| With the deterioration of the electromagnetic environment,the coupling response analysis of transmission line systems under external field excitation has become an important research topic in the field of computational electromagnetics and electromagnetic compatibility.Microstrip interconnection is an important component of field-line coupling in high-speed PCB and its coupling response with uniform plane wave has been widely studied,and among them,the worst-case analysis of the coupling response is particularly important for the study of the normal operation of the chip device.At present,field-line coupling studies are commonly carried out for overhead cable structures and two-conductor structures,while the worst coupling situation for microstrip structure terminals is less analyzed.It is common to use cyclic iteration algorithm to obtain the value of the worst-case coupled voltage(WCV)of the microstrip structure terminal,but the specific analytical expression cannot be obtained,and the wave angle relationship determination and characteristic analysis of the incident excitation in the worst coupling scenario are lacking.The computational efficiency of solving the coupled response multiple times and then processing the data is often less efficient.Therefore,this paper mainly analyzes the worst coupling situation of microstrip structure terminals in high-speed PCB:we elaborate how to obtain the calculation formula of WCV value,and how to analyze the influence of microstrip line parameters,incident location and bandwidth energy on WCV numerical calculation.In addition,the relationship between the effective coupling rate and the wave angle of incident excitation in different coupling scenarios is also summarized and analyzed.The work of this article is mainly carried out from the following aspects:(1)Starting from the classical BLT equation,the worst coupling characteristics of the microstrip structure terminal are analyzed,and the coupling voltage resonance frequency formula and the wave angle relationship characteristics of the incident excitation are derived.In this paper,we determine the worst coupling situation and the minimum coupling situation of the microstrip terminal response through the frequency band division,analyze the resonant frequency position and incident position analysis in each case by the accurate solution form of the terminal coupling response,calculate the effective coupling rate in each case,and visually describe the wave angle relationship of the incident excitation under the minimum coupling situation.(2)The acquisition of numerical analytical solutions for microstrip structure terminal WCV under field excitation is introduced.Aiming at the worst-case spectrum analysis theory when the applied excitation field acts on the transmission line structure,the numerical calculation formula of WCV in the overhead cable structure is derived.Based on the calculation formula and the response frequency domain solution of the microstrip structure terminal,we obtains the WCV calculation formula of the microstrip structure terminal.In the follow-up paper,we continue to analyze how line parameters,incident excitation and bandwidth energy affect the WCV values,and pass the simulation verification.Finally,the worst coupling of microstrip structure terminals under high-power electromagnetic(HPEM)pulse excitation is studied.(3)The field-line coupling equivalent circuit model is used to quickly and intuitively acquire the WCV of the microstrip structure terminal during random incident excitation.In this paper,the field problem is transformed into a road problem by the equivalent circuit model,and the solution of each coupling response is calculated by setting the sweep variable parameters,combined with the incidence angle at low frequency,the polarization angle information and the effective coupling rate calculation formula at high frequency,the envelope structure of the overall coupling response is solved,that is,the numerical size of WCV. |
