Power Divider Research Articles

Changed Reality, Changed Positions: The Case Study of Eritrean Women Refugees in Times of Global Pandemic

ABSTRACTThis article examines the emerging position of women refugees during a global crisis. On the basis of an empirical study of the Eritrean community in Tel Aviv, Israel, I analysed the ways in which gender identity is formulated and recreated following the social and economic restrictions of the Covid‐19 pandemic. In contrast to previous literature which has highlighted men's central position in forced migrant communities, I suggest viewing the global pandemic as an accelerator of women's presence in two circles of belonging: the family unit and the Eritrean community. I argue that structural changes imposed by the pandemic have established new gender roles and divisions of power, positioning women as a source of authority and a subject of choice. As a significant proportion of Eritrean men lost their income during the pandemic, they were forced to adopt a different role within the family unit. Eritrean women, on the other hand, managed to keep their jobs and became the family's sole provider. In addition to increasing their family's economic dependence on them, Eritrean women also became central figures in their community through the creation of new social networks designed to satisfy the emotional and economic needs of its members. This has enabled women refugees to reinforce their social mobility and become relatively autonomous.

Hetero‐Dimensional Micro‐Nano Architectures Toward Electromagnetic Devices and Hybrid Energy Transport

AbstractHuman spaceflight, lunar exploration projects, and interstellar travel are the grand visions of human exploration of the universe. However, the energy sustainability of these projects is a concern. Electromagnetic functional materials and devices are expected to fulfill their potential in electronic communication and energy utilization. Herein, hetero‐dimensional micro‐nano architectures composed of Cu3Se2 microspheres and reduced graphene oxide (rGO) sheets are fabricated for the first time by the sacrificial template method, anion substitution engineering, electrostatic adsorption, and reduction‐oxidation reaction. Based on the excellent electromagnetic response of the composites, they exhibit strong and ultra‐wide microwave absorption ability with the effective absorption bandwidth (EAB) reaching 8.24 GHz at a thickness of 2.2 mm. In addition, an electromagnetic metamaterial with an EAB to ≈13.5 GHz is proposed, exhibiting significant properties. More significantly, the composites can be used to construct a range of electromagnetic devices: a spiral antenna with adjustable return loss and gain, with a maximum gain of up to 2.5 dBi; a microstrip power divider that can efficiently split the input signal into four equal parts and output it; a hybridized energy transport device can convert and store electromagnetic energy. This work provides new inspiration for electromagnetic protection, electronic communication, and energy development.

Multilayer substrate integrated waveguide six-port junctions with embedded resistive films

Abstract This article deals with multilayer substrate integrated waveguide (SIW) six-port junctions with embedded carbon resistive films. SIW six-ports usually employ reactive power dividers, which degrade the amplitude and phase balance when the six-port is terminated with mismatched power detectors. The associated impairments are studied and two SIW six-port junctions with improved isolation and output matching are designed for K-/Ka-band applications to overcome these limitations. The proposed designs differ with respect to the configuration of the output ports making the underlying six-port topology applicable for different layout requirements. Measurements of the fabricated components validate the concept. The six-ports are compact, fully shielded and can be integrated in multilayer printed circuit boards.

Security enhancement for NOMA-PON with 2D cellular automata and Turing pattern cascading scramble aided fixed-point extended logistic chaotic encryption

