A Multilevel Bottom-Up Optimization Methodology for the Automated Synthesis of RF Systems

Within an increasingly connected world, the exponential growth in the deployment of Internet of Things (IoT) applications presents a significant challenge in power and data transfer optimisation. Currently, the maximization of Radio Frequency (RF) system power gain depends on the design of efficient, commercial chips, and on the integration of these chips by using complex RF simulations to verify bespoke configurations. However, even if a standard 50Ω transmitter’s chip has an efficiency of 90%, the overall power efficiency of the RF system can be reduced by 10% if coupled with a standard antenna of 72Ω. Hence, it is necessary for scalable IoT networks to have optimal RF system design for every transceiver: for example, impedance mismatching between a transmitter’s antenna and chip leads to a significant reduction of the corresponding RF system’s overall power efficiency. This work presents a versatile design framework, based on well-known theoretical methods (i.e., transducer gain, power wave approach, transmission line theory), for the optimal design in terms of power delivered to a load of a typical RF system, which consists of an antenna, a matching network, a load (e.g., integrated circuit) and transmission lines which connect all these parts. The aim of this design framework is not only to reduce the computational effort needed for the design and prototyping of power efficient RF systems, but also to increase the accuracy of the analysis, based on the explanatory analysis within our design framework. Simulated and measured results verify the accuracy of this proposed design framework over a 0–4 GHz spectrum. Finally, a case study based on the design of an RF system for Bluetooth applications demonstrates the benefits of this RF design framework.

Validation of a radio frequency identification system for monitoring the feeding patterns of feedlot cattle

Active harmonic EU cavity: Commissioning and operation with beam

During the remainder of the 1980's and early 1990's, many technology improvements will be made to achieve high data rate satellite-to-satellite communications. Programs such as the Strategic Defense Initiative Organization's SDS (Strategic Defense System) have projected architecture requirements for data transfer rates ranging from hundreds of kilobits per second to hundreds of megabits per second on satellite crosslinks. The advanced technology required to realize these rates is being investigated even now, but a general solution for the communications problem, defined in part by unique operating environ-ments ranging from benign to highly perturbed, is not possible. This paper focuses on one aspect of the overall satellite communications problem. It begins by briefly comparing radio frequency (RF) with direct detection laser communications (lasercom) for application to high data rate SDS low and medium earth orbit crosslinks. This comparison is based on near term technology suitable for early deployment in the SDS. The RF system is a millimeter-wave system operating in the 60 GHz region of the electromagnetic spectrum. The Lasercom system is considered to operate in the near infrared, from 0.8 to 1.1 micrometers. The trades consider operation in benign as well as the very stressing environments postulated for the Strategic Defense System which includes low and high altitude nuclear bursts as well as the threat of spaced based jamming sources and directed energy weapons. Results of the trades are presented to show the advantages and disadvantages of each type of system. The advantages and disadvantages of the RF and Lasercom systems are of sufficient magnitude to consider combining the best features of each to create a truly new communication system with capabilities far exceeding those of either system. For example, maximum survivabilty results from carrying both systems (RF & Lasercom) on the satellite. However, this approach is costly in terms of weight, power, and real estate. A better approach would be to carry the capabilities of both sys-tems. Such an approach is proposed in this paper. The combination of systems, termed the Dual Mode Communications System (DMCS), is the principal thrust of the remainder of the paper.

Low-level radio-frequency system upgrade for the IMP Heavy Ion Reach Facility in Lanzhou (HIRFL)

