title: Note: High precision measurements using high frequency gigahertz signals.
abstract: Generalized lock-in amplifiers use digital cavities with Q-factors as high as 5 × 10(8) to measure signals with very high precision. In this Note, we show that generalized lock-in amplifiers can be used to analyze microwave (giga-hertz) signals with a precision of few tens of hertz. We propose that the physical changes in the medium of propagation can be measured precisely