Miquel Ribo

A genetic algorithm based method for source identification and far-field radiated emissions prediction from near-field measurements for PCB characterization

A new method for predicting the far-field radiated emissions and for finding the radiation sources of a device from near-field measurements is presented. It is based on the substitution of the original device by an equivalent set of elemental dipoles, placed over the main radiating sources, which radiate the same near-field (and therefore, far-field). This equivalent set of elemental dipoles is generated using a genetic algorithm. From the position and type of the equivalent elemental dipoles, the position of the actual radiating sources is determined. Since the field produced by an elemental dipole is known, the far-field radiation of the actual radiating source can be calculated. The new method has been tested using synthetic data and real measurements from the radiation generated by a modem PCB demonstrating its viability and usefulness.

Characterization of Power-Line Filters and Electronic Equipment for Prediction of Conducted Emissions

With present-day standards and measurement techniques, it is very difficult to accurately predict the conducted interference levels of an electronic device connected to a power-line filter (PLF). In this paper, a new modal model (which takes into account common- and differential-mode interactions) for an electronic device is presented and tested. This model is used to develop a new methodology for the accurate prediction of the conducted emissions generated by a filtered electronic device. The modal point of view clarifies such phenomena as the loss of efficiency of PLFs and the modal energy exchange due to mismatches and asymmetries in the circuits. This methodology allows an automatic software selection or design of the optimum PLF for a given electronic device. It has been successfully tested using both test devices and actual electronic equipment.

Circuital and Modal Characterization of the Power-Line Network in the PLC Band

With present day measurement techniques, it is very difficult to accurately model the power- line network (PLN), as seen from its power-line terminals, both in terms of impedance and noise. In this paper, a new circuital model (that considers line-ground and neutral-ground signals) and a new modal model (that considers common and the differential mode signals) for characterizing the low voltage PLN are presented. These models, which treat impedance and noise in a unified way, are composed by a three-impedance pi-network and two voltage sources. These models, which are complete and rigorous, are very interesting to desing PLC modems matched to the PLN for maximal power transfer, to compute the energy conversion between common mode and differential mode produced by asymmetries in the PLN, and to know the levels of differential mode noise that will affect a PLC receiver. These models have been experimentally validated.

Modeling of radiating equipment by distributed dipoles using metaheuristic methods

This paper presents a method useful to extract a dipole model of radiating equipment. This model is used to predict the far-field radiated emissions from near-field measurements. The model of the EUT is an equivalent set of infinitesimal dipoles distributed inside a volume enclosing the EUT. The position, orientation and excitation current of each dipole of the equivalent set is obtained by means of a metaheuristic algorithm. The usefulness of the method is demonstrated by real measurements

Scattering Parameters-Based Channel Characterization and Modeling for Underground Medium-Voltage Power-Line Communications

Power-line communications (PLC) technologies rely on the power grid for data transmission. Since the communications channel is already deployed, this communication alternative is specially interesting for the power grid owner (i.e., the electrical utility). The medium-voltage (MV) distribution network, located after the last step-down electrical substation with typical levels from 6 to 25 kV, directly feeds large consumers and small ones through several transform stations. The growing interest on MV-PLC technology, the natural aggregation point for data coming and going into the low-voltage (LV) network, faces the same issue that the LV-PLC technology did (and does): standardization. In this way, a properly implemented channel model will allow the design of suitable modulation and access methods. This paper proposes a deterministic channel model for the MV underground network transfer function, based on a complete set of measurements performed in an MV urban ring. Moreover, the characterization of the MV-PLC channel elements as well as the noise scenario and access impedance have been carried out.

A genetic algorithm based method for predicting far-field radiated emissions from near-field measurements

A novel method for predicting the radiated emissions of a device from near-field measurements is presented. It is based on the substitution (using a genetic algorithm) of the original device by an equivalent set of elemental dipoles, which radiates the same near-field (and therefore, far-field). Since the field produced by a dipole is known, the far-field radiation of the actual radiating source can be calculated. This avoids the use of large semianechoic chambers to measure far-field since it is deducted from the near one. Moreover, this method allows the identification of the radiating sources. Simulations show the viability and usefulness of the new method.

MEMS-Based 180

In this paper, a new uniplanar 180° phase switch suitable for space differential radiometers is proposed. It is based on two dc-contact-microelectromechanical system (MEMS) single-pole-double-throw switches that switch between two different back-to-back coplanar-to-slotline transitions. Since these transitions are multimodal structures, rigorous multimodal models are developed to analyze them and to assess the effects of the unwanted coplanar odd mode. These models are capable of predicting under what conditions the transitions produce a good wideband, 180°-phase-shift and/or matching behavior; they are applied to the design of the 180° phase switch. A compact implementation of the phase switch in the frequency range 14-20 GHz is fabricated using the FBK-irst eight-mask surface micromachining process, featuring a 180° phase-shift bandwidth of 35% for a maximum phase error of 5° and insertion loss better than 2 dB. Experimental results show a very good agreement with the multimodal model predictions. The designed dc-contact MEMS switches fulfill the typical requirements of differential radiometers, featuring measured mechanical switching and release times of 100 and 15 ¿s, respectively.

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In this paper, a new methodology to characterize common-mode chokes is presented. It is based on a model where common-mode and differential-mode interference is separated into different ports. This methodology is used to explain modal conversion inside common-mode chokes, predict the common-mode and differential-mode conducted emissions when common-mode chokes are connected to electric devices, and improve the filtering performance of common-mode chokes by finding the optimal common-mode choke parameters.

Phase Switch for Differential Radiometers

A new technique to predict the small signal behavior of EMI power-line filters is presented. This technique is based on S-parameter measurements performed at all the terminals of the power-line filter. These measured S-parameters are converted to a set of modal S-parameters using the presented analytical matrix expressions. The modal S-parameter matrix completely models the small signal behavior of the power-line filter in terms of line and load common and differential modes. From this matrix, information such as common and differential mode insertion loss, modal behavior of the filter at different line and load impedances, and energy transfer between any combination of modes can be obtained.

A Modal Model of Common-Mode Chokes for Conducted Interference Prediction

In this paper, a new compact broadband uniplanar 180° phase switch, based on an air-bridged coplanar-waveguide (CPW) cross loaded with two capacitive-contact microelectromechancial systems (MEMS) switches in opposed (on/off) states, is presented. The two phase-switch states (0°/180°) are defined by actuating the MEMS switches from on/off to off/on. The asymmetry in the states of the MEMS switches results in a complex multimodal interaction between the two fundamental even and odd CPW modes at the air-bridged cross. Using the multimodal theory, the phase switch is analyzed, its frequency-in dependent 180°-phase-shift properties are proven, and a set of design equations for perfect port matching are derived. A multi modal circuit model for the phase switch is then presented, and design equations and conditions for compact phase switches are derived. Finally, a very compact phase switch is designed and fabricated using an eight-mask surface micromachining process, featuring a measured phase shift of 180° ± 1.8° in a very wide frequency range (1-30 GHz) and an insertion loss better than 2.1 dB in the design band (10-20 GHz). Experimental results are in very good agreement with electromagnetic and multimodal circuit simulations, thus validating the proposed approach and design procedure.