A Compact and Low Profile Loop Antenna with Six Resonant Modes for LTE Smart phone

In this paper, a novel six-mode loop antenna covering 660-1100 MHz, 1710-3020 MHz, 3370-3900 MHz, and 5150-5850 MHz has been proposed for the application of Long Term Evolution (LTE) including the coming LTE in unlicensed spectrum (LTE-U) and LTE-Licensed Assisted Access (LTE-LAA). Loop antennas offer better user experience than conventional Planar Inverted-F Antennas (PIFA), Inverted-F Antennas (IFA), and monopole antennas because of their unique balanced modes (1?, 2?, …). However, the bandwidth of loop antennas is usually narrower than that of PIFA/IFA and monopole antennas due to these balanced modes. To overcome this problem, a novel monopole/dipole parasitic element, which operates at an unbalanced monopole-like 0.25? mode and a balanced dipole-like 0.5? mode, is first proposed for loop antennas to cover more frequency bands. Benefiting from the balanced mode, the proposed parasitic element is promising to provide better user experience than conventional parasitic elements. To the authors’ knowledge, the balanced mode for a parasitic element is reported for the first time. The proposed antenna is able to provide excellent user experience while solving the problem of limited bandwidth in loop antennas. To validate the concept, one prototype antenna with the size of 75×10×5 mm3 is designed, fabricated and measured. Both simulations and experimental results are presented and discussed. Good performance is achieved

Wideband Back-Cover Antenna Design Using Dual Characteristic Modes With High Isolation for 5G MIMO Smartphone

© 2022 IEEE - All rights reserved. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1109/TAP.2022.3145456A novel method of designing a wideband high isolated dual-antenna pair using dual characteristic modes (CMs)is presented for fifth-generation (5G) multiple-input multiple output (MIMO) smartphone applications. A set of orthogonal CMs resonating from the square-loop slot is first introduced and works for the lower band. Then, another set of orthogonal CMs resonating from the edge branches is introduced with a shared compact radiator and works for the higher band. In combination with two sets of degenerated CMs and a capacitive coupling feeding structure, the proposed dual-antenna pair achieves abroad impedance bandwidth and high isolation without the need for any external decoupling structures. Based on this dual-antenna pair, an 8×8 MIMO array is developed and integrated into the back cover of a smartphone, which realizes zero ground clearance on the system circuit board. To verify the design concept, prototypes of the antenna pair and MIMO array were fabricated and measured. It shows that experimental results agree well with the simulation results. More importantly, the presented 8×8 MIMO array has high isolation of more than 20 dBis achieved across the operating band of 3.3-3.8 GHz.Peer reviewedFinal Accepted Versio

Dual-Band Ten-Element MIMO Array Based on Dual-Mode IFAs for 5G Terminal Applications

A dual-band ten-element MIMO array based on dual-mode inverted-F antennas (IFAs) for 5G terminal applications is presented in this paper. The proposed dual-mode IFA is composed of two radiators, which are etched on the outer and inner surfaces of the side-edge frame. The outer part of the antenna generates the low-order mode at 3.5 GHz, while the inner part radiates another one-quarter-wavelength mode at 4.9 GHz. In this way, the IFA can achieve dual-band operation within a compact size of 10.6 × 5.3 × 0.8 mm 3 . Based on the proposed antenna, a dual-band ten-element multiple-input and multiple-output (MIMO) array is developed for 5G terminal applications. By combining neutralization line structures with decoupling branches, the isolations between the elements are improved. To validate the design concept, a prototype of the ten-element MIMO array is designed, fabricated, and measured. The experimental results show that the proposed antenna can cover the 3.3-3.6 GHz and 4.8-5.0 GHz bands with good isolation and high efficiency. Furthermore, the envelope correlation coefficient (ECC), and channel capacity are also calculated to verify the MIMO performances for 5G sub-6GHz applications

Dual-Band Eight-Element MIMO Array Using Multi-Slot Decoupling Technique for 5G Terminals

This paper presents a dual-band eight-element multiple-input multiple-output (MIMO) array using a multi-slot decoupling technique for the fifth generation (5G) mobile communication. By employing a compact dual-loop antenna element, the proposed array obtains two broad bandwidths of 12.2% and 15.4% for sub-6GHz operation. To reduce the mutual coupling between antenna elements, a novel dual-band decoupling method is proposed by employing a multi-slot structure. The proposed MIMO array achieves 15.5-dB and 19.0-dB isolations across the two operating bands. Furthermore, three decoupling modes generated by different bent slots can be independently tuned. Zero ground clearance is also realized by the coplanar arrangement of the antenna elements and decoupling structures. The proposed MIMO array was simulated, fabricated, and measured. Experimental results agree well with the simulations, showing that the dual-band MIMO array has good impedance matching, high isolation, and high efficiency. In addition, the envelope correlation coefficient and channel capacity are calculated and analyzed to validate the MIMO performance of the 5G terminal array. Such a dual-band high-isolation eight-element MIMO array with zero ground clearance is a promising candidate for 5G or future mobile applications

