel coplanar waveguide low pass filter (LPF) structure based on the use of square complementary split ring resonators (CSRRs) in order to enhance the performances of a low pass filter. Especially, to enlarge the bandwidth of the LPF, the insertion losses and to increase the rejection of the LPF. The CSRRs are optimised and inserted periodically along the center conductor of the CPW line with a CPW ground integrating stubs permitting to enlarge the bandwidth. The simulation results of this filter show a -3 dB cut-off frequency equal to fc = 5.28 GHz. The designed filter has a good rejection in the stop band which below -20 dB and presents a good insertion loss in the bandwidth. The proposed filter has been fabricated and tested which give a good agreement between simulation and measurement results, the whole dimensions of the validated filter are 35.48x21.16 mm2. The originality of this work is the wide rejection band and the miniature dimensions. © 2020, Universitas Ahmad Dahlan.

Ultraminiaturised Polarisation Selective Surface (PSS) for dual‐band Wi‐Fi and WLAN shielding applications

This study reports on a highly miniaturised polarisation selective surface (PSS) for dual-band Wi-Fi and WLAN applications. The proposed unit cell consists of two independently tuneable square loops. The outer loop is split with a gap of 0.2 mm to introduce polarisation selectivity and miniaturisation for lower-frequency band of 2.5 GHz. The inner square loop is inductively loaded with arms to suppress 5.45 GHz frequency band. These configurations have resulted in a unit element size of at 2.5 GHz, which is not presented before to the best of the authors' knowledge. A wide rejection bandwidth () of more than 600 and 1180 MHz is obtained around 2.5 and 5.45 GHz, respectively. Furthermore, the proposed PSS exhibits an excellent polarisation selective characteristic by generating two stopbands at 2.5 and 5.45 GHz when illuminated by horizontal (TM) incident waves, whereas vertically (TE) polarised incident waves result in the generation of passbands for these two frequencies. Numerical validation through equivalent circuit modelling of the proposed PSS has also been carried out. A finite prototype containing elements is fabricated and tested. The measured results demonstrated that the PSS has excellent potential for applications that employ polarisation separators and wave generators.

A 5.6 μ A Wide Bandwidth, High Power Supply Rejection Linear Low-Dropout Regulator With 68 dB of PSR Up To 2 MHz

High power supply rejection (PSR) with a wide rejection frequency band is becoming a critical requirement in linear low-dropout regulators (LDOs) used in complex systems-on-chip (SOCs). Typical LDOs achieve higher PSR within their loop-bandwidth; however, their supply rejection performance degrades with reduced loop-gain outside their loop-bandwidth. Typical LDOs with external filtering capacitors may also have spectral peaking in their PSR response, causing excess system-level supply noise. This work presents an LDO design approach, which achieves a PSR of higher than 68 dB up to 2 MHz frequency and over a wide range of loads up to 250 mA. The wide PSR bandwidth is achieved using a current-mode feedforward ripple canceller (CFFRC) amplifier which provides up to 25 dB of PSR improvement. The feedforward path gain is inherently matched to the forward gain of the LDO, not requiring calibration. The LDO has a fast load transient response with a recovery time of 6.1 $\mu \text {s}$ and has a quiescent current of 5.6 $\mu \text {A}$ . For a full load transition, the LDO achieves settling with overshoot and undershoot voltages below 27.6 and 36.36 mV, respectively. The LDO is designed and fabricated in a 180 nm bipolar/CMOS/DMOS (BCD) technology. The CFFRC amplifier helps to achieve low quiescent power due to its inherent current mode nature, eliminating the need for supply ripple summing amplifiers and adaptive biasing.

The body weaponized: War, sexual violence and the uncanny

It is today common to argue that rape is a weapon, tool or instrument of warfare. One implication is that armed groups marshal body parts for tactical and strategic ends. In this article, I interrogate this discourse of embodied mobilization to explore how body weaponry has been made intelligible as a medium for sexual violence. First, I show that, despite wide rejection of essentialist models, the penis and penis substitutes continue to occupy a constitutive role in discussions of sexual violence in both political and academic fora, where they are often said to be like weapons, a tendency I term ‘weapon talk’. Second, I trace the image of the body weapon in key threads of feminist theorizing and commentary, to show how the penis has appeared as a ‘basic weapon of force’ in various permutations. Third, I explore the weaponization of the body as it appears in military thought and in the cultural circulation of ideas about the soldiering body in which sexual pleasure and violence are frequently conflated. Building on this foundation, I propose that these literatures collectively describe an uncanny weapon object, and I draw out the significance of this term for feminist security studies and martial empiricism. In short, the uncanny haunts accounts of sexual violence in the collision of sexuality and machinery in the image of a body weapon, in the unsettling designation of sexuality as itself both familiar and dangerous, and in the strange movement of violent bodies across the boundary between wartime and peacetime. A concluding discussion draws out implications and challenges for thinking about embodied violence, advocating renewed attention to the history of weaponization as a fallible and confounding process.