The non-orthogonal multiple access-passive optical network (NOMA-PON) is facing the dual security threats of primary user interference and unauthorized third-party user eavesdropping, so efficient data security enhancement techniques are crucial. To solve these problems, we propose a fixed-point extended (FE)-logistic chaotic mapping to reduce the computational complexity while employing a two-dimensional (2D) cellular automata (CA) and Turing pattern (TP) cascading scramble (CA-TPCS) encryption algorithm to further improve the sensitivity of the NOMA-PON system. The CA-TPCS consists of 2D-CA dynamic bit encryption and Turing symbol substitution (TSS). By using FE chaos to construct 2D-CA and adopting index sort to extract the TSS matrix, dynamic diffusion of bits and scrambling of a 2D symbol matrix are achieved. To ensure the key privacy, we employ a dual key mechanism, and uplink data is introduced as the private key. To verify the feasibility of the proposed method, a simulation validation is built on a 17.6 Gb/s power division multiplexing-orthogonal frequency division multiplexing (PDM-OFDM) NOMA-PON system transmitted over 25 km standard single mode fiber (SSMF). The results show that the proposed scheme has no effect on the optimal power allocation rate (PAR) values and the values are all 3. Meanwhile, the receiver sensitivity gains of 0.2 and 0.3 dB are obtained for high-power and low-power users after encryption. The ciphertext has good diffusion and statistical properties, and the key space is flexibly controlled by the FE precision f, the length l of the transmitted bit, and the size T of the TP, with the value of 22f+l+T×T. The results show that the proposed scheme is not only very compatible with PDM technology but also can realize the dual defense of internal aggression and external aggression. It has a good application prospect in the future NOMA-PON.

TAIWAN (ROC) MUST ROCK! WHY TAIWAN'S CASE MATTERS?

The author discusses the subjectivity of Taiwan in the article. It must be remember that Taiwan is unrecognized as a state according to international public law. First then, author describes the theories of state elements. She also briefly characterizes the division of power in Taiwan. Then, she points to the organization of the cybersecurity system and methods of combating disinformation as an example of the efficient functioning of Taiwan as a state.

A 3D-printing metasurface-augmented half-circle Maxwell fisheye lens for millimetre-wave analogue beamforming

Abstract This article presents a 2D metasurface-augmented half-circle Maxwell fisheye lens (HMFL) designed to move its focal axis to a targeted direction with a maximum elevation angle of 45 degrees, suitable for switches and power division networks in the millimetre wave (mmWave) band. This metasurface-augmented beamformer enables consistent analogue performance across a bandwidth of 22 - 32 GHz. The proposed beamformer features a reflective metasurface consisting of 2x40 Phoenix unit cells and is integrated with a 10-dielectric zone HMFL in the diameter segment opposite the antenna source. A horn antenna feed is used for excitation in normal and oblique incidences of -15 and -30 degrees. The designed lens prototype was fabricated with 3D-printing technology and printed metasurfaces for several particular cases of focal displacement. The measurements of the proposed HMFL beamformer are presented, demonstrating a close correlation between simulated and experimental results.

On the lossy character of Y-branches and their analogy to Wilkinson power dividers

Y-branches are commonly used devices for power splitting and combining in various technological applications. Despite their widespread use, research on their design and analysis has been mostly focused on their characterization based on reflection and transmission when operating as power dividers, leaving aside an exhaustive consideration of all their possible modes of operation. Also, it has not been fully recognized that these devices have intrinsic losses. If these losses are not properly managed, they can negatively impact the network, but also open the door to new opportunities. In this context, this paper examines Y-bifurcation properties and their connection to Wilkinson’s power dividers. Additionally, through numerical analysis, we demonstrate the possibility of integrating these devices into more complex optical networks. We use them as components in generalized power dividers and analog optical computational systems designed to filter out the maximum common phase component and avoid backward reflections for any input signal.

An independent continuously scannable dual-beam liquid crystal phased array antenna for Ku-band

ABSTRACT An independent continuously scannable dual-beam liquid crystal (LC) phased array antenna (DBLCPA) operating in the Ku-band is proposed for the first time in this article. Eight right-hand circularly polarised microstrip patch antennas (RHCPMPAs), four 90° hybrid couplers, eight liquid crystal phase shifters (LCPSs), and two power dividers form the proposed array antenna, which utilises the dynamic phase difference between LCPSs and the inherent phase difference of the 90° hybrid coupler to achieve scannable dual-beam driving. The proposed DBLCPA can be conceptualised as two one-dimensional phased array systems. By adjusting the phase difference of each group of LCPSs respectively, the two independent scannable beams can be achieved simultaneously. The S-parameters and far-field pattern of the fabricated antenna array are measured and analysed. The measured S 11 and S 22 of the DBLCPA is below −10 dB and the isolation is better than 10 dB at 11.5–12.5 GHz. The two beams can achieve independent continuous scanning in E-plane, in which the left beam is scannable between 0° and 40°, and the right beam is scannable among 0° to −40°. The measured maximum dual-beam gain of the antenna array is 11.3 dBi, while the axial ratio is less than 3 dB.

