High-power Radio Research Articles

Efficacy and Safety of High-power Short-duration Radio Frequency Ablation in the Treatment of Atrial Fibrillation: A Meta-analysis of Prospective Study

Background: Radiofrequency ablation is a critical therapeutic method used in the management of atrial fibrillation (AF). This study systematically evaluates the effectiveness and safety of two catheter radio frequency ablation approaches: high-power short-duration (HPSD) and traditional low-power long-duration (LPLD), in treating AF. Methods: Four databases were searched for prospective studies (eight cohort studies and three randomised controlled trials) that evaluated the effect of HPSD treatment on AF recurrence, occurrence rate of complications and procedural time in patients with AF from the establishment of the databases to March 2023. We utilised RevMan 5.20 and Stata 11.0 statistical software to conduct a meta-analysis, and publication bias was assessed using funnel plots and Egger's test. The effect estimates were synthesised as relative risks (RRs) or standardised mean differences (SMDs) along with their corresponding 95% confidence intervals (CIs). Results: A total of 536 relevant studies were retrieved, and 11 prospective studies were collected. The combined value of the estimated effect of HPSD versus LPLD treatment on AF recurrence in patients with AF had an RR of 0.59 (95% CI: 0.45–0.78; p < 0.001), the effects of HPSD versus LPLD treatment on procedural time in patients with AF had an SMD of –1.17 (95% CI: –1.56– –0.77; p < 0.001), and the effect of HPSD versus LPLD treatment on oesophageal thermal injury in patients with AF had an RR of 0.84 (95% CI: 0.22–3.28; p = 0.80). Notably, the estimated combined effects of HPSD and LPLD on other major complications (steam pop) in patients with AF had an RR of 0.57 (95% CI: 0.22–1.47; p = 0.24). Conclusions: HPSD is more effective than traditional LPLD and has a lower AF recurrence rate after surgery. Meanwhile, HPSD treatment can improve surgical efficiency and has a shorter procedural time than LPLD treatment.

Pulsed High-Power Radio Frequency Energy Can Cause Non-Thermal Harmful Effects on the BRAIN.

High-power microwave applications are growing for both military and civil purposes, yet they can induce brain-related risks and raise important public health concerns. High-power sub-millisecond radio frequency energy pulses have been demonstrated to be able to induce neurological and neuropathological changes in the brain while being compliant with current regulatory guidelines' limits, highlighting the necessity of revising them.

Embedded Microfluidic Cooling in Aluminum Nitride HTCC Substrate for High-Power Radio Frequency Chip Array

Abstract Radio frequency (RF) electronics are developing toward high power, high integration, and high-power density, resulting in a continuous increase in heat flux. The traditional high-power RF package, which is usually composed of aluminum nitride (AlN) substrate, aluminum silicon housing shell, and aluminum alloy cold plate, exhibits poor heat dissipation ability and high thickness due to excessive interfaces and a long thermal conduction path. In this paper, aimed at improving heat dissipation ability and reducing the thickness of RF electronics, the microchannel was transferred from the cold plate to the AlN high-temperature co-fired ceramic (HTCC) substrate which plays the role of electrical connection, structural support, and liquid cooling cold plate. The embedded AlN microchannel cooler was firstly designed. Then, a prototype of the AlN substrate with 64 simulated chip arrays and microchannels was fabricated and the thermal performance was evaluated using an experimental setup. Finally, the thermal performances of the proposed and traditional cooler were compared using a CFD simulation. The results indicated that the proposed embedded cooling structure could enhance the heat-flux dissipation ability by 61% and reduce the packaging thickness by 40% compared with the traditional cooling structure.

