Multi-objective optimization design of S-shaped inlet with internal bump

The parallel higher-order method of moments (HoMoM) with a GPU accelerated out-of-core LU solver is presented for analysis of radiation characteristics of a 1000-element antenna array over a full-size airplane. A parallel framework involving MPI and CUDA is adopted to ensure that the procedures run on a hybrid CPU/GPU cluster. An efficient two-level out-of-core scheme is designed to break the bottleneck of both GPU memory and physical memory when solving electrically large and complex problems. To hide communication time between CPU and GPU, asynchronous communications are chosen to enable overlapping between communication and computation. For large problems that cannot fit in GPU memory or physical memory, the two-level out-of-core LU solver is able to achieve a speedup of about 1.6x over the traditional out-of-core LU solver based on a highly optimized math library.

/pdf/an-efficient-gpu-based-out-of-core-lu-solver-of-parallel-2qwsvfuxwb.pdf

An Efficient GPU-Based Out-of-Core LU Solver of Parallel Higher-Order Method of Moments for Solving Airborne Array Problems

The performance of the parallel out-of-core Higher-order Method of Moments (HoMoM) is analysed in this paper. The I/O to hard disks significantly affects the performance of the out-of-core algorithm. In order to reduce the I/O time, solid state drives (SSD) with high read and write speeds are utilized. The size of the in-core buffer allocated to each process, IASIZE, is tuned to achieve the optimum performance of the out-of-core algorithm. Numerical results show that the out-of-core algorithm using SSD exhibits better performance than that using SAS hard drives. As a challenging application, a slot array with 2068 elements is analysed using this method.

SSD Accelerated Parallel Out-of-Core Higher-Order Method of Moments and Its Large Applications

Quadrifilar helix antennas (QHA) are widely used in various applications. QHA performance strongly depends on its feed network parameters. A proper network should equally divide power from input port between output ports and provide quadrature phases (0, 90, 180 and 270°) within antenna frequency band. Two microstrip feed networks are presented in the report. Both networks are based on Wilkinson power splitter and have similar shape — a 39 mm diameter circle. First one is designed for a small QHA with a low input impedance (12Ohm). It consists of planar two-port impedance-transforming Wilkinson splitters. Each splitter reduces output impedance by a factor of 2. Three splitters are cascaded to form a 4-port network. Proper phasing is achieved by means of microstrip delay lines. To equalize output signal amplitudes the splitters have been made non-symmetrical. Bandwidth of the network is much higher than required for a narrow-band (2–3%) QHA. Insertion loss is 1 dB higher than that of ideal network. Relatively high return loss (− 16 dB) results from interference with second stage dividers. Another drawback is high reflection from via holes which inevitably act as π-type filters. The second feed network is designed for a larger QHA with input impedance 28 Ohms. It is an impedance-transforming 4-port Wilkinson divider. Like in the first design, microstrip delay lines provide proper phasing. Network bandwidth and transmission losses are similar to the first one, but has the advantage of lower return losses due to absence of interference with second stage splitter. Simpler design allowed placing almost everything in the top plane of PCB except for splitter resistors. In a matched case, no current flows through these resistors, so the negative effects of via holes are negligible. Reducing complexity and demands for impedance transformation improved performance of this network compared to the first one. Return loss is lower than −25 dB within antenna operation range. Insertion loss is 0.7 dB higher than in case of ideal network and slightly lower than return loss of the first network.

Compact microstrip feed networks for low-impedance quadrifillar helix antennas

Bentuk dasar antena heliks quadrifilar dikembangkan oleh C. C. Kilgus dari Laboratorium Fisika Terapan, Universitas Johns Hopkins, USA. Antena ini memiliki beamwidth yang lebar sampai 2400 dengan pola radiasi berbentuk jantung, berpolarisasi sirkular dan tidak memerlukan reflektor. Antena heliks quadrifilar memiliki rasio diameter terhadap tingginya 0,66. Artinya antena ini ditempatkan di on-board satelit sebagai pemancar (Tx). Ukuran dari antena ini adalah ½ λ ½ putaran dan termasuk dalam varian putaran kecil. Tujuan dari riset ini adalah membuat prototip antena heliks quadrifilar untuk satelit mikro, dengan frekuensi 2,22 GHz dan selanjutnya diuji dalam skala laboratorium. Dari hasil pengujian laboratorium, besarnya RL adalah -18.55 dB, besarnya VSWR adalah 1,26, besarnya lebar pita adalah 6,04 %, besarnya lebar berkas adalah 1700 dan besarnya penguatan adalah 5,19 dB.

/pdf/pengembangan-antena-heliks-quadrifilar-2-22-ghz-untuk-2reuodjeli.pdf

Pengembangan Antena Heliks Quadrifilar 2,22 GHZ Untuk Satelit Mikro

A parallel version of Method of Moments (MoM) with Higher-Order Basis functions (HOB-MoM) with the Out-of-Core technique (OOC) is proposed to compute the Radar Cross Section (RCS) of an aircraft with engine inlets in this paper. The block-partitioned parallel scheme for the large dense MoM matrix is designed to achieve excellent load balancing and high parallel efficiency. The OOC technology is employed to break through the random access memory (RAM) limitation. Some numerical results demonstrate that the higher-order basis used in this paper is superior to the conventional RWG basis and is suitable to solve various electrically large problems such as the computation of RCS.

http://ap-s.ei.tuat.ac.jp/isapx/2013/pdf/158_2_0.pdf

Accurate evaluation of RCS on the structure of aircraft inlets

The parallel higher-order Method of Moments based on message passing interface (MPI) has been successfully used to analyze the changes in radiation patterns of a microstrip patch array antenna mounted on different positions of an airplane. The block-partitioned scheme for the large dense MoM matrix and a block-cyclic matrix distribution scheme are designed to achieve excellent load balance and high parallel efficiency. Numerical results demonstrate that the rigorous parallel Method of Moments can efficiently and accurately solve large complex electromagnetic problems with composite structures.

/pdf/simulation-of-airborne-antenna-array-layout-problems-using-3cy3hoiexx.pdf

Simulation of Airborne Antenna Array Layout Problems Using Parallel Higher-Order MoM

This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA). The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values are more than 39% and 31.5%, respectively. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.

/pdf/design-of-a-broadband-inverted-conical-quadrifilar-helix-1iye88d26m.pdf

Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

This paper presents a novel hybrid technique for analyzing complex antennas around the coated object, which is termed the iterative vector fields with Physical Optics (PO) A closed box is used to enclose the antenna and then the complex field vector components on the box' surfaces can be obtained using Huygens principle The equivalent electromagnetic currents on Huygens surface are computed by Higher-order Method of Moments (HOB-MoM) and the fields scattered from the coated platform are calculated by PO method Moreover, the parallel technique based on Message Passing Interface (MPI) and Scalable Linear Algebra Package (ScaLAPACK) is employed to accelerate the computation, and good load balance and parallel efficiency are obtained under the proposed parallel scheme Finally, some numerical examples are presented to validate and to show the effectiveness of the proposed method on solving the practical engineering problems

http://ap-s.ei.tuat.ac.jp/isapx/2013/pdf/29_4_0.pdf

Parallel computation of complex antennas around the coated object using hybrid higher-order MoM and PO technique

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Papers

Accurate evaluation of RCS on the structure of aircraft inlets

Simulation of Airborne Antenna Array Layout Problems Using Parallel Higher-Order MoM

Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

Parallel computation of complex antennas around the coated object using hybrid higher-order MoM and PO technique