Masters Theses


Qian Liu

Keywords and Phrases

Common Mode Filter; EMI; Heatsink; Lossy Material; Electromagnetic Band Gap


"This thesis consists of four papers. In the first paper, two new common mode filter structures were designed, fabricated, and measured. A "sandwich-type" EBG structure that resonates at the desired filter frequency is designed to suppress common mode filter on differential signals. The new filters are placed on top of the PCB as a surface-mount component, instead of being implemented within the PCB stackup. The total radiated power (TRP) of the implemented filter is investigated and discussed. RF absorbing material and traditional shielding are considered to reduce the TRP.

In the second paper and third paper, new PCB-embedded common mode filters are designed and investigated. Based on a quarter-wavelength resonator, an inter-digital structure is designed having an electrical size of only 0.15 λ x 0.065 λ, where λ is the effective wavelength in the CM filter. Its interdigital structure is also capable of suppressing higher order harmonics of the CM signal and can be used for USB 3.0 to mitigate electromagnetic interference. Further, a novel broadband suppression structure is described that uses magnetically lossy material to suppress the CM signal from 4.6 to 20 GHz without strongly affecting the intended differential signal.

In the fourth paper, a methodology for validating the parameters of magnetic absorbing materials was developed. The microstrip line test can be recommended as an easy-to-implement validation method for the measured material parameters. The heat sink model and simulation comparison has also been investigated to determine the radiation mitigation with lossy materials"--Abstract, page iv.


Khilkevich, Victor

Committee Member(s)

Pommerenke, David
Fan, Jun, 1971-


Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering


Missouri University of Science and Technology

Publication Date

Fall 2016

Journal article titles appearing in thesis/dissertation

  • Reduction of EMI due to common mode currents using a surface-mount, EBG-based filter
  • Common-mode filters with interdigital fingers for harmonics suppression and lossy materials for broadband suppression
  • PCB structure for common mode suppression on differential microstrip lines
  • Modeling absorbing materials for EMI mitigation


xi, 77 pages

Note about bibliography

Includes bibliographical references.


© 2016 Qian Liu, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Electromagnetic interference
Shielding (Electricity) -- Mathematical models
Electric filters -- Design and construction

Thesis Number

T 11067

Electronic OCLC #