Laser communication (lasercom) can enable more efficient links across larger distances compared with radio frequency (RF) systems. However, lasercom systems are typically point-to-point connections that would have difficulty interacting with several concurrently active spatially diverse users, where RF systems can more easily support such scenarios. Lasercom pointing, acquisition and tracking (PAT) systems have traditionally relied on mechanical beam steering devices, such as fast steering mirrors (FSMs) or gimbals, both of which are subject to potential mechanical failure. In this work we investigate an alternative steering solution using liquid lenses. Liquid lenses are tunable lenses that can non-mechanically alter focal length based on an applied voltage or current. A series of liquid lenses, one on-axis to control beam divergence, and one each offset in the x and y-axes to steer, could be used to achieve laser pointing control. Currently available commercial off the shelf (COTS) liquid lenses are based on electrowetting (manufactured by Corning [1]) or pressure-driven (manufactured by Optotune [2]) operation. In this work, we analyze the suitability of both types of liquid lenses for use in a space-based multiple access lasercom terminal. Early liquid lens technology first surfaced in 1995 with the control of the shape of an oil droplet through electrowetting [3]. The technology then started to become commercially available with the founding of Varioptic in 2002. However, there is limited data on liquid lens survivability and operation in a space-like environment. Through vacuum testing, we have found that electrowetting-based liquid lenses not only survive, but continue to operate nominally in a very low-pressure environment. The pressure-driven liquid lenses appeared to have issues initially in vacuum testing, with gas bubbles forming in the lens aperture during pump-down. However, after extended exposure to vacuum of approximately two weeks, the gas bubbles diffuse through the lens membrane, and the lenses operate in vacuum. Steering transfer functions were developed both in ambient and in vacuum conditions for both lens types, and in each case, the differences between the two curves were largely negligible. The electrowetting lenses provide a steering range of 2.7°, both in and out of vacuum, with an approximate slope of 0.046°/V. In testing the Optotune lenses, the steering was limited by the camera detector size, but for a range of −92 mA to 144 mA on the steering lens, the lenses provided for approximately 8.6° of steering with a slope of 0.0367°/V. These steering ranges can be extended to near hemispherical coverage with the addition of a diffuser and wide-angle fisheye lens [4]. Maximum hysteresis error, the difference in steering angle response when increasing lens voltage or current as opposed to decreasing lens voltage or current, was identified at 0.02° for the Corning lenses and 0.05° for the Optotune lenses. A Zemax beam quality analysis was conducted to see how transmit gain would be affected by refraction through the liquid lenses. Through this analysis, the worst-case link penalties were determined to be −0.5 dB for the Corning lenses at _0.8° steering and −0.4 dB for the Optotune lenses at _1.0° steering. Thus, we see that liquid lenses are likely good candidates for space applications and may perform well in nonmechanical beam steering. We discuss next steps in environmental testing as well as optical layout and control approaches for using liquid lenses in PAT systems for a nanosatellite based optical antenna.

As the demand for faster, more efficient, and durable electronic devices surges in the age of 5G, electric vehicles, and quantum technologies, researchers are turning to unconventional materials to push the boundaries of what is possible. Among these materials, diamond, long admired for its unmatched thermal conductivity, extreme hardness, and wide bandgap, has emerged as a game-changing contender. When combined with advanced heterojunction architectures, diamond-based heterojunction devices offer a groundbreaking platform that surpasses the limitations of traditional semiconductors like silicon, GaN, and SiC. With potential applications spanning from ultra-fast power electronics to next-generation quantum computing and high-frequency radio frequency (RF) systems, diamond heterojunction devices hold the key to revolutionizing electronics in ways previously unimaginable. This review delves into the remarkable advancements in diamond-based heterojunction devices, highlighting their applications in power electronics, RF systems, quantum technologies, and extreme-environment sensors. Finally, we summarize the current challenges facing diamond heterojunctions and provide an outlook on their transformative potential across the future landscape of high-performance electronics.

The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and are frequently used simultaneously, leading to combined exposures for which almost no exposure evaluation exists. The aim and novelty of this study is to close this gap of knowledge by developing new methods to rapidly evaluate the SAR induced by RF systems in such scenarios at frequencies from 50MHz to 5.5GHz. To this aim, analytical methods for SAR estimation in several usage scenarios were derived through a large-scale numerical study. These include subject-specific characteristics, properties of the RF systems and provide an estimation of the SAR in the whole body, tissues and organs, and different brain regions.

Radiofrequency Thawing of Frozen Minced Fish Based on the Dielectric Response Mechanism

The issue of improving the efficiency of radiocommunication systems and radiocommunication complexes in a complex radio-electronic environment is a prime scientific problem, which attracts attention of a large number of leading scientists. In this article, the author carried out research aimed at increasing the structural secrecy in radio-frequency communication systems with orthogonal frequency multiplexing using timer signal constructions, due to the development of a method of increasing the secrecy in radio-frequency systems with orthogonal frequency muxification due to the use of timer signal structures. In the course of the research carried out by the author, the basic provisions of the theory of communication, the theory of impedance protection, the theory of complex technical systems, the theory of antagonistic systems, the theory of noise immunity coding, the theory of chaotic processes, the theory of orthogonal systems, the theory of radio frequency planning and the theory of timer signal structures. The difference in the proposed methodology from the known, which determines its novelty are: the use of timer signal structures, in contrast to the traditional position signaling structures, it can increase the structural secrecy of signals with orthogonal frequency multiplexing; the use of expanding sequences of different types and with different autocorrelation properties allows for the operational adaptation of parameters of systems and radio communication equipment with orthogonal frequency multiplexing to the effect of destabilizing factors aimed at disclosing the properties of systems and radio communication equipment for electronic intelligence; application of the mechanisms of frequency adaptation to the effect of intentional obstacles allows you to determine the areas of the frequency range struck by them and conduct the intellectual planning of using the radio frequency resources by radio communication systems with orthogonal frequency multiplexing.

