Power Dependent Impedance Measurement Exploiting an Oscilloscope and Möbius Transformation

Sonshu SAKIHARA  Masaru TAKANA  Naoki SAKAI  Takashi OHIRA  

IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.10   pp.918-923
Publication Date: 2017/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E100.C.918
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technology)
nonlinear impedance measurement,  Möbius transformation,  oscilloscope,  measurability,  RF rectifier,  

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This paper presents an approach to nonlinear impedance measurement exploiting an oscilloscope and Möbius transformation. Proposed system consists of a linear 4-port network and an oscilloscope. One of the port is excited by a high power source. The power is delivered to the second port, which is loaded with a DUT. Another set of two ports are used to observe a voltage set. This voltage set gives the impedance of the DUT through Möbius transformation. We formulated measurability M of the system, and derived the condition that M becomes constant for any DUT. To meet the condition, we propose a linear 4-port network consisting of a quarter-wavelength transmission line and resistors. We confirm the validity and utility of the proposed system by measuring the impedance of incandescent bulbs and an RF diode rectifier.