scholarly journals Dual-Wide-Band Dual Polarization Terahertz Linear to Circular Polarization Converters based on Bi-Layered Transmissive Metasurfaces

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 869 ◽  
Author(s):  
Ayesha Kosar Fahad ◽  
Cunjun Ruan ◽  
Kanglong Chen
Keyword(s):  
Circular Polarization ◽  
Wide Band ◽  
Dual Band ◽  
Geometrical Parameters ◽  
Fractional Bandwidth ◽  
Validity And Reliability ◽  
Dual Polarization ◽  
High Frequency Structure Simulator ◽  
Outer Conductor ◽  
The Impact

Transmissive metasurface-based dual-wide-band dual circular polarized operation is needed to facilitate volume and size reduction along with polarization diversity for future THz wireless communication. In this paper, a novel dual-wide-band THz linear polarization to circular polarization (LP-to-CP) converter is proposed using transmissive metasurfaces. It converts incident X polarized waves into transmitted left-hand circular polarized (LHCP) and right-hand circular polarized (RHCP) waves at two frequency bands. The structure consists of bi-layered metasurfaces having an outer conductor square ring and three inner conductor squares diagonally intersecting each other. The proposed converter works equally well with incident Y polarizations. Operational bandwidths for the dual-band LP-to-CP are 1.16 THz to 1.634 THz (34% fractional bandwidth) and 3.935 THz to 5.29 THz (29% fractional bandwidth). The electromagnetic simulation was carried out in two industry-standard software packages, High Frequency Structure Simulator (HFSS) and Computer Simulation Technology (CST), using frequency and time domain solvers respectively. Close agreement between results depicts the validity and reliability of the proposed design. The idea is supported by equivalent circuits and physical mechanisms involved in the dual-wide-band dual polarization operation. The impact of different geometrical parameters of the unit cell on the performance of LP-to-CP operation is also investigated.

The Design of Dual Band Circularly Polarized Patch Antenna for Civilian GPS Applications

2013 ◽  
Vol 397-400 ◽  
pp. 1967-1971
Author(s):  
Guo Xing Jiang
Keyword(s):  
Circular Polarization ◽  
Patch Antenna ◽  
Low Cost ◽  
Dual Band ◽  
Patch Antennas ◽  
Dual Frequency ◽  
High Frequency Structure Simulator ◽  
Microstrip Patch Antennas ◽  
Low Profile ◽  
Compact Size

Antenna is all important part of GPS receivers，there is a great need for the design and production of new antennas which are fully compatible with modernized signals. Because of their advantages such as low cost, compact size, low profile，ability to support dual-frequency and circular polarization operation, microstrip patch antennas have become widely used in GPS antenna designs. A circular polarization patch antennas are proposed in the paper. The antenna designed to operate at L1(1575.42MHz) and L5(1176.45MHz)frequency bands. Initially, a comer-truncated patch antenna for GPS L1 operation was designed to validate simulation in Ansoft High Frequency Structure Simulator(HFSS), the results obtained for this antenna were used to design the two proposed antennas,and designed antennas are presented．

Scale Development: Measuring Job-Family Incivility

2019 ◽  
pp. 31-48
Author(s):  
W G S Mahalekamge ◽  
Nilakshi W K Galahitiyawe
Keyword(s):  
Scale Development ◽  
Work Environment ◽  
Development Process ◽  
Workplace Incivility ◽  
Dynamic Processes ◽  
Validity And Reliability ◽  
Development Approach ◽  
The Impact ◽  
Compound Effect

The main contribution of this paper is the development of the job-family incivility scale. This paper seeks to explore the complex inter-relationships between workplace incivility and family incivility dimensions of job-family incivility by examining the dynamic processes by which job-family incivility is initiated and sustained using a scale development approach. In doing so, the paper highlights the absence of valid and reliable measures that estimate the compound effect of workplace incivility and family incivility – referred to as job-family incivility. A scale development process introduced by Quazi et al. (2016) is presented and stages in the construction of the scale are discussed including measures of validity and reliability. The findings of the study demonstrate the validity and reliability of the job-family incivility scale developed by the current researchers. The main aims of this research are to emphasize the impact of workplace incivility and family incivility on the employees in the work environment, and to discuss the techniques that can be used to mitigate such detrimental activities.

