An E-band dual-port frequency-scanned traveling-wave array antenna enabled by series-fed microstrip patches was demonstrated in this study. By varying the distance between adjacent radiated elements, the main beam can be adjusted to any desired direction angle. Subsequently, by integrating this mechanism with the traveling-wave array antenna, a frequency-scanned antenna with simple structure is developed, which presents an excellent alternative for E-band sensing and imaging applications. The proposed antenna was constituted by 16 identical series-fed rectangular patches and two input ports with the impedance transition structures between rectangular waveguide and microtrip transmission line. With the two different feeding ports, main beam of the fabricated antenna’s radiation pattern can scan from 14° to 22° or -14° to -22° over 75GHz to 79GHz.
In this paper, some novel converters are proposed to solve the drawbacks of traditional phase-shifted full-bridge (PSFB) converter. In the primary side of proposed converters, the FB inverter is divided into two half-bridge inverters and the large-sized transformer is replaced by two small-sized transformers. By employing this structure, the zero voltage switching range can be extended and the primary circulating current existing in the additional PSFB converter is removed. In the secondary side, various rectifiers can be adopted to suit for different applications. Moreover, the primary power can be continuously transferred to secondary side in the proposed converters, which contributes to the reduction of output filter requirement. The circuit configuration, operational principle and relevant analysis of proposed converters are introduced in this paper. Experimental results on two typical prototype converters are built to validate the theoretical analysis.
This letter proposes a new two-dimensional (2-D) PAPR reduction method to improve the peak clipping precision and the error vector magnitude (EVM) performance. On one hand, it conducts joint peak clipping for dual-band signals; on the other hand, it uses iterative noise filtering method to suppress peak regeneration and spectral spread caused by hard clipping. Simulation results show that when the PAPR of OFDM dual-band signal is reduced to 6.8dB, compared with the traditional 2-D PAPR reduction algorithm, the EVM value of the signal is reduced from 10.3% to 6.9%, which reflects less signal distortion.
This paper presents a multiplicator ZCS turn on boost converter with high-efficiency and high-voltage-gain. A resonant multiplicator structure combined with two-phase technique is provided. Based on this structure, the problem of switches turn-on loss and inductor current ripple is minimized. The voltage resonant multiplicator also shows a good scalability. And the presented prototype is well adapted for multiphase dc-dc converters. The converter is tested for an application requiring the output power of 100W∼500W, operating with 12V input voltage and 220V output voltage. The measured peak efficiency equals to 95.4% with the gain of 18.333.
The monitoring of football training can help players develop their game to perfect a particular shot or area of performance. In this paper, a battery-free piezoelectric sensing platform for football training is architected, embedded, and experimentally verified. The system is based on the flexible feature of the piezoelectric polyvinylidene fluoride (PVDF) thin film, which can make the sensors attach to the shoes closely. Eight special positions are chosen to place the soft sensors: one on the tip, two on the inside, two on the arch, two on the outside, and one on the heel. A linear relation between the inspired voltage and hitting pressure is found with the fitted sensitivity of 0.245V/N. Based on the piezoelectric Lead Zirconium titanite (PZT) patch under the shoes and the energy harvest circuit, the energy of sport movements can be collected and employed as a power source to support the sensing circuit. The system is also used in practical experiments and it is found not only the sensing pressure but also the hitting positions will influence the movement of the shotted ball. This work provides an innovated method to conveniently monitor motion and analyze the sports skills and use them in artificial intelligence and the Internet of Things (IoT) in the human health monitoring area.
This paper presents a dual-band matching network based on composite right/left-handed transmission line (CRLH-TL) unit cell to optimize the impedance matching of dual-band Doherty power amplifier (DPA). The number of CRLH unit cells in the matching network can be flexibly determined by theoretical calculation to achieve impedance matching at any two frequencies. Moreover, A dual-band DPA is designed and fabricated using GaN HEMT CGH40010H to verify the performance of the proposed network. The designed DPA can deliver a saturation output power over 43.3dBm and the drain efficiency (DE) over 55.2% in the frequencies of 2.6GHz and 3.5GHz. Meantime, the drain efficiency at the 5dB output power back-off (OPBO) is over 44% at 2.6GHz and 3.5GHz.
Power generation characteristics of a Si PV cell under extremely high optical power near-infrared irradiation were investigated for use in optical wireless power transmission. We used high power LED light sources with 730nm, 850nm and 940nm wavelengths and a condensing optics to realize 10-sun level extremely high optical power irradiation in the measurements. More than 0.22W electrical power was generated from a 1cm square Si heterojunction PV cell under about 1W/cm2 optical power irradiation. This is more than 10 times the power generation density of conventional Si solar panels. Estimated power conversion efficiencies under 10-sun power level near-infrared irradiation exceeded 22.5%, which indicate a potential for high-power wireless transmission with Si PV cells using near-infrared light.