Design of four-port antenna with two sets of orthogonal CO-CP performance

This work presents a four-port in-band full-duplex (IBFD) antenna that allows transmitting and receiving two sets of orthogonal co-circularly polarized signals, facilitating IBFD system applications. The single-element antenna is constructed using a six-port isolation network (SPIN) without the need for circulators, helping to reduce cost and facilitate integration. The transmit-receive isolation is accomplished via the isolation of power dividers and the cancellation guided by the coupling path of SPIN. The microwave network analysis method perfectly analyzes the operating mechanism of isolation and orthogonal co-circular polarization. The measured results confirm that this design achieves excellent two sets of orthogonal co-circular polarization. The measured results show that the 10-dB impedance bandwidth is 24.2%, the 3-dB axial-ratio bandwidth is 23.5%, and the measured 30-dB isolation bandwidth is 3.52-4.15 GHz (16.4%) with a maximum isolation of 53.2 dB.

Highly selective filtering power divider using substrate integrated waveguide technique for radar applications

<p><span>This article exhibits a filtering power divider designed with substrate integrated waveguide (SIW) technique, having the power dividing as well as filtering functionalities. In the design band-pass performance is realized by merging SIW structure having high-pass response and complementary split ring resonator (CSRRs) with parallel tank LC resonant response and the dumbbells shape defected ground structure (DGS) with high out of band rejection characteristics. The anticipated structure serves as both a power divider and a filter, it reduces both the cost and the size of the system. Structure is constructed and tested to confirm the design functionality. The measurement result shows the return loss of -25.94 dB with 3-dB fractional bandwidth of 2.85% at 14 GHz.</span></p>

Size Reduction of Wilkinson Power Divider using a Combination of Parallel Coupled Lines and Defective Microstrip Structures

Size Reduction of Wilkinson Power Divider using a Combination of Parallel Coupled Lines and Defective Microstrip Structures

Full-space trifunctional metasurface with independent amplitude/phase control and its application to asymmetric spatial power divider

ABSTRACT In this paper, a dual-frequency trifunctional metasurface (MS) consisting of three metal layers printed on two substrate layers is proposed. The low-frequency transmitted wave is regulated through a C-shaped slot etched in middle layer and C-shaped patches in top/bottom metal layers. High-frequency reflected waves can be regulate by the C-shaped slot etched in ring patch in top/bottom layers. Also, in top/bottom layers, C-shaped patches and slots operate in electric and magnetic resonant modes that the interference between transmitted and reflected waves is suppressed. This MS integrates three independent working modes, that is to say, it can reflect x-polarized waves propagating along +z/-z direction at high frequency and transmit x-polarized low-frequency waves from -z direction. Meanwhile, 360° phase coverage and continuous amplitude control from 0 to 1 can be independently achieved in three working modes. Based on this MS, an asymmetric spatial power divider is designed and measured. The measured results are consistent with the designed goals.

Broadband 3-bit coding metasurface antenna with integrated radiation and scattering performance

This paper presents the design of an integrated metasurface antenna, which combines a central radiating patch with a quadru-arc (QAS) structure. The metasurface antenna simultaneously achieves high-gain radiation and complex scattering functionality. The modulation of the radiation function is primarily achieved through phase manipulation of the power division feed network, while modulation of the X-polarization scattering function is mainly accomplished by adjusting the arc of the QAS. The effectiveness of this design is verified by designing two metasurface antennas with distinct functionalities. The feed network phases are arranged in a checkerboard pattern in the first approach, resulting in four-beam radiation with a gain of 16 dBi per beam. Additionally, the scattering component utilizes eight scattering structures with a phase difference of 45 degrees to form a 3-bit coding, enabling vortex beam scattering. The second configuration arranges the feed network in phase with the deflected beam, resulting in a deflected beam radiation pattern characterized by a gain of 22.3 dBi. The scattering function is optimized using a simulated annealing-genetic algorithm for phase alignment, resulting in the achievement of RCS reduction across a wide bandwidth range of 8-24 GHz. The proposed metasurface antenna is ultimately fabricated and subjected to rigorous measurements.

