Numerical Techniques in Electromagnetics is designed to show the reader how to pose, numerically analyze, and solve electromagnetic (EM) problems. It gives them the ability to expand their problem-solving skills using a variety of available numerical methods. Topics covered include fundamental concepts in EM; numerical methods; finite difference methods; variational methods, including moment methods and finite element methods; transmission-line matrix or modeling (TLM); and Monte Carlo methods. The simplicity of presentation of topics throughout the book makes this an ideal text for teaching or self-study by senior undergraduates, graduate students, and practicing engineers.

Numerical Techniques in Electromagnetics, Second Edition

A circular phased array antenna that can generate orbital angular momentum (OAM) radio beams in the 10 GHz band is described. The antenna consists of eight inset-fed patch elements and a microstrip corporate feeding network. A full-wave electromagnetic simulator is used to aid the antenna design and theoretical simulations are confirmed by measurements.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/el.2014.2860

Experimental circular phased array for generating OAM radio beams

The finite-difference time-domain (FDTD) method is arguably the most popular numerical method for the solution of problems in electromagnetics. Although the FDTD method has existed for nearly 30 years, its popularity continues to grow as computing costs continue to decline. Furthermore, extensions and enhancements to the method are continually being published, which further broaden its appeal. Because of the tremendous amount of FDTD-related research activity, tracking the FDTD literature can be a daunting task. We present a selective survey of FDTD publications. This survey presents some of the significant works that made the FDTD method so popular, and tracks its development up to the present-day state-of-the-art in several areas. An "on-line" BibT/sub E/X database, which contains bibliographic information about many FDTD publications, is also presented. >

A selective survey of the finite-difference time-domain literature

An eight-port antenna array operating in 3.5 GHz band (3400–3600 MHz) and 5 GHz band (4800–5100 MHz) for fifth-generation multiple-input multiple-output (MIMO) in mobile handsets is presented. To reserve space for 2G/3G/4G antenna configuration, the eight-antenna array formed by two quad-antenna arrays is printed along the two long frames of the smartphone. Each antenna array unit is formed by a folded monopole and a gap-coupled loop branch, and they are disposed on the upper and bottom sides of the system circuit board, respectively. As the gap between each array unit is only 10 mm, a neutralized line is introduced between the two middle antenna units for reducing the mutual coupling. The measured results have exhibited good impedance matching and isolation. To evaluate the MIMO performance, the envelope correlation coefficient, mean effective gain, and ergodic channel capacity are investigated. Furthermore, the hand phantom effects and display panel effects are also given.

Side-Edge Frame Printed Eight-Port Dual-Band Antenna Array for 5G Smartphone Applications

This article presents a wideband orthogonal-mode dual-antenna pair with a shared radiator for fifth-generation (5G) multiple-input multiple-output (MIMO) metal-rimmed smartphones. The wideband decoupling property of the dual-antenna pair is realized by the combination of the orthogonal monopole/dipole modes in the lower band and the orthogonal slot/open-slot modes in the higher band. With the orthogonal-mode design scheme, the dual-antenna pair shows a wide impedance bandwidth of 3.3–5.0 GHz and a high isolation of more than 21.0 dB across the entire band without using any external decoupling structures. By arranging four such dual-antenna pairs at two side edges of the smartphone, an $8 \times 8$ MIMO system is fulfilled. Both the simulation and measurement results show that the proposed $8 \times 8$ MIMO system could offer an isolation of better than 12.0 dB and an envelope correlation coefficient of lower than 0.11 between all ports. The measured average antenna efficiencies are 74.7% and 57.8% for the two antenna elements of the dual-antenna pair. We portend that the proposed design scheme, with merits of shared radiator, wide bandwidth, and metal rim compatibility, has the potential for the application of future 5G smartphones.

Wideband 5G MIMO Antenna With Integrated Orthogonal-Mode Dual-Antenna Pairs for Metal-Rimmed Smartphones

This communication presents a wideband circularly polarized (CP) 2 × 2 patch array using a sequential-phase feeding network. By combining three operating modes, both axial ratio (AR) and impedance bandwidths are enhanced and wider than those of previous published sequential-fed single-layer patch arrays. These three CP operating modes are tuned and matched by optimizing the truncated corners of patch elements and the sequential-phase feeding network. A prototype of the proposed patch array is built to validate the design experimentally. The measured -10-dB impedance bandwidth is 1.03 GHz (5.20-6.23 GHz), and the measured 3-dB AR bandwidth is 0.7 GHz (5.25-5.95 GHz), or 12.7% corresponding to the center frequency of 5.5 GHz. The measured peak gain is about 12 dBic and the gain variation is less than 3 dB within the AR bandwidth.

