scholarly journals A Rigorous Method for Synthesis of Offset Shaped Reflector Antennas

2006 ◽  
Vol 2 (1-2) ◽  
pp. 29-49 ◽  
Author(s):  
Vladimir I. Oliker
Keyword(s):  
High Efficiency ◽  
Near Field ◽  
Nonlinear Partial Differential Equations ◽  
Reflector Antenna ◽  
Antenna System ◽  
New Method ◽  
Reflector Antennas ◽  
Strongly Nonlinear ◽  
The Subject ◽  
Over 40 Years

In this paper the problem of synthesis of offset shaped single reflector antenna is considered. This problem has to be solved when a reflector antenna system is required to control the field amplitude and/or phase on the far-field or on the output aperture in the near-field. Achieving high efficiency is a very important objective of the design and shaped reflector antennas are used for that purpose.The equations of the problem are strongly nonlinear partial differential equations which can not be analyzed by standard techniques. Though the problem has been the subject of study by many authors for over 40 years, up until recently, there were no rigorous theoretical results resolving completely the questions of existence and uniqueness. With few exceptions, authors have attacked the problem with heuristic numerical procedures, and, depending on the specific formulation, obtained different results not always in agreement with each other.In this paper a new method for solving the single reflector problem is presented. The new method allows a complete and mathematically rigorous investigation of this problem. Furthermore, the proposed method lends itself to a numerical implementation and we present here several examples.

scholarly journals Ka-Band Lightweight High-Efficiency Wideband 3D Printed Reflector Antenna

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yu Zhai ◽  
Ding Xu ◽  
Yan Zhang
Keyword(s):  
High Efficiency ◽  
Near Field ◽  
Side Lobe ◽  
High Gain ◽  
Reflector Antenna ◽  
Field Analysis ◽  
Side Lobe Level ◽  
Ka Band ◽  
3D Printed ◽  
Reflecting Surface

This paper presents a lightweight, cost-efficient, wideband, and high-gain 3D printed parabolic reflector antenna in the Ka-band. A 10 λ reflector is printed with polylactic acid- (PLA-) based material that is a biodegradable type of plastic, preferred in 3D printing. The reflecting surface is made up of multiple stacked layers of copper tape, thick enough to function as a reflecting surface (which is found 4 mm). A conical horn is used for the incident field. A center-fed method has been used to converge the energy in the broadside direction. The proposed antenna results measured a gain of 27.8 dBi, a side lobe level (SLL) of −22 dB, and a maximum of 61.2% aperture efficiency (at 30 GHz). A near-field analysis in terms of amplitude and phase has also been presented which authenticates the accurate spherical to planar wavefront transformation in the scattered field.

CROSS-POLARIZATION OF DUAL-REFLECTOR ANTENNA

2021 ◽  
Author(s):  
А.П. ВОРОНЦОВ ◽  
К.М. ВОЛГАТКИН ◽  
С.В. ЕРМОЛАЕВ ◽  
И.Н. ПРИЩЕПА
Keyword(s):  
Polarization Vector ◽  
Reflector Antenna ◽  
Antenna System ◽  
Sufficient Condition ◽  
Cross Polarization ◽  
Necessary And Sufficient Condition ◽  
Reflector Antennas ◽  
Single Polarization ◽  
Dual Reflector Antenna ◽  
Necessary And Sufficient

Рассмотрен вопрос расчета кроссполяризации двухзеркальных антенн с вынесенным облучателем и использованием комплексных координат. Приведено необходимое и достаточное условие для нулевого уровня кроссполяризации в апертуре рефлектора. Дан пример расчета тангенса угла наклона единичного вектора поляризации в апертуре рефлектора двухзеркальной антенной системы типа Кассегрена. The problem of calculating the cross-polarization of dual-reflector antennas with offset feed using complex coordinates is considered. A necessary and sufficient condition for the zero level of cross-polarization in the reflector aperture is given. The example of calculating the tangent of the angle of slope of a single polarization vector in the aperture of a reflector of a Cassegrain-type dual-reflector antenna system is presented.

scholarly journals Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rohith Mittapally ◽  
Byungjun Lee ◽  
Linxiao Zhu ◽  
Amin Reihani ◽  
Ju Won Lim ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Efficiency ◽  
Near Field ◽  
Electrical Power ◽  
Photovoltaic Cells ◽  
High Power Density ◽  
Pv Cell ◽  
Electrical Power Output ◽  
Power Densities

AbstractThermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m2 at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K–1270 K) and gap sizes (70 nm–7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

scholarly journals Innovative Method for Calculating the Break-Even for Multi-Assortment Production