Considerations in design of commercial radio frequency treatments for postharvest pest control in in-shell walnuts

Current research on wireless radio frequency (RF) systems often makes unphysical simplifying assumptions and treats the associated signal processing and electromagnetic (EM) analyses independently, resulting in improper inclusion of the underlying physics (EM theory) of such systems and consequently leading to inaccurate and erroneous performance predictions. To achieve accurate modeling and predictions, EM theory and signal processing must be intelligently merged. Examples of such errors commonly appearing in both fields are the following: not including the platform on which an antenna is mounted, which leads to completely erroneous predictions of antenna coverage [1], a serious issue for designing relevant antennas for RF systems, and optimizing transmitted waveforms without including proper differentiability requirements imposed by Maxwellian electromagnetics yielding inaccurate and physically unrealizable waveforms [2]. Because discussions of these topics appear in [1] and [2], this article concentrates on the different concepts of channel capacity and their implications and on the antenna and its relationship to the maximum power transfer theorem. Although the discussion addresses communication systems, much of it is applicable to noncommunication systems. A future of improved performance and better spectral harmony requires coding at RF, initially envisioned by Shannon and subsequently investigated by Viterbi, which is similar to the coding in global positioning satellite (GPS) and satellite communication. Such a methodology can also be carried out in radar in which, for example, a radar can transmit coded waveforms, such as a Barker code, to increase detection capabilities.

Under water acoustic (UAC) channel is subjected to large delay spread compared to radio frequency (RF) channels. In order to capture this large delay spread and avoid ISI, the UAC symbol duration needs to be considerably large reducing the transmission data rate. Unlike other RF systems, in Ultra-wideband (UWB) RF systems, small pulse width in the order of nano seconds is used to transmit information. This in turn, gives high resolution multipaths. In a time hopping UWB system, to avoid multipath overlap, the chip duration and the frame duration are kept equal to or larger than the maximum delay spread of the channel. This results in large UWB symbol duration and hence reduces the data rate. In order to increase the data rate, the chip duration, and frame duration can be reduced to less than the maximum delay spread. In addition, to farther increase the data rate, guard interval between consecutive symbols can be reduced/removed allowing consecutive symbols to overlap. This results in intersymbol interference (ISI). Surprisingly, this type of overlap doesn't degrade UWB system performance significantly. In this paper, the same concept is applied to various UAC channels. In order to increase the data rate, consecutive UAC symbols are allowd to overlap. Performance under ISI is then evaluated.

Background Silent cerebral thromboembolism (CE) in catheter ablation for atrial fibrillation (AF) is not rare. Prior our study has reported lower incidence of silent CE in AF radiofrequency (RF) ablation using irrigated-tip catheter than conventional 4 or 8mm-tip catheter. In addition, the incidence of silent CE in AF ablation under direct oral anticoagulant (DOAC) was equivalent to continuous therapeutic warfarin. Recently pulmonary vein isolation (PVI) using cryoballoon (CB) has emerged as an alternative technique to RF ablation because some studies suggested that the efficacy for PVI by CB was equivalent to RF. However, incidence of silent CE in CB ablation under the use of DOAC is unknown. Objective We aimed to evaluate the incidence new silent CE in AF ablation using CB system compared with irrigated RF system under the use of DOAC. Methods 322 consecutive patients with paroxysmal or persistent AF (155 using CB system, 167 using RF system) who underwent the first AF ablation were taking DOAC more than one month prior to the procedure. Throughout AF ablation procedure, heparin was administered to maintain activated clotting time (ACT) between 300 and 400 seconds. Head MRI was performed in all patients within 24 hours after the procedure. Results In 14 (9.0%) patients using CB and in 20 (12.0%) patients using RF, head MRI showed new embolic lesions without neurological symptom (P=0.469). Although the amount of heparin during the procedure in group CB was significantly less than in group RF (16134±3125 U vs. 18689±5222 U; P<0.0001), amount of heparin per hour in group CB was more than in group RF (8335±1955 U/h vs. 6143±1918 U/h; P<0.0001) because procedure time in group CB was shorter than in group RF (121.3±34.1 min vs. 189.5±47.4 min; P<0.0001). Mean ACT in both groups was maintained high level (3367±25.3 sec. vs. 338.6±23.5 sec.; P=0.479). In univariate analysis, minimum ACT during procedure, as before puncture of interatrial septum, were significantly correlated with the incidence of silent CE (P=0.027). Conclusions The incidence of silent CE in AF ablation using CB system was lower than RF system, although it was not a significant difference between different ablation techniques for AF. In AF ablation, the use of CB may be preferred rather than RF as ablation system in regard to risk reduction of thromboembolic complications.

Incorporating tool identification system in normal machining centre using radio frequency identification