다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

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Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

소형 안테나 ( Small Antennas )

The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is mainly driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks, which are expected to bring transformative changes to this premise. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. In particular, the present paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a comprehensive study of the 6G vision and outlining seven of its disruptive technologies, i.e., mmWave communications, terahertz communications, optical wireless communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss the associated requirements, key challenges, and open research problems. These discussions are thereafter used to open up the horizon for future research directions.

A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks

This review aims to cover experimental data on oxidative effects of low-intensity radiofrequency radiation (RFR) in living cells. Analysis of the currently available peer-reviewed scientific litera...

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Oxidative mechanisms of biological activity of low-intensity radiofrequency radiation

In this paper an ultrathin highly transmissive radial graded index metasurface (RGIMS) lens is proposed and a high gain wide beam steerable low profile lens antenna is designed by placing RGIMS lens on the top of microstrip patch antenna radiator operating at 10.10 GHz. The direction and gain control of radiated beam of microwave radiator is achieved by using modulated metasurface having modified double circular ring resonator as fundamental unit cell. The RGIMS lens can continuously steer the radiated beam of microwave radiator by using radial movement of RGIMS lens. A maximum gain enhancement of 10.21 dB with wide beam scanning up to 32° indicating continuous beam scanning in a conical plane of vertex angle 64° is achieved.

Radial Graded Index Metasurface Lens for Beam Steering and Gain Enhancement

A compact triangular monopole antenna fed by a tapered-coplanar waveguide (CPW) is presented. The simulated and measured return loss results are presented. The proposed antenna offers a wide bandwidth from 4.14?9.84 GHz (81%) covering WLAN frequency bands for IEEE 802.11a and HiperLAN2 as is seen from the measured results.

Tapered-CPW Fed Printed Triangular Monopole Antenna

This paper presents a technique of gain enhancement using stacked dielectric slabs atop a microstrip patch antenna for 28-GHz application. A microstrip patch antenna (MPA) is designed at 28-GHz and loaded with eight 15 × 15mm2 dielectric slabs supported by seven 10 × 10mm2 dielectric slabs in the center. This arrangement of dielectric slabs enhances the gain of MPA by 4.1 dB when loaded very close to the antenna without affecting its input reflection coefficient. The prototype antenna is tested for radiation performance and its observed that the measured and simulated results are in good agreement.

Gain Enhancement of a Millimeter Wave Antenna using Stacked Dielectric-Slabs Superstrate

Abstract This paper proposes a wide band and multiband frequency reconfigurable antenna that can operate in the UWB, GSM, GPS, 4G LTE, WLAN, and WiMAX bands. The antenna is made up of a trapezoidal-shaped monopole radiator, which was inspired by a rectangular monopole antenna. The ground plane is modified by embedding T and L-shaped slots to notch the desired operating frequency. The proposed antenna can switch to six different frequencies using RF PIN diodes, making it suitable for modern wireless applications. A multilayer frequency selective surface (FSS) reflector is presented to improve the gain of the proposed reconfigurable antenna. The low-profile design achieved a significant increase in gain while retaining the UWB antenna's excellent impedance bandwidth. Because of the use of the FSS reflector, the antenna's average peak gain has increased from 6 to 10.4 dBi. The proposed antenna has a wide switching capability, which validates its unique feasibility for high-speed multiple Internet of Things applications via a common embedded platform under various applications.

High gain wideband and multi-band on-demand reconfigurable antenna for modern wireless application

In this paper, a compact microstripline based phase shifter has been proposed. It uses a reconfigurable defected microstripline structure (RDMS) which allows it to be compact. RDMS is made by etching a slot in the microstripline and loading it with capacitor and pin diodes. “ON” and “OFF” states of pin diodes provides phase shift due to different current paths. The results demonstrate 40 % reduction in length of the phase shifter as compared to previous such work [1]. The phase shifter provides a phase shift of 15 degrees at 2.4 Ghz. Subsequently, a four element phased array antenna has been fabricated using eight such phase shifters to steer the beam from −8 to 8 degrees in the H plane and provide a gain of 7.9 dBi. Further, better fabrication techniques promise lesser insertion loss and a better gain leading to practical applications.

Mahesh P. Abegaonkar

Papers

Radial Graded Index Metasurface Lens for Beam Steering and Gain Enhancement

Tapered-CPW Fed Printed Triangular Monopole Antenna

Gain Enhancement of a Millimeter Wave Antenna using Stacked Dielectric-Slabs Superstrate

High gain wideband and multi-band on-demand reconfigurable antenna for modern wireless application

Compact microstrip phase shifter for beam steering antenna