In this paper, a novel quad-band branch line coupler with high ratio (from 6.27 to 14.96) of the largest operating frequency to the smallest operating frequency is presented. To realize quad-band operations, a combination of coupled lines and open stubs is proposed which can make the design flexible. By using analysis of even and odd modes, the equivalent equations for the quad-band operation are obtained. Compared to the existing quad-band branch line coupler, the proposed quad-band coupler has the highest ratio of the largest operating frequency to the smallest operating frequency, which is valuable for wideband and ultra wideband application. For practical applications, a quad-band coupler operating at 0.7, 1.64, 4.09, and 5.03GHz which can be used for the long term evolution (LTE) and Wi-Fi is designed, fabricated, and measured. The simulated and measured results agree well with the design theory.
This letter proposes a novel method to promote the heat dissipation of watch-type smart devices by using receiver coils for wireless charging. It is achieved by embedding a spiral coil inside the belt. The heat dissipation effects of the proposed method on temperatures at key hot spots are clarified. The power transfer efficiency is also clarified. In watch-type smart devices, the most critical part for temperature is the underside surface of the belt, since this is the part that touches the skin for a long time. The analysis results show that the proposed method can reduce the increase in ambient temperature at the belt’s underside surface by 59.7% and that its power transfer efficiency is more than 90%.
Large-sized cache is beneficial to improve CPU performance especially for IoT applications with huge amount of data. However, large-sized SRAM cache also increases chip area and energy which is not friendly to resources limited IoT terminals. The STT-RAM with high storage density and near zero leakage is regarded as an ideal technology to replace SRAM. Prefetching is a vital method to hide the access latency of off-chip memory. Nevertheless, traditional prefetchers for SRAM is inadequate for MRAM cache with read-write asymmetry. Aggressive prefetching for STT-RAM cache would cause cache congestion and dynamic energy rise because of STT-RAM long write latency and high write energy. In response to the above problems, this paper novelty proposes WANCP (Write-awareness Adaptive Non-volatile Cache Prefetch), which adaptively adjusts the prefetch aggressiveness according to the saturation of MSHR (Miss-status Handling Registers) in the L2 cache. Experiments show that, for applications that are sensitive to L2 cache capacity, the CPU performance with STT-RAM L2 cache can be improved by up to 33.2% and 10.9% on average compared to the same sized SRAM L2 cache. The proposed WANCP can further improve the CPU performance 0.4% on average, and reduce the prefetch energy by 9.4% on average.
A miniaturized lumped element branch line coupler with π-type equivalent circuit is proposed, the design of branch line coupler has been carried out for S-band. The lumped element in the branch line coupler is realized by TSV, and the coupler is simulated and verified by industrial simulation software HFSS. The results show that the return loss is greater than 19dB, the isolation is better than 20dB, and the insertion loss is less than 1.53dB at the frequency of 2.1-2.4GHz. The size of the miniature TSV-based branch line coupler is only 0.660×0.630mm2 (0.018×0.017λ2g).
Flash LIDAR is needed in order to take 3D images for obstacle avoidance and to measure relative distances and attitudes during lunar and planetary landings, surface exploration, and orbital rendezvous docking with spacecraft. Meanwhile, commercial Flash LIDAR is being developed for capturing 3D images required by autonomous cars and drones. We have developed a prototype 1K pixel 3D image sensor using Silicon-MPPC, which is capable of photon counting, as the light-receiving sensor . In this paper, we describe the basic structure, circuit configuration, functions, and evaluation results of the basic performance of the sensor.
This paper investigates the eigenfrequency of the induced current in airborne cables to evaluate the coupling effect of dual-factor on electromagnetic susceptibility of airborne cables. The airborne cable is situated in the scaled fuselage which has lower complexity compared with the aircraft model. Based on the single-factor approach, the simulation results indicate that the electromagnetic environment and the fuselage have little effect on the eigenfrequencies. With the variations of cable length and cable height above the ground, the eigenfrequencies will change significantly. Based on the dual-factor of cable length and height, two improved analytical expressions for the eigenfrequency are proposed.
To pursue higher precision and wider range of noninvasive vascular deformation measurement for medical diagnosis, this paper presents a photoacoustic measurement method based on the acoustic resonance perspective other than usual imaging-based method. In-vitro experiments were conducted for red-ink-filled soft tubes having diameter of less than 1mm embedded in a tissue-mimicking phantom. A 3-W laser diode and a 2-MHz ultrasound transducer together with an external compressing device were used. Percentage error of 4% was marked in estimating the inner diameter of tube samples. The results demonstrated that the proposed method was feasible to detect a sub-millimeter deformation for thin tubes with ultrasound transducer of relatively low center frequency and electronic circuit of limited temporal resolution.