Prediction of UAV Swarm Defeat With High-Power Radio Frequency Fields

Swarms of unmanned aerial vehicles (UAVs) can be used to disrupt air traffic and can also function as weapons, since they can either be equipped with improvised explosive devices or can be used for collision purposes. Hence, defensive measures against such threats are important from both a civilian as well as a military perspective. This article argues that high-power radio frequency (HPRF) directed energy weapons (DEWs) can provide a suitable defence against swarms of UAVs. Hence, it would be useful to be able to undertake a performance prediction assessment of the proposed HPRF DEW systems. Consequently, two models are introduced for this purpose and a single measure of performance is derived for each. To illustrate the way in which these models can be used for performance prediction, a particular example of an HPRF DEW is investigated, and its utility in terms of UAV swarm defeat is quantified.

A Stimulated Emission Diagnostic Technique for Electron Temperature of the High Power Radio Wave Modified Ionosphere

AbstractWe report observations of stimulated electromagnetic emission (SEE) induced by high power high frequency (HF) radio waves near the third electron gyroharmonic (3) at European Incoherent Scatter Radar (EISCAT). It is discovered that stimulated Brillouin scattering (SBS) spectrum behaves similarly as spectral ion lines of the incoherent scatter radar (ISR) for HF pumping frequency above 3. The SBS spectral width shows correlation with electron to ion temperature ratio Te/Ti. A new inversion method is proposed by incorporating the SBS spectral width within an artificial neural network approach to achieve electron temperature inversion for ionospheric turbulent plasmas. This work provides a potential new technique to diagnose parameters in the modified ionosphere when the ISR is not available.

Simulation of Large-Scale Disturbances of the Near-Earth Plasma Affected by High-Power High-Frequency Radio Waves from the Sura Heating Facility

Simulation of Large-Scale Disturbances of the Near-Earth Plasma Affected by High-Power High-Frequency Radio Waves from the Sura Heating Facility

The Structure and the Characteristics of the Electromagnetic Field Generated by a High-Power Radio Electronic System

The Structure and the Characteristics of the Electromagnetic Field Generated by a High-Power Radio Electronic System

Response of Background Optical Emission to Ionospheric Heating by High-Power Radio Emission

Response of Background Optical Emission to Ionospheric Heating by High-Power Radio Emission

Research of beam matching on RFQ for CADS proton linac

For a high-power Radio Frequency quadrupole (RFQ) accelerator, it is often necessary to design a large acceptance to decrease the beam loss inside the RFQ cavity. This could allow a mismatched beam to transmit to downstream cavities, which causes beam loss along the downstream linac. Finding the matching condition of beam and RFQ is of great significance. The matching point of RFQ can be confirmed by measuring the emittance at the upstream and downstream of RFQ, which takes a long time, so the transmission efficiency scanning method is supposed to find. This paper compares the relationship among emittance, transmission efficiency, and matching point on CADS[Formula: see text] RFQ. The results show that the weighted average point of high transmission efficiency could be regarded as the matching point of RFQ. This conclusion can be widely used in beam commissioning, and the Transmission Efficiency Scanning-matching (TESM) code has been developed on other RFQs.

Simulation of Large-Scale Disturbances of the Near-Earth Plasma Affected by High-Power Short Radio Waves From the Sura Heating Facility

Simulation of Large-Scale Disturbances of the Near-Earth Plasma Affected by High-Power Short Radio Waves From the Sura Heating Facility

An undergraduate laboratory experiment to build and characterize a thermionic triode for use as an audio amplifier

Although largely superseded by transistors for small signal amplification, the thermionic valve (or tube) still finds use in high-fidelity audio amplifiers, in guitar amplifiers and in high-power radio and television transmitters, where their power to size scalability has advantages over solid state devices. In the undergraduate experiments detailed here students construct a triode inside a vacuum chamber, and investigate the effects of different designs on signal gain. The characteristics of their triodes are measured to determine the optimal condition for signal amplification. The triode is then used to amplify an audio signal to determine the frequency response, and they can listen to the results via headphones using an input signal of their choice. This experiment hence introduces students to vacuum technology, to electron beams and to analog electronics.