A Wideband Sequential-Phase Fed Circularly Polarized Patch Array

In this letter, a novel multiple-input–multiple-output (MIMO) antenna operating at 3500 MHz band is presented for 5G mobile terminals. The proposed antenna includes four blocks. Each block consists of two face-to-face elements with total size of 25 × 3.5 mm2. Rather than excited separately, the two elements are excited simultaneously. Pattern diversity is achieved by using in-phase and out-of-phase signals. A compact two-port feed network is designed to provide the required feed signals. The measured bandwidth for the two ports is 750 MHz (3.06–3.81 GHz) and 340 MHz (3.33–3.67 GHz), which is sufficient to cover the 3400–3600 MHz band. The port isolation is higher than 14 dB in the overlapping bandwidth.

High-Isolated MIMO Antenna Design Based on Pattern Diversity for 5G Mobile Terminals

The behavior of a mobile handset chassis-mode antenna with a metal bezel is analyzed in this paper by utilizing the theory of characteristic modes (TCM). Two eigenmodes, one from the chassis $(\text{0.5}\uplambda\hbox{-}{\text{dipole mode}})$ and the other one from the bezel $(\text{1}\uplambda\hbox{-}{\text{perimeter mode}})$ , are merged by a monopole exciter to broaden the antenna bandwidth below 1 GHz. A new eigenmode from the bezel $(\text{1.5}\uplambda\hbox{-}{\text{perimeter mode}})$ is also exploited to achieve multiple-input multiple-output (MIMO) performance. The characteristics of the antenna are verified with an experimental prototype and measurements. The measured input reflection bandwidths from the two ports are 263 MHz (742–1005 MHz) and 93 MHz (863–956 MHz), respectively. The port isolation is more than 7.4 dB across the whole band of interest. Finally, the monopole exciter, which excites two eigenmodes in the low-frequency band, is modified to provide more resonances in the upper frequency band, providing coverage in the range of 1715–2060 MHz and 2280–2710 MHz.

MIMO Mobile Handset Antenna Merging Characteristic Modes for Increased Bandwidth

In this paper, a compact multiple-input multiple-output (MIMO) antenna is presented for 5G mobile terminals. The antenna consists of four tightly arranged elements and three lumped components. The edge-to-edge distance between adjacent elements is only 1 mm. It is found that adding an inductor at the current minimum location or a capacitor at the current maximum location of two elements can significantly reduce the mutual coupling. Based on high-isolated dual-element structures, a four-element MIMO antenna is experimentally analyzed for 3400–3600 MHz band. The size of the antenna is only $40.8 \times 3$ mm2. The measured −6 dB bandwidth of the antenna is 135 MHz, with port isolation higher than 11.6 dB. In addition, a vertically placed four-element MIMO antenna is designed with a size of $38.2\times3.2$ mm2. No ground clearance is needed between the antenna and the chassis ground.

Tightly Arranged Four-Element MIMO Antennas for 5G Mobile Terminals

This paper gives a feasible and simple solution of generating OAM-carrying radio beams. Eight Vivaldi antenna elements connect sequentially and fold into a hollow cylinder. The circular Vivaldi antenna array is fed with unit amplitude but with a successive phase difference from element to element. By changing the phase difference at the steps of 0, ±45°, ±90°, ±135°, and 180°, the OAM radio beam can be generated with mode numbers 0, ±1, ±2, ±3, and 4. Simulations show that the OAM states of ±2 and ±3 are the same as the traditional states, while the OAM states of 0, ±1, and 4 differ at the boresight. This phenomenon can be explained by the radiation pattern difference between Vivaldi antenna and tripole antenna. A solution of distinguishing OAM states is also proposed. The mode number of OAM can be distinguished with only 2 receivers.

/pdf/generation-of-oam-radio-waves-using-circular-vivaldi-antenna-1tgzsknsrp.pdf

Changjiang Deng

Papers

A Wideband Sequential-Phase Fed Circularly Polarized Patch Array

High-Isolated MIMO Antenna Design Based on Pattern Diversity for 5G Mobile Terminals

MIMO Mobile Handset Antenna Merging Characteristic Modes for Increased Bandwidth

Tightly Arranged Four-Element MIMO Antennas for 5G Mobile Terminals

Generation of OAM Radio Waves Using Circular Vivaldi Antenna Array