The paper presents and evaluates three advanced methods for the characterization of the low-voltage (LV) grid access impedance for the frequency range assigned to Narrow Band-Power Line Communications (NB-PLC): 9 kHz to 500 kHz. This study responds to the recent demand from both regulatory bodies and Distribution System Operators about the need for accurate and validated methods for this frequency band, due to the limited knowledge of the impedance values in the electrical grid and their influence on NB-PLC transmission channels. In this paper, the results of a collaborative work to develop different proposals to overcome the challenges for the proper characterization of the frequency and time-varying grid impedance, from different theoretical approaches, are presented. The methods are compared in a controlled and isolated scenario: the impedance characterization of passive filters. Then, the results are validated two-fold: first, against theoretical simulations, based on the schematics provided by the manufacturer, and second, against the measurement results of a precision impedance meter, used as a reference of accuracy. The results demonstrate a high degree of precision of the three proposals to characterize the access impedance of the LV grid.

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This paper presents the design, manufacturing and testing of a MEMS SP16T switch to be used in open loop reconfigurable antenna systems. It consists of the hybrid integration of #5 MEMS SP4T switches (realized on HR Silicon substrate) on a multilayer substrate. The bilayer structure allows one to avoid RF and DC signal crossovers that could degrade the switch performance. The device is provided with SMA connectors and Control Electronic Board to operate with standard 0-5V signals. A wideband device was developed, working from DC up to 10GHz. The switch has been designed using both circuital and full-wave EM models. The simulations are presented in comparison with the measured performance. The SP16T switch shows return and insertion loss better than 12dB and 3.2dB, isolation better than 24dB from 0 up to 10GHz. Tests on the actual antenna systems are on-going.