Dynamic Changes of the Ionospheric Artificial Airglow Region Caused by High-Power Radio Waves Based on a Joint Analysis of Night-Sky Snapshots in the 630 nm Line and Total Electron Content Variation Maps

We describe a method for joint analysis of the night-sky snapshots and total electron content (TEC) variation maps and present a dynamic spatiotemporal configuration of the TEC variation intensity in the ionospheric airglow region in the red line of atomic oxygen (λ = 630 nm) stimulated by high-power radio waves from the Sura facility. The measurements were performed on the 29th of August, 2016. Two-dimensional TEC variation maps were plotted according to a network of 30 GNSS stations located within a radius of 700 km from the Sura heater. It is shown that the region of the maximum brightness of the artificial ionospheric airglow spot is spatially localized in the region of the minimum intensity of TEC variations, while the region of the maximum intensity of TEC variations corresponds to the region of the minimum brightness of the artificial airglow spot. Quantitative estimates for a cavity with reduced electron density in the artificial airglow region, which forms after the Sura pump wave is switched on, vary in the range ΔNe/Ne ≈ 4–9%, where Ne is the electron density and ΔNe is its variation in the cavity. The proposed experimental technique eliminates the limitations associated with the need for a navigation satellite to flyby directly over the main lobe of the Sura antenna pattern, which significantly increases the chances of successful simultaneous measurements of TEC variations and artificial ionospheric airglow in the 630 nm line.

A Compact and Broadband Directional Coupler for High-Power Radio Frequency Applications

In this letter, a compact and broadband directional coupler is proposed for high-power radio frequency applications in the frequency band of 5–150 MHz. The coupler is composed of a suspended semiflexible coaxial cable and a series of equalizers composed of lumped components. Such design exhibits excellent performance in high power handling capacity (~kW), high directivity (~35 dB), low return loss (>20 dB), and flat coupling coefficient (45 ± 1.3 dB).

Implications of high-power electromagnetic (HPEM) environments on electronics

High-Power Electromagnetic (HPEM) environments can be considered to encompass lightning, Nuclear Electromagnetic Pulse (NEMP) and High-Power Radio Frequency (HPRF) phenomena including Directed Energy (DE) and Intentional Electromagnetic Interference (IEMI). HPEM environment definitions are now maturing and are now described in a variety of published standards. Methods to evaluate the effects on electronic systems and an understanding of effects mechanisms are perhaps less mature but this is a vibrant area of research. Due to a variety of factors described in this article protection and resilience of critical infrastructure from HPEM environments is becoming a pressing need.

Cross-Interface Scheduling Toward Energy-Efficient Device-to-Gateway Communications in IoT

Featured with high bandwidth, high reliability, and native IP compatibility, WiFi has been recommended for a wide range of Internet-of-Things (IoT) applications. However, WiFi is inherently energy-hungry and it may impose high energy consumption on not only IoT devices but also gateways. To reduce gateway’s WiFi energy consumption, many energy-efficient solutions for WiFi tethering services can be applied. However, these solutions mainly target the energy optimization of downlink data traffic in WLANs, and they are not suitable for the uplink data traffic of delivering massive IoT data from device to gateway (D2G), which is more common in IoT. When a gateway is powered by batteries, the high energy consumption caused by D2G communications may deplete the gateway quickly and renders the whole system dysfunctional as a result. Toward achieving energy-efficient D2G communications, we propose an innovative Green IoT Gateway (GIG) scheme, which aims at minimizing gateway energy consumption while ensuring the specific delay requirements of devices via cross-interface collaboration. Through utilizing the coexisting low-power ZigBee radios, GIG dynamically schedules the wakeup behaviors of high-power WiFi radios for energy-efficient and delay-bounded D2G communications. GIG has been implemented and evaluated in a prototype system, and the experiment results show that, under the moderate uplink data traffic and delay requirements, the energy consumption of GIG is 38.5% and 12.7% lower than those of a state-of-the-art WiFi tethering scheme and a simple version of the GIG scheme, respectively. Moreover, a great reduction of energy consumption at the device side can also be observed.

