Unmanned aerial vehicles (UAVs) have been penetrated into various markets. The control through cellular communication channels becomes of significant importance to ensure safely flying above densely ...populated areas. UAV s may suffer from electromagnetic interference (EMI) problems where their airframe is densely packed in a compact chassis with multiple electronic modules for power, control, and wireless communications. This paper describes the experiments on Electromagnetic (EM) emission within a compact (hobby or home) drone and the potentiality of EMI among the control and wireless modules once integrated in the same chassis. The EM waves were measured between 500 MHz and 6 GHz, with a folded long-hexagon antenna at 200 mm away from the drone in an anechoic box. It was observed that the drone emanated the EM waves up to -151 dBm/Hz in 800 MHz band. The influence on cellular communication performance was evaluated with a wireless communication system level simulator, showing the degradation by at most 15 dB in the minimum sensitivity if a receiver module exists in the same aircraft.
We report the case of a 28-year-old woman with type B chronic aortic dissection extending from a ductus diverticulum aneurysm. The patient was successfully treated by interposition of a Hemashield ...26-mm woven Dacron graft with a left posterolateral thoracotomy approach. Circulatory arrest through profound hypothermia and short retrograde cerebral circulation were employed during proximal anastomosis of the graft.
The 5 th generation (5G) communication system exploits millimeter-wave (mm-wave) frequency bands for high-speed and large-capacity cellular networks. Sub-mm-wave communication is severely challenged ...by the large path loss as well as the cable loss for attaining the certified performance level among receiver (Rx) and transmitter (Tx) chains, in comparison to sub-6 GHz counterparts. In addition, digital integrated circuits (ICs) for baseband functionality typically operate at the clock frequency in the order of GHz and emanate electromagnetic (EM) noises in a very wide range of frequency, which can impair 5G performance in a sub-mm-wave band. This paper exhibits the presence of high-order harmonics of digital switching noises from 22 GHz to 30 GHz. The near-field EM noise measurements using a sub-mm-wave down converter demonstrate the fact where the emission noise from digital ICs clocked at 1 GHz potentially becomes the root cause of EM interference in a cellular system using 30 GHz or even higher.
Near-field undesired radio waves are measured for electronic systems of interest that involve semiconductor switching circuits, and recorded in a noise database for evaluation of wireless ...interference at different locations or even in later developments of wireless terminals. Undesired radio waves are restored from the database as if a wireless terminal is placed nearby noise emitting systems, and analyzed with regard to their interference to wireless communication channels by using fully behavioral or hardware-in-the-loop simulation of wireless systems. A wireless power transfer (WPT) system for contactless charging of the batteries on electric vehicles (EVs) utilizes high-speed switching transistors for power converters/inverters as well as for digital controllers with switching logic circuits. The near field undesired radio waves recorded on-site at an anechoic chamber exhibit clear impacts on the data throughput of long-term evolution (LTE) wireless channel in off-site wireless system simulation with playback from the noise database.
Magnetic composite sheets of ferrite powders suppressed the undesired RF electromagnetic noise emission in a flip-chip semiconductor IC chip package. Their effects were evaluated by the measurements ...with Si demonstrators and the improvements on wireless communication performance were simulated at the wireless system level. The effectiveness was found to be dependent on the composites -- BaZn-Y hexagonal ferrites exhibited noise suppression by 7dB, which corresponded to the wireless performance improvements by 8dB in the 800 MHz band when the long term evolution (LTE) wireless system is assumed.
NiCuZn spinel ferrite particles were sintered into 50 μm-thick plate and mounted in between IC die and its interposer to explore their suitability as electromagnetic noise suppressor up to 10 GHz. A ...50 μm thick Y-Type hexaferrite plate with density of 5.2 g/cm 3 exhibits the figure-of-merit, Ploss/Pin, as high as 0.27 at 7 GHz. The test ferrite plate was embedded in between IC chip and interposer using a newly developed pre-assembly technique. This was enough to suppress on-chip conduction noise and corresponding near field emission by 4-17 dB in wireless communication channels.
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