scholarly journals Asymptotic Study of the Radiation Operator for the Strip Current in Near Zone

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 911
Author(s):  
Rocco Pierri ◽  
Raffaele Moretta
Keyword(s):  
Eigenvalue Problem ◽  
Near Field ◽  
Measurement Techniques ◽  
Sampling Strategy ◽  
Singular Values ◽  
Continuous Model ◽  
Sampling Theory ◽  
Theory Approach ◽  
Near Zone ◽  
Band Limited

In this paper, we address the problem of how to efficiently sample the radiated field in the framework of near-field measurement techniques. In particular, the aim of the article is to find a sampling strategy for which the discretized model exhibits the same singular values of the continuous problem. The study is done with reference to a strip current whose radiated electric field is observed in the near zone over a bounded line parallel to the source. Differently from far zone configurations, the kernel of the related eigenvalue problem is not of convolution type, and not band-limited. Hence, the sampling-theory approach cannot be directly applied to establish how to efficiently collect the data. In order to surmount this drawback, we first use an asymptotic approach to explicit the kernel of the eigenvalue problem. After, by exploiting a warping technique, we recast the original eigenvalue problem in a new one. The latter, if the observation domain is not too large, involves a convolution operator with a band-limited kernel. Hence, in this case the sampling-theory approach can be applied, and the optimal locations of the sampling points can be found. Differently, if the observation domain is very extended, the kernel of the new eigenvalue problem is still not convolution. In this last case, in order to establish how to discretize the continuous model, we perform a numerical analysis.

scholarly journals On the Sampling of the Fresnel Field Intensity over a Full Angular Sector

Electronics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 832
Author(s):  
Rocco Pierri ◽  
Raffaele Moretta
Keyword(s):  
Discrete Model ◽  
Fresnel Zone ◽  
Singular Values ◽  
Linear Representation ◽  
Continuous Model ◽  
Sampling Theorem ◽  
Theory Approach ◽  
Discretization Scheme ◽  
Lifting Technique ◽  
The Fourier Transform

In this article, the question of how to sample the square amplitude of the radiated field in the framework of phaseless antenna diagnostics is addressed. In particular, the goal of the article is to find a discretization scheme that exploits a non-redundant number of samples and returns a discrete model whose mathematical properties are similar to those of the continuous one. To this end, at first, the lifting technique is used to obtain a linear representation of the square amplitude of the radiated field. Later, a discretization scheme based on the Shannon sampling theorem is exploited to discretize the continuous model. More in detail, the kernel of the related eigenvalue problem is first recast as the Fourier transform of a window function, and after, it is evaluated. Finally, the sampling theory approach is applied to obtain a discrete model whose singular values approximate all the relevant singular values of the continuous linear model. The study refers to a strip source whose square magnitude of the radiated field is observed in the Fresnel zone over a 2D observation domain.

scholarly journals Near-Field Warping Sampling Scheme for Broad-Side Antenna Characterization

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1047
Author(s):  
Maria Maisto ◽  
Rocco Pierri ◽  
Raffaele Solimene
Keyword(s):  
Near Field ◽  
Singular Values ◽  
Sampling Theorem ◽  
Sampling Scheme ◽  
Limited Function ◽  
Field Radiation ◽  
Planar Source ◽  
Standard Sampling ◽  
Band Limited ◽  
Band Limited Function

In this paper the problem of sampling the field radiated by a planar source observed over a finite planar aperture located in the near-field is addressed. The problem is cast as the determination of the spatial measurement positions which allow us to discretize the radiation problem so that the singular values of the radiation operator are well-approximated. More in detail, thanks to a suitably warping transformation of the observation variables, the kernel function of the relevant operator is approximated by a band-limited function and hence the sampling theorem applied to achieved discretization. It results in the sampling points having to be non-linearity arranged across the measurement aperture and their number can be considerably lowered as compared to more standard sampling approach. It is shown that the proposed sampling scheme works well for measurement apertures that are not too large as compared to the source’s size. As a consequence, the method appears better suited for broad-side large antenna whose radiated field is mainly concentrated in front of the antenna. A numerical analysis is included to check the theoretical findings and to study the trade-off between the field accuracy representation (over the measurement aperture) and the truncation error in the estimated far-field radiation pattern.