THEORETICAL STUDY OF THE EFFECT OF GEOMETRICAL PARAMETERS AND LOCATION OF ROTOR IMPACT ELEMENTS OF AN IMPACT-CENTRIFUGAL GRINDER ON SPEED AND ANGLES OF CRUSHED PARTICLES FLIGHT

2020 ◽  
Keyword(s):  
Granulometric Composition ◽  
Theoretical Study ◽  
Process Efficiency ◽  
Geometrical Parameters ◽  
Grinding Process ◽  
Main Work ◽  
Impact Element ◽  
The Impact ◽  
Positive Effect ◽  
Efficiency Indicators

One of efficiency indicators of grain grinders is grain granulometric composition. The basis of mixed fodder is crushed grain, the particles of which must have a leveled granulometric composition for subsequent mixing and obtaining a high-quality feed mixture. In agricultural production, hammer crushers are widely used, in which the destruction of grain occurs due to the impact of a hinged hammer. The main disadvantage of these crushers is that not the entire surface of the hammers is involved in grinding, thus reduces grinding process efficiency. A slightly different principle of material destruction is laid down in the basis of the proposed design of the shock-centrifugal grinder. Main work is performed by flat impact elements located on the rotor, which serve to accelerate crushed particles with subsequent impact of them on the bump elements. An important step in the design of new constructions of shock-centrifugal grinders is to determine size and location of the impact elements on the rotor, without which the grinding process is not possible. In the calculation method presented, the dependencies for determining the velocities and angles of a single particle flight from the surface of a flat impact element for its specified dimensions are proposed. Two variants of an impact element location on the rotor are considered and analyzed: radial and at an angle in the direction of rotor rotation. As a result of research carried out, it is noted that in the case of inclined position of an impact element on the rotor an increase in flight speed and flight angles change in crushed particles, which gives the opportunity to have a positive effect on grinding process.

A Novel Pentagonal Shaped Planar Inverted-F Antenna for Defense Applications

2019 ◽  
Vol 12 (2) ◽  
pp. 95-100
Author(s):  
Purnima Sharma ◽  
Akshi Kotecha ◽  
Rama Choudhary ◽  
Partha Pratim Bhattacharya
Keyword(s):  
Mobile Communication ◽  
Satellite Communication ◽  
Dual Band ◽  
Vehicular Communication ◽  
Radio Frequency Field ◽  
Wireless Applications ◽  
High Frequency Structure Simulator ◽  
Low Profile ◽  
Radar Satellite ◽  
5 Ghz

Background: The Planar Inverted-F Antenna (PIFA) is most widely used for wireless communication applications due to its unique properties as low Specific Absorption Rate, low profile geometry and easy fabrication. In literature a number of multiband PIFA designs are available that support various wireless applications in mobile communication, satellite communication and radio frequency field. Methods: In this paper, a miniature sized planar inverted-F antenna has been proposed for dual-band operation. The antenna consists of an asymmetrical pentagonal shaped patch over an FR4 substrate. The overall antenna dimension is 10 × 10 × 3 mm3 and resonates at 5.7 GHz frequency. A modification is done in the patch structure by introducing an asymmetrical pentagon slot. Results: The proposed pentagonal antenna resonates at 5.7 GHz frequency. Further, modified antenna resonates at two bands. The lower band resonates at 5 GHz and having a bandwidth of 1.5 GHz. This band corresponds to C-band, which is suitable for satellite communication. The upper band is at 7.9 GHz with a bandwidth of 500 MHz. Performance parameters such as return loss, VSWR, input impedance and radiation pattern are obtained and analysed using ANSYS High- Frequency Structure Simulator. The radiation patterns obtained are directional, which are suitable for mobile communication. Conclusion: The antenna is compact in size and suitable for radar, satellite and vehicular communication.

