By now, the neurophysiological effect of electromagnetic field (EMF) exposure and its underlying regulating mechanisms are not well manifested. In this study, we aimed to investigate whether acute long-term evolution (LTE) EMF exposure could modulate brain functional connectivity using regional homogeneity (ReHo) method and seed-based analysis on resting-state functional magnetic resonance imaging (fMRI). We performed the LTE-EMF exposure experiment and acquired the resting-state brain activities before and after EMF exposure. Then we applied ReHo index to characterize the localized functional connectivity and seed-based method to evaluate the interregional functional connectivity. Statistical comparisons were conducted to identify the possible evidence of brain functional connectivity modulation induced by the acute LTE-EMF exposure. We found that the acute LTE-EMF exposure modulated localized intra-regional connectivity (p < 0.05, AlphaSim corrected, voxel size ! 18) and inter-regional connectivity in some brain regions (p < 0.05, AlphaSim corrected, voxel size ! 18). Our results may indicate that the approaches relying on network-level inferences could provide deeper insight into the acute effect on human functional activity induced by LTE-EMF exposure. Bioelectromagnetics. 40:42-51, 2019.
This paper presents a novel planar balanced bandpass filter (BPF) with wideband common mode (CM) noise suppression and in-band CM noise absorption using coupled lines (CLs) with short-circuited stubs to realize high selectivity and wideband differential mode (DM) filtering performance. Two one-quarter wavelength stubs loaded with grounded resistors are introduced to realize wideband CM noise suppression. Thus, CM noise can be suppressed under a certain level at all frequencies. Four resistors are used to achieve CM noise absorption by dissipating the CM noise into heat, which can avoid the noise being reflected to the communication system and realize a wide absorption bandwidth with 90% absorption efficiency. For demonstration, an absorptive balanced BPF operating at 3.5 GHz with wide 3-dB fractional bandwidth (FBW) of 79.43% is fabricated and experimentally validated. It is worth noted that the absorptive balanced BPF can realize broadband CM noise suppression from 0 to 8 GHz, and the CM noise is well absorbed more than 10 dB from 2.41 to 4.63 GHz. Besides, wideband CM noise absorption with 90% efficiency from 2.51 to 4.60 GHz is realized, which indicates potential applications in improving the performance of the balanced radio frequency (RF) circuits. Good agreements between the simulated and measured results are observed.
In this paper, a novel rat-race coupler with smooth in-phase and out-of-phase performance is proposed. The structure is based on two sections of strong coupling coupled-lines. A weak coupling coupled-line is connected between the two sections on the upper line in series, and another is connected between the two sections on the lower line in shunt. In the working band, it has strong coupling, good impedance matching, and good isolation. The in-phase and out-ofphase performance is very smooth. It does not require multilayer structures, via-holes, or other complex structures. To verify this idea, a rat-race coupler on the 1.524 mm Rogers RO4350B substrate is realized. The simulated and measured results are in good agreement with the theoretical ones. It can achieve a 10-dB fractional bandwidth of 23.98% (3.12-3.97 GHz) and 45.44% (2.5-3.97 GHz), and maximum phase deviations of ±6 from 2.94 to 4.11 GHz.
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