Dual-Radio Configuration for Flexible Communication in Flocking Micro/Miniature Aerial Vehicles

This paper presents an overview of a new dual-radio autopilot and ground station platform used in hierarchical, micro aerial vehicle flocks to improve communication flexibility and performance. Flocks of micro/miniature aerial vehicles flying in close proximity are often used in scenarios of hazard detection and tracking. Micro aerial vehicle's small size grants a number of benefits, such as improved maneuverability and reduced cost, but also results in sometimes severe resource constraints. To help alleviate these restrictions, as well as to improve overall communication flexibility, this paper proposes the use of a hierarchical, dual-radio autopilot flock configuration. Interflock communication is facilitated by low-power radios, whereas an elected flock leader relays important communications to a ground station via a long-range, high-power radio. Additionally, the diversity provided by the dual-radio system provides inherent redundancy while improving flock communication adaptability for varying data sizes and transmit distances. An energy efficiency model for this dual-radio configuration is also presented and verified by autonomous, multi-vehicle flight tests.

In vivo comprehensive multiphase NMR.

Traditionally, due to different hardware requirements, nuclear magnetic resonance (NMR) has developed as two separate fields: one dealing with solids, and one with solutions. Comprehensive multiphase (CMP) NMR combines all electronics and hardware (magic angle spinning [MAS], gradients, high power Radio Frequency (RF) handling, lock, susceptibility matching) into a universal probe that permits a comprehensive study of all phases (i.e., liquid, gel-like, semisolid, and solid), in intact samples. When applied in vivo, it provides unique insight into the wide array of bonds in a living system from the most mobile liquids (blood, fluids) through gels (muscle, tissues) to the most rigid (exoskeleton, shell). In this tutorial, the practical aspects of in vivo CMP NMR are discussed including: handling the organisms, rotor preparation, sample spinning, water suppression, editing experiments, and finishes with a brief look at the potential of other heteronuclei (2 H, 15 N, 19 F, 31 P) for in vivo research. The tutorial is aimed as a general resource for researchers interested in developing and applying MAS-based approaches to living organisms. Although the focus here is CMP NMR, many of the approaches can be adapted (or directly applied) using conventional high-resolution magic angle spinning, and in some cases, even standard solid-state NMR probes.

Radiation pattern analyses of circular aperture antenna to generate radio orbital angular momentum

Circular aperture antenna recently has been regarded as a nature source to generate high power radio orbital angular momentum (OAM) in millimeter (mm) wave; however, the radiation pattern was not investigated. Theoretical derivation of radiation pattern of circular aperture OAM antenna is conducted to evaluate the performance. Extensive simulations verify the validity of the theoretical result. Furthermore, performance of such antenna excited by orthogonal TE and TM modes is compared, which shows the potential application for TEg1 mode to create pure OAM g–1 mode in a practical system, providing guidance for generation of twisted radio waves in mm-wave bands.

Design development and testing of high voltage power supply with crowbar protection for IOT based RF amplifier system in VECC

This paper described the detailed design, development and testing of high voltage power supply (−30 kV, 3.2 A) and different power supplies for biasing electrodes of Inductive Output Tube (IOT) based high power Radio Frequency (RF) amplifier. This IOT based RF amplifier is further used for pursuing research and development activity in superconducting RF cavity project at Variable Energy Cyclotron Centre (VECC) Kolkata. The state-of-the-art technology of IOT-based high power RF amplifier is designed, developed, and tested at VECC which is the first of its kind in India. A high voltage power supply rated at negative polarity of 30 kV dc/3.2 A is required for biasing cathode of IOT with crowbar protection circuit. This power supply along with crowbar protection system is designed, developed and tested at VECC for testing the complete setup. The technical difficulties and challenges occured during the design of cathode power supply, its crowbar protection techniques along with other supported power supplies i.e. grid and ion pump power supplies are discussed in this paper.

Diagnostics of the Generation, Decay, and Transport of Artificial Plasma Perturbations by Means of Short Pulses of High-Power Radio Waves

We discuss the techniques of measuring and the possibilities of using short pulses of high-power radio waves for diagnostics of the properties of high- and low-frequency ionospheric plasma turbulence. The results of the experimental studies performed using the Sura heating facility are presented.