Gender Role of Household Decision Making (A case study Namobudda Kavre)

Gender roles in household decision making refer to the traditional division of responsibilities and decision-making power between men and women within a family or household. Historically, many societies have adhered to traditional gender roles, where men are often considered the primary decision-makers, particularly in matters related to finances and major family decisions. Women, on the other hand, have often been assigned the roles of managing the household, taking care of children, and dealing with domestic matters. However, it's important to recognize that gender roles are not fixed and vary significantly across cultures, regions, and individual households. Moreover, over time, many societies have witnessed a shift in traditional gender roles, with more emphasis on gender equality and shared decision making. The main purpose of this research was to understand the perception of people regarding the evolvement of gender roles in any household decision making. A Descriptive Cross Sectional study method was used. Altogether, 40 respondents were selected through purposive sampling method, questionnaires, Face to face interview, Informal focused group discussion; Key informant interview method was used using Structured Questionnaire to collect data from respondents. Data analysis was done through MS Excel. It is revealed from the research Gender roles in household decision making refer to the traditional division of responsibilities and decision-making power between men and women within a family or household. Historically, many societies have adhered to traditional gender roles, where men are often considered the primary decision-makers, particularly in matters related to finances and major family decisions. Women, on the other hand, have often been assigned the roles of managing the household, taking care of children, and dealing with domestic matters. However, it's important to recognize that gender roles are not fixed and vary significantly across cultures, regions, and individual households. Moreover, over time, many societies have witnessed a shift in traditional gender roles, with more emphasis on gender equality and shared decision making

Trust at the border: identifying risk and assessing credibility on reality television

AbstractEvery day, officers working at international airports investigate potential risks to state safety and security. But how do they decide who they can trust, and also ensure that the broader public trusts them to conduct this work? This article explores these questions through an examination of the reality television show Border Security: Australia's Front Line. Through critical discourse analysis of a collection of 108 televised airport encounters, we explore the aspects of communication, behaviour, and identity made salient in officers’ evaluations of passengers’ credibility and critically examine the assumptions underlying them. Further, we consider how power and role divisions are implicated in the construction of passenger and officer credibility, both within border encounters and in discourses about them. Our analysis makes a novel contribution to the literature on credibility assessments in intercultural communication, demonstrating how an institutional and social ‘culture of disbelief’ is constructed vis‐à‐vis certain groups through seemingly banal border work.

A novel miniaturized microstrip filtering power divider with high selectivity based on composite right/left-handed (CRLH) concept

Abstract This paper proposes a compact microstrip filtering power divider (FPD) with high selectivity and equal power division ratios based on the composite right/left-handed (CRLH) concept. The proposed equal microstrip FPD is designed by cascading two CRLH unit cells and a grounded via hole. The proposed CRLH unit cell is realized by an interdigital capacitor loaded between two transmission lines (TL) on the upper metal layer and the fractal/meander complementary split-ring resonator (FMCSRR) on the ground plane. The grounded via hole has been used to improve frequency selectivity and out-of-band rejection of the proposed microstrip FPD. The equivalent circuit model compared with full-wave simulation results of the proposed microstrip FPD has been provided. The proposed microstrip FPD has been fabricated and measured, and a good agreement has been found between the simulation and measurement results. The proposed microstrip FPD has a passband covering 2.38–2.45 GHz, and its measured 3 dB fractional bandwidth is about 2.9 %. The total size of the proposed microstrip FPD is 0.17 λ g × 0.07 λ g. Compared with other reported FPDs, the presented microstrip FPD has many advantages like compact size, low loss, easy fabrication, extremely sharp rejection skirts around the desired passband and high selectivity.