scholarly journals NDF of the near-zone field on a line perpendicular to the source

2021 ◽  
Author(s):  
Rocco Pierri ◽  
Raffaele Moretta
Keyword(s):  
Eigenvalue Problem ◽  
Closed Form ◽  
Degrees Of Freedom ◽  
Adjoint Operator ◽  
Critical Index ◽  
Singular Values ◽  
Near Zone ◽  
Zone Field

<div>In this paper, the problem of computing the number of degrees of freedom (NDF) of the field radiated by a strip current along all the possible lines orthogonal to the source is addressed.</div><div>As well known, the NDF is equal to the number of singular values of the radiation operator that are before a critical index at which they abrupt decay. Unfortunately, in the considered case, the solution of the associate eigenvalue problem is not known in closed-form, and this prevents us from directly evaluating the singular values of the radiation operator. To overcome this drawback, a weighted adjoint operator is exploited. The latter allows obtaining an eigenvalue problem whose solution is known in closed-form but, at the same time, it modifies the singular values behavior. However, since the change affects only the dynamics of the singular values but not the critical index at which they abrupt decay, the NDF of the radiated field can be analytically estimated by resorting to the weighted adjoint operator. <br></div>

scholarly journals Hybrid multilevel plane wave based near-field far-field transformation utilising combined near- and far-field translations

2009 ◽  
Vol 7 ◽  
pp. 17-22 ◽  
Author(s):  
C. H. Schmidt ◽  
T. F. Eibert
Keyword(s):  
Near Field ◽  
Measurement Techniques ◽  
Plane Waves ◽  
Low Complexity ◽  
Far Field ◽  
Computation Complexity ◽  
Low Frequencies ◽  
Field Transformation ◽  
Translation Operators ◽  
Equivalent Sources

Abstract. The radiation of large antennas and those operating at low frequencies can be determined efficiently by near-field measurement techniques and a subsequent near-field far-field transformation. Various approaches and algorithms have been researched but for electrically large antennas and irregular measurement contours advanced algorithms with low computation complexity are required. In this paper an algorithm employing plane waves as equivalent sources and utilising efficient diagonal translation operators is presented. The efficiency is further enhanced using simple far-field translations in combination with the expensive near-field translations. In this way a low complexity near-field transformation is achieved, which works for arbitrary sample point distributions and incorporates a full probe correction without increasing the complexity.

scholarly journals Hepatitis C and the Social Hierarchy: How Stigma Is Built in Rural Communities

2018 ◽  
Author(s):  
Charley Henderson ◽  
Atsuko Kawakami
Keyword(s):  
Hepatitis C ◽  
Rural Communities ◽  
Sampling Strategy ◽  
Extended Period ◽  
Social Hierarchy ◽  
Theory Approach ◽  
Snowball Sampling ◽  
Common View ◽  
The Social ◽  
Community Issues

Although Hepatitis C has profound impacts on individuals living in communities, most research has been conducted in a hospital or laboratory setting. Additionally, there is a lack of research exploring the social effects of Hepatitis C in rural communities. In this qualitative study, we focus on perceptions on Hepatitis C within a rural community, describe how the local residents perceive social hierarchy within their community, and explore the process of stigma building. Informed by a grounded theory approach, we employed a snowball sampling strategy in a southern rural area to conduct in-depth, open-ended interviews. In our findings we describe how local restaurants were often utilized as places to exchange personal opinions on various community issues among the upper hierarchical members, consider the ways social hierarchy influences people’s perceptions, and explore community members’ response to the problem of ignored viral infections within the community. We found the community leaders are earning the trust by living in the community for an extended period of time; therefore, they tend to be elderly yet remain active as members of various committees. Additionally, we argue that the common view of “family-like support” in rural communities is largely a myth; it is a romanticized view of the rural living held and perpetuated by the upper-class people in the community. Therefore, instead of depending on idealized or imaginary social support, rural communities need to consider organizing a system of formal support.