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4213
Author(s):  
Dariusz Fuksa
Keyword(s):  
Coal Mines ◽  
New Method ◽  
Hard Coal ◽  
Customer Demand ◽  
Innovative Method ◽  
The Subject ◽  
Economic Health ◽  
Production Plans ◽  
A Company ◽  
A Current

The subject of the article is a new method that I have developed for calculating a multi-asset break-even for multi-assortment production, extended by a percentage threshold and a current sales ratio (which was missing in previously published methods). The percentage threshold provides unambiguous information about the economic health of a company. As a result, it became possible to use it in practice to evaluate the activities of economic entities (mines) and to perform modelling and optimisation of production plans based on different variants of customer demand scenarios. The publication addresses the complexity of the problem of determining the break-even in multi-assortment production. Moreover, it discusses the practical limitations of previous methods and demonstrates the usefulness of the proposed method on the example of hard coal mines.

scholarly journals Design of Multi Standard Near Field Communication Outphasing Transmitter with Modulation Wave Shaping

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 188
Author(s):  
Žiga Korošak ◽  
Nejc Suhadolnik ◽  
Anton Pleteršek
Keyword(s):  
Radio Frequency Identification ◽  
High Efficiency ◽  
Near Field ◽  
Cmos Technology ◽  
Near Field Communication ◽  
Differential Delay ◽  
Fully Differential ◽  
Delay Locked Loop ◽  
Modulation Wave ◽  
The Individual

The aim of this work is to tackle the problem of modulation wave shaping in the field of near field communication (NFC) radio frequency identification (RFID). For this purpose, a high-efficiency transmitter circuit was developed to comply with the strict requirements of the newest EMVCo and NFC Forum specifications for pulse shapes. The proposed circuit uses an outphasing modulator that is based on a digital-to-time converter (DTC). The DTC based outphasing modulator supports amplitude shift keying (ASK) modulation, operates at four times the 13.56 MHz carrier frequency and is made fully differential in order to remove the parasitic phase modulation components. The accompanying transmitter logic includes lookup tables with programmable modulation pulse wave shapes. The modulator solution uses a 64-cell tapped current controlled fully differential delay locked loop (DLL), which produces a 360° delay at 54.24 MHz, and a glitch-free multiplexor to select the individual taps. The outphased output from the modulator is mixed to create an RF pulse width modulated (PWM) output, which drives the antenna. Additionally, this implementation is fully compatible with D-class amplifiers enabling high efficiency. A test circuit of the proposed differential multi-standard reader’s transmitter was simulated in 40 nm CMOS technology. Stricter pulse shape requirements were easily satisfied, while achieving an output linearity of 0.2 bits and maximum power consumption under 7.5 mW.

scholarly journals Construction of new solitary wave solutions of generalized Zakharov-Kuznetsov-Benjamin-Bona-Mahony and simplified modified form of Camassa-Holm equations

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 896-909 ◽  
Author(s):  
Dianchen Lu ◽  
Aly R. Seadawy ◽  
Mujahid Iqbal
Keyword(s):  
Solitary Wave ◽  
Nonlinear Partial Differential Equations ◽  
Research Work ◽  
Traveling Wave Solutions ◽  
Elliptic Functions ◽  
Mapping Method ◽  
New Method ◽  
Auxiliary Equation ◽  
Solitary Wave Solutions ◽  
Wave Solutions

AbstractIn this research work, for the first time we introduced and described the new method, which is modified extended auxiliary equation mapping method. We investigated the new exact traveling and families of solitary wave solutions of two well-known nonlinear evaluation equations, which are generalized Zakharov-Kuznetsov-Benjamin-Bona-Mahony and simplified modified forms of Camassa-Holm equations. We used a new technique and we successfully obtained the new families of solitary wave solutions. As a result, these new solutions are obtained in the form of elliptic functions, trigonometric functions, kink and antikink solitons, bright and dark solitons, periodic solitary wave and traveling wave solutions. These new solutions show the power and fruitfulness of this new method. We can solve other nonlinear partial differential equations with the use of this method.

A new method to calculate near-field radiation excited by heterogeneous fault rupture

2007 ◽  
Vol 20 (6) ◽  
pp. 597-604
Author(s):  
Xue-feng Shang ◽  
Qi-ming Liu ◽  
Hai-ming Zhang ◽  
Xiao-fei Chen
Keyword(s):  
Near Field ◽  
New Method ◽  
Fault Rupture ◽  
Field Radiation
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