scholarly journals A circular polarization survey for radio stars with the Australian SKA Pathfinder

2021 ◽  
Vol 502 (4) ◽  
pp. 5438-5454
Author(s):  
Joshua Pritchard ◽  
Tara Murphy ◽  
Andrew Zic ◽  
Christene Lynch ◽  
George Heald ◽  
...  
Keyword(s):  
Radio Emission ◽  
Brightness Temperature ◽  
Circular Polarization ◽  
Flux Density ◽  
Wide Band ◽  
M Dwarfs ◽  
Square Kilometre Array ◽  
Population Statistics ◽  
Chemically Peculiar ◽  
Radio Stars

ABSTRACT We present results from a circular polarization survey for radio stars in the Rapid ASKAP Continuum Survey (RACS). RACS is a survey of the entire sky south of δ = +41○ being conducted with the Australian Square Kilometre Array Pathfinder telescope (ASKAP) over a 288 MHz wide band centred on 887.5 MHz. The data we analyse include Stokes I and V polarization products to an RMS sensitivity of 250 μJy PSF−1. We searched RACS for sources with fractional circular polarization above 6 per cent, and after excluding imaging artefacts, polarization leakage, and known pulsars we identified radio emission coincident with 33 known stars. These range from M-dwarfs through to magnetic, chemically peculiar A- and B-type stars. Some of these are well-known radio stars such as YZ CMi and CU Vir, but 23 have no previous radio detections. We report the flux density and derived brightness temperature of these detections and discuss the nature of the radio emission. We also discuss the implications of our results for the population statistics of radio stars in the context of future ASKAP and Square Kilometre Array surveys.

scholarly journals Validity and reliability testing of the Toddler and Infant (TANDI) Health Related Quality of Life instrument for very young children

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Janine Verstraete ◽  
Lebogang Ramma ◽  
Jennifer Jelsma
Keyword(s):  
Quality Of Life ◽  
Health Related Quality ◽  
Validity And Reliability ◽  
Spearman's Rho ◽  
Spearman’S Rho ◽  
Related Quality ◽  
Health Related ◽  
Six Dimensions ◽  
The Impact

Abstract Background Despite the high burden of disease in younger children there are few tools specifically designed to estimate Health Related Quality of Life (HRQoL) in children younger than 3 years of age. A previous paper described the process of identifying a pool of items which might be suitable for measuring HRQoL of children aged 0–3 years. The current paper describes how the items were pruned and the final draft of the measure, Toddler and Infant (TANDI) Health Related Quality of Life, was tested for validity and reliability. Methods A sample of 187 caregivers of children 1–36 months of age were recruited which included children who were either acutely ill (AI), chronically ill (CI) or from the general school going population (GP). The TANDI, an experimental version of the EQ-5D-Y proxy, included six dimensions with three levels of report and general health measured on a Visual Analogue Scale (VAS) from 0 to 100. The content validity had been established during the development of the instrument. The TANDI, Ages and Stages Questionnaire (ASQ), Faces, Leg, Activity, Cry, Consolabilty (FLACC) or Neonatal Infant Pain Scale (NIPS) and a self-designed dietary information questionnaire were administered at baseline. The TANDI was administered 1 week later in GP children to establish test-retest reliability. The distribution of dimension scores, Cronbach’s alpha, rotated varimax factor analysis, Spearman’s Rho Correlation, the intraclass correlation coefficient, Pearson’s correlation, analysis of variance and regression analysis were used to explore the reliability, and validity of the TANDI. Results Concurrent validity of the different dimensions was tested between the TANDI and other instruments. The Spearman’s Rho coefficients were significant and moderate to strong for dimensions of activity and participation and significant and weak for items of body functions. Known groups were compared and children with acute illness had the lowest ranked VAS (median 60, range 0–100), indicating worse HRQoL. The six dimensions of the TANDI were tested for internal consistency and reliability and the Cronbach’s α as 0.83. Test-retest results showed no variance for dimension scores of movement and play, and high agreement for pain (83%), relationships (87%), communication (83%) and eating (74%). The scores were highly correlated for the VAS (ICC = 0.76; p < 0.001). Conclusion The TANDI was found to be valid and reliable for use with children aged 1–36 months in South Africa. It is recommended that the TANDI be included in future research to further investigate HRQoL and the impact of interventions in this vulnerable age group. It is further recommended that future testing be done to assess the feasibility, clinical utility, and cross-cultural validity of the measure and to include international input in further development.

