Asmmetric Coplanar Waveguide Equi-Impedance Conditions And Its Applications

In recent years, the importance of CPW has been widely accepted by academic world, and continuous attentions have been taken in this field. Many research achievements have been made related to CPW, including basic characters of CPW, CPW discontinuities, modified CPW structures, and CPW circuit devices like couplers, filters, etc. As the expansion of CPW, ACPW is a concept with more generalities, and gained more and more attentions in these years. However, researches on ACPW are not as popular and deep as traditional CPWs, further studies, like synthesis of ACPW, are required.This paper studies on various CPW and ACPW transmission lines in a deep-going way, including ideal model of CPW, ideal model of ACPW, CPW and ACPW with finite substrate thickness, CPW and APCW with conductor-backing; discussed simplified conformal mapping formula of ideal ACPW and ACPW with finite substrate thickness, via direct mapping method.Proposed the concept of Equi-Impedance-Condition, and given the Equi-Impedance-Condition of ideal CPW and ACPW. Large extent in this paper used to discuss the CPW-ACPW Equi-Impedance-Condition for the case of Equi-conductor width, Equi-slot width, and Equi-ground to ground distance. Derived synthesis formula of ideal CPW on the basis of proposed function RoE-1, and derived synthesis formula of ideal ACPW employing Equi-Impedance-Condition. Discussed application ranges of various parameter expressions, their restrictive relationships, and influences on characters of transmission lines.Proposed novel PS CPW and PBG-CPW transmission lines, analyzed its characters with the help of CPW and ACPW conformal mapping formulas. As a type of non-uniform transmission line, PBG-CPW can be treated as uniform transmission line under certain conditions, and can be designed and analyzed by proposed effective character parameters.Studied on ACPW bend, which is a type of ACPW discontinuities. Proposed CPW-ACPW bend structure and CPW-ACPW bend with conductor backing under CPW-ACPW Equi-Impedance-Condition, and analyzed its characters. These structures can compensated the intrinsic distant difference in traditional CPW bend, while homogeneous impedance character also obtained, which is good for circuit performance.Many problems, like crosstalk, EMC, mode conversion, etc. can't be analyzed in theoretical way, so when dealing with these problems, EM numerical method always employed. FDTD method is proven suitable in solving CPW and ACPW problems, therefore this paper studies on excitation problems of CPW and ACPW in FDTD calculations, proposed ACPW excitation model, and given expressions of exciting location for CPW and ACPW, via massive electromagnetic simulations.Proposed novel ACPW ultra-wideband filter and ACPW-DGS filter, analyzed these structures. ACPW ultra-wideband filter can cover the frequency band of UWB exactly, while have a good stop-band character and facilitate to design. The proposed ACPW-DGS filter doesn't present significant improvement in compare with CPW-DGS filter, but has more design flexibility, and the model of ACPW-DGS covers CPW-DGS, has more generality.The paper proposed synthesis formula of ideal CPW and ACPW on the basis of approximate formula of RoE-1 and used these formulas in later contents for validation. It was proved that even for some case of finite substrate CPW or ACPW; proposed formulas can achieve acceptable accuracy.