Improved design of modal filter for electronics protection

Abstract

A new structure of modal filter which is more relevant for lightning protection of electronics than previously considered structures is proposed. Decrease of modal filter length or increase of original pulse width by factor of 10 and increase of modal filter attenuation from factor of 2 up to factor of 5 is shown. Condition for equal magnitudes of decomposed pulses and analytic formula for their values against a ratio of even to odd mode characteristic impedances are derived. Dependence of these values on coupling is shown for practical parameters of the new structure based on FR-4. On the basis of the calculated data an experimental prototype of an improved modal filter has been made. An experimental investigation has been performed.

Simulation of asymmetrical modal filter with different segmentation

“…Previously we have developed and implemented the MF with symmetrical cross section for Fast Ethernet network protection [9]. However, for another application we come up with another (asymmetrical) cross section of a MF with strong broad side coupling, providing the best and the attenuation Development of necessary software was supported by the state contract 8.1802.2014/K of the Russian Ministry of Education and Science, modeling of coupled lines was supported by RFBR grant 14-29-0925, simulation of waveforms was carried out at the expense of RSF grant 14-19-01232 in TUSUR University.…”

“…High-power nanosecond and subnanosecond ultrashort pulses are especially dangerous, as they can penetrate into various electronic equipment, being insignificantly attenuated by traditional protection devices [5][6][7]. Modal filters (MFs) are considered to be promising devices of protection against such interference [8,9]. MFs are passive protection devices based on coupled lines that decompose ultrashort pulses due to different speed of propagation of signal modes.…”

Pulse decomposition in the turn of meander line as a new concept of protection against UWB pulses

“…Further simulations were performed with l=30 mm to provide the condition (2). During the simulation the distance between the conductors s was being decreased to strengthen the couplings.…”

“…UWB pulse amplitude, depending on a line coupling, can be twice or more times lower than the initial one. For example, the article shows UWB pulse attenuation up to 5 times in the modal filter structure with a strong coupling in the inhomogeneous dielectric filling [2].…”

Contactless Modal Phenomena Based Approach to Detecting, Identifying, and Diagnosing of Electrical Connections

“…A number of theoretical studies have been carried out using the software for quasistatic and electromagnetic simulation showing the ability to apply modal phenomena for detecting, identifying, and diagnosing multiwire structures and to create devices based on these phenomena [12]. Moreover, there have been some experiments carried out to confirm that one pulse can be decomposed into several pulses with lower amplitudes because of different modal delays in the structure [13], with approaches to apply modal phenomena for protecting critical equipment against the effects of UWB-pulses propagation being described [14]. Experimental results on flat cable have demonstrated the possibility of contactless wire diagnostics using modal probing even without galvanic connection to the wire [15].…”