Influence of nozzle exit geometrical parameters on supersonic jet decay

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Prasanta Kumar Mohanta ◽  
B. T. N. Sridhar ◽  
R. K. Mishra
Keyword(s):  
Aspect Ratio ◽  
Nozzle Exit ◽  
Ambient Air ◽  
Schlieren Image ◽  
Geometrical Parameters ◽  
Image Study ◽  
Aspect Ratios ◽  
Core Length ◽  
Supersonic Core Length ◽  
The Impact

Abstract Experiments and simulations were carried on C-D nozzles with four different exit geometry aspect ratios to investigate the impact of supersonic decay characteristics. Rectangular and elliptical exit geometries were considered for the study with various aspect ratios. Numerical simulations and Schlieren image study were studied and found the agreeable logical physics of decay and spread characteristics. The supersonic core decay was found to be of different length for different exit geometry aspect ratio, though the throat to exit area ratio was kept constant to maintain the same exit Mach number. The impact of nozzle exit aspect ratio geometry was responsible to enhance the mixing of primary flow with ambient air, without requiring a secondary method to increase the mixing characteristics. The higher aspect ratio resulted in better mixing when compared to lower aspect ratio exit geometry, which led to reduction in supersonic core length. The behavior of core length reduction gives the identical signature for both under-expanded and over-expanded cases. The results revealed that higher aspect ratio of the exit geometry produced smaller supersonic core length. The aspect ratio of cross section in divergent section of the nozzle was maintained constant from throat to exit to reduce flow losses.

A HMSIW Dual-band Dual-polarization Cavity-backed Antenna

2020 ◽  
Author(s):  
Chuanyun Wang ◽  
Xiqiang Zhang ◽  
Lina Wang ◽  
Haiwen Liu ◽  
Zhiwen Han ◽  
...  
Keyword(s):  
Dual Band ◽  
Dual Polarization

scholarly journals High-Efficiency Polarizer Reflectarray Antennas for Data Transmission Links from a CubeSat

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1802
Author(s):  
Eduardo Martinez-de-Rioja ◽  
Daniel Martinez-de-Rioja ◽  
Rafael López-Sáez ◽  
Ignacio Linares ◽  
Jose A. Encinar
Keyword(s):  
Circular Polarization ◽  
Data Transmission ◽  
High Efficiency ◽  
High Gain ◽  
Dual Band ◽  
Left Handed ◽  
Linearly Polarized ◽  
Flat Profile ◽  
First Time ◽  
Collimated Beam

This paper presents two designs of high-efficiency polarizer reflectarray antennas able to generate a collimated beam in dual-circular polarization using a linearly polarized feed, with application to high-gain antennas for data transmission links from a Cubesat. First, an 18 cm × 18 cm polarizer reflectarray operating in the 17.2–22.7 GHz band has been designed, fabricated, and tested. The measurements of the prototype show an aperture efficiency of 52.7% for right-handed circular polarization (RHCP) and 57.3% for left-handed circular polarization (LHCP), both values higher than those previously reported in related works. Then, a dual-band polarizer reflectarray is presented for the first time, which operates in dual-CP in the frequency bands of 20 GHz and 30 GHz. The proposed antenna technology enables a reduction of the complexity and cost of the feed chain to operate in dual-CP, as a linear-to-circular polarizer is no longer required. This property, combined with the lightweight, flat profile and low fabrication cost of printed reflectarrays, makes the proposed antennas good candidates for Cubesat applications.

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