scholarly journals A Sampling Theory Approach for Continuous ARMA Identification

2011 ◽  
Vol 59 (10) ◽  
pp. 4620-4634 ◽  
Author(s):  
Hagai Kirshner ◽  
Simona Maggio ◽  
Michael Unser
Keyword(s):  
Sampling Theory ◽  
Theory Approach

scholarly journals POLA KOMUNIKASI PASANGAN SUAMI ISTRI DALAM TEKANAN PASCA MELAHIRKAN DI KOTA BANDAR LAMPUNG

2021 ◽  
Vol 8 (01) ◽  
pp. 1-10
Author(s):  
Kinantri Puspa Sari ◽  
Maulana Rezi Ramadhana
Keyword(s):  
Postpartum Period ◽  
Sampling Strategy ◽  
Married Couples ◽  
Communication Patterns ◽  
Transitional Period ◽  
Communication Pattern ◽  
Theory Approach ◽  
Snowball Sampling ◽  
Open Communication ◽  
Postpartum Stress

The postpartum period is a transitional period experienced by married couples who require adjustments to the presence of changes in their relationship, especially when the wife is experiencing postpartum stress (depression) during that period. The postpartum period causes changes in conditions followed by changing roles and responsibilities, which can affect the communication relationship between partners. This study focuses on communication patterns of married couples in postpartum pressure using the Interpersonal Communication Patterns Theory approach which is supported by the theory of relationship turbulence. The research method used is a qualitative method with data collection techniques in the form of interviews with four husband and wife couples who live in the city of Bandar Lampung, the determination of the informants is obtained through a snowball sampling strategy (multistage method) with expert informants as data confirmation. The results show that all couples have a separate balanced communication pattern (balanced split pattern) during the face of postpartum stress, which is marked by the division of responsibilities in different roles. In a balanced split communication pattern, all informants experience interferences as well as communication supports, and some experience relationship uncertainty, while constructive strategies are used as approaches in conflict management strategies between partners, characterized by open communication and negotiation. Conflicts related to childcare tasks and lack of quality interactions were the findings of this study. Abstrak Periode pasca melahirkan adalah periode transisi yang dialami oleh pasangan suami istri yang membutuhkan upaya penyesuaian dalam hubungan relasi, terlebih saat pihak istri mengalami tekanan/depresi pasca melahirkan selama periode tersebut. Periode pasca melahirkan menimbulkan perubahan kondisi, berupa perubahan peran dan tanggung jawab, yang dapat mempengaruhi hubungan komunikasi di antara pasangan. Penelitian ini berfokus pada pola komunikasi suami-istri dalam tekanan pasca melahirkan dengan metode penelitian kualitatif. Teknik pengambilan data berupa wawancara terhadap empat pasangan suami istri di Bandar Lampung yang didapat dari teknik pengambilan sample snowball sampling, Hasil menunjukkan bahwa seluruh pasangan memiliki pola komunikasi seimbang terpisah selama menghadapi tekanan pasca melahirkan, yang ditandai dengan adanya pembagian tanggung jawab pada peran yang berbeda. Dalam pola komunikasi seimbang terpisah, seluruh informan mengalami hambatan juga dukungan komunikasi, dan sebagian mengalami ketidakpastian hubungan. Sementara, strategi konstruktif digunakan sebagai pendekatan dalam strategi manajemen konflik di antara pasangan, ditandai dengan adanya keterbukaan komunikasi dan negosiasi. Konflik terkait dengan tugas pengasuhan anak dan kurangnya kualitas interaksi menjadi temuan dalam penelitian ini.

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