Recent trend shows that the reduced size couplers are becoming potential building blocks and have created a continuing demand for the growing wireless communications market. Therefore, this paper presents a new design and realization for reducing the size of the branch-line coupler using eight two-step stubs that operates at 2.45 GHz. In this study, the reduced size branch-line coupler has been implemented on a 4 × 4 Butler Matrix, which generally consists of branch-line coupler, crossover, and phase shifter. The simulation results are obtained by using the advanced design system (ADS) in terms of S-Parameter analysis and the phase difference between the ports. Moreover, this design is realized on a low-cost substrate, e.g., flame resistance board (FR4 Board). The obtained results show that the proposed design has reduced the electrical length of transmission line up to 50% and consequently, the area of the branch-line coupler has been reduced up to 30% from the normal size.
Deploying sub-6 GHz macro-cell networks overlaid by millimeter wave (MMW) small-cells is a promising method to accommodate the unprecedented growth of data traffic demands and user devices. Although such a hybrid network could provide seamless connectivity and achieve high-quality services, there is a need to ensure that the growing number of base stations (BSs) does not affect biological safety, especially when the BSs are operated at high frequencies. This paper focuses on an analytical framework to investigate the electromagnetic field (EMF) exposure in a cellular network with coexisting sub-6 GHz and MMW BSs using a stochastic geometry approach. Locations of sub-6 GHz and MMW BSs are modeled as Poisson point processes (PPP). By incorporating different channel propagation, antenna, and fading models for sub-6 GHz and MMW tiers, the incident power density (IPD) coverage probability and the average IPD are derived and validated by Monte Carlo simulations. The impact of various system parameters such as BS density, number of antenna elements, and blockage density are investigated to gain insights on the network scenario. The results demonstrate that the variation of the EMF exposure level closely depends on the BS density and the number of antennas deployed at the BS. The results also show that the receiver sensitivity has a significant impact on the average IPD. For the same receiver sensitivity, it is revealed that an MMW user is exposed to a higher average IPD level than the sub-6 GHz counterpart. The results are also compared with the existing international regulations.INDEX TERMS Electromagnetic field (EMF), millimeter wave, sub-6 GHz, stochastic geometry, Poisson point process, incident power density.
<span>The properties of insulation have been improved by many research and the ability of nanocomposite material that composes the characteristic of improving electrical performance due to the addition of nanofiller into the based material gets serious attention. Polarization and Depolarization Current (PDC) measurement that has the ability to assess the condition of HV insulations with the initial periods after a DC step voltage application was favoured compared to other non-destructive monitoring techniques. This paper presents the works on moisture absorption in LLDPE-NR nanocomposite with different amount and percentage of nanofillers. The study of PDC level of the LLDPE-NR compound, filled with different amount of SiO<sub>2</sub>, TiO<sub>2</sub> and MMT nanofiller using Polarization and Depolarization Current (PDC) measurement technique is the main objective of this research. These results show that sample A1 has the lowest polarization current value and sample </span><span lang="IN">B5 </span><span>has the lowest depolarization current value.</span>
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