A Novel Low-Cost H-plane Decoupling Technique for Two Closely Placed Patch Antennas Using Electric and Magnetic Coupling Cancellation

This paper presents a novel low-cost method for decoupling two closely-placed H -plane arranged patch antennas. This new electric and magnetic coupling cancellation (EMCC) decoupling concept is simple yet highly effective, requiring no additional decoupling structures or complicated manufacturing processes. According to the proposed concept, the mutual coupling between two patches can be suppressed by controlling the weight of the electric ( E ) and magnetic ( H ) coupling between them. When the E -coupling and H -coupling are comparable, a deep null will arise on the mutual coupling curve, resulting in high isolation in the band of interest. To validate the approach, two prototypes for both 2-element and 4-element multi-input multi-output (MIMO) arrays, are designed, fabricated, and measured. The experimental results agree well with the simulations, highlighting the advantages of this method, including low cost, high isolation, and simple antenna structures

A Cascaded Resonator Decoupling Network for Two Filtering Antennas

In this paper, a novel method for the decoupling between two filtering antennas is presented. The mutual coupling between two filtering antennas is investigated and a coupled-resonator decoupling network (DN) is developed. This coupled-resonator DN is co-designed with the coupled filtering antennas with little effect on the original filtering responses. By connecting this network to the coupled antennas in parallel, the mutual coupling between two 2 nd order filtering antennas can be suppressed dramatically. A step-by-step realization of the DN is provided. To verify the concept, a prototype using the proposed DN was fabricated and measured. Full-wave simulations and measurements indicate that this coupled-resonator DN can enhance the isolation between two filtering antennas up to 30 dB without significantly affecting the filtering performance of each antenna, at a cost of 1.15 dB efficiency drop

Mutual Coupling Suppression Between Two Closely Placed Patch Antennas Using Higher-Order Modes

this article presents a novel method for decoupling two patch antennas. Instead of using the TM 10 mode of a conventional patch, TM 20 mode is utilized as the operation mode of the antenna. By loading stubs at the radiating edge of the patch, the resonance frequency of the TM 20 mode is moved down to the same band as the original TM 10 mode. Then, the mutual coupling between two such patch antennas is suppressed simply by physical placement, even when they are placed extremely close to each other. Without using any extra decoupling elements, isolation is improved by up to 20 dB using this method. Furthermore, this method can also be applied to multielement multi-input -multi-output (MIMO) array and dual-antenna system with different operating bands. The proposed method is verified with three different application scenarios, including a two-element MIMO array, a two-antenna system with adjacent operating bands, and a four-element MIMO array. Reasonable agreements between simulated and measured results can be observed, showing the advantages of simple structure, low cost, high isolation, and good radiation performance

Loss of Asxl1 Alters Self-Renewal and Cell Fate of Bone Marrow Stromal Cell, Leading to Bohring-Opitz-like Syndrome in Mice

De novo ASXL1 mutations are found in patients with Bohring-Opitz syndrome, a disease with severe developmental defects and early childhood mortality. The underlying pathologic mechanisms remain largely unknown. Using Asxl1-targeted murine models, we found that Asxl1 global loss as well as conditional deletion in osteoblasts and their progenitors led to significant bone loss and a markedly decreased number of bone marrow stromal cells (BMSCs) compared with wild-type littermates. Asxl1(-/-) BMSCs displayed impaired self-renewal and skewed differentiation, away from osteoblasts and favoring adipocytes. RNA-sequencing analysis revealed altered expression of genes involved in cell proliferation, skeletal development, and morphogenesis. Furthermore, gene set enrichment analysis showed decreased expression of stem cell self-renewal gene signature, suggesting a role of Asxl1 in regulating the stemness of BMSCs. Importantly, re-introduction of Asxl1 normalized NANOG and OCT4 expression and restored the self-renewal capacity of Asxl1(-/-) BMSCs. Our study unveils a pivotal role of ASXL1 in the maintenance of BMSC functions and skeletal development

Mudskipper genomes provide insights into the terrestrial adaptation of amphibious fishes

Mudskippers are amphibious fishes that have developed morphological and physiological adaptations to match their unique lifestyles. Here we perform whole-genome sequencing of four representative mudskippers to elucidate the molecular mechanisms underlying these adaptations. We discover an expansion of innate immune system genes in the mudskippers that may provide defence against terrestrial pathogens. Several genes of the ammonia excretion pathway in the gills have experienced positive selection, suggesting their important roles in mudskippers’ tolerance to environmental ammonia. Some vision-related genes are differentially lost or mutated, illustrating genomic changes associated with aerial vision. Transcriptomic analyses of mudskippers exposed to air highlight regulatory pathways that are up- or down-regulated in response to hypoxia. The present study provides a valuable resource for understanding the molecular mechanisms underlying water-to-land transition of vertebrates