Topological State in Heterostructured Gap Waveguides and Their Transitions to Classical Transmission Line

AbstractGap waveguides play a crucial role in millimeter‐wave information transmission and processing for next‐generation wireless communication and radar sensing systems. However, they suffer from challenges, such as reflection and scattering losses at sharp bends and defects. While topological photonic crystals offer innovative solutions for robust signal transmission, their localized interface states and unique electromagnetic modes pose compatibility challenges with practical circuits and systems. In this paper, a novel heterostructured gap waveguide support valley‐locked topological guided wave transport is introduced. This design ensures robust propagation against defects and bends while maintaining compatibility with classical transmission lines. Its topological characteristic reduce sensitivity to fabrication and assembly errors. More importantly, an efficient transition structure is developed to seamlessly convert quasi‐transverse electromagnetic (quasi‐TEM) modes in planar transmission lines to topological guided wave states, thereby effectively exciting topological waves. All theoretical predictions are quantitatively verified by the simulations and experiments at millimeter wave frequency. This heterostructured gap waveguide can find unique applications, such as power divider, as verified numerically. By leveraging topological principles, the proposed gap waveguide offers a significant performance boost for antennas and passive/active components in millimeter‐wave applications, including automotive radar, 5G communication, and synthetic‐aperture radar for imaging.

The (Il)legitimacy of Constitutional Amendments in Africa and Democratic Backsliding

Abstract In many African countries with hegemonic-party or de facto one-party systems, political leaders have historically exploited ostensibly proper constitutional amendments to undermine constitutionalism, a practice raising questions about the legitimacy, or lack thereof, of such amendments. This article argues that amendment legitimacy is contingent on achieving ‘broad consensus’, a concept endorsed by the African Charter on Democracy, Elections and Governance. Traditional amendment procedures, such as supermajorities and referendums, while crucial, have proven to be imperfect proxies for ensuring such broad consensus. To more effectively safeguard the core constitutional rules of democratic governance, this article contends that political parties must be recognised as key sites of power division and checks and balances. Accordingly, constitutional amendment procedures should require some level of cross-party approval for key amendments, thus preventing individual political groups, regardless of their dominance, from unilaterally altering fundamental rules of the game. This approach would not only enhance the legitimacy of amendments but also serve as a safeguard against contemporary forms of democratic backsliding, where incumbents exploit formal processes to undermine democratic competition. While this process might make constitutional changes more difficult, it would apply only to a narrow set of fundamental aspects of constitutional democracy. Moreover, it does not necessarily conflict with popular self-governance (and its majoritarian expression), but instead calls for an inclusive re-imagining of majoritarianism.

Indigenous Development of MIC-Based C-Band Dual Chain Down Converter Unit for GEOSAT- Spacecraft Checkout System

As part of miniaturization, the development work for the C-band dual-chain down converter, which is extensively used in TM (Telemetry) data acquisition system in GEOSAT spacecraft checkout system has been taken up in MIC (Microwave Integrated Circuit) approach using microstrip line structure. A prototype unit is realized using standard surface mount devices (SMD) and few indigenously developed MIC components namely, the directional couplers, the power dividers etc. The MIC-based down converter module, which forms the heart of the unit is housed in an Aluminium milled box having the dimension of 150 x 150 x 25 mm3. Except internal Local Oscillator (LO), RF Switches and Power supply, all other circuitry are mounted withinthis milled box which is housed in 1U chassis. It meets all the requirements of a conventional down converter. The paper describes the salient features of the unit, its detailed design approach and realization plan and finally the test and evaluation results of the prototype unit developed indigenously.

Reconfigurable dielectric resonator antenna and array with frequency and polarization flexibility

To implement frequency and polarization hybrid reconfiguration, a 4 × 4 array has been investigated. The radiation elements of the antenna array consist of cylindrical dielectric resonators, Wilkinson power divider, PIN diode, and dielectric substrate. The PIN diode controls the states of each branch in the Wilkinson power divider to achieve frequency and polarization reconfigurability. To verify the feasibility of the design, a fabricated sample of the proposed antenna array has been measured. The results demonstrate that the antenna array can be switched freely between its operating frequencies and polarizations. It operates within a bandwidth of 1.93 to 4.6 GHz for frequency reconfiguration, and three common polarization states—linear polarization, left-handed circular polarization, and right-handed circular polarization—can be continuously tuned from 2.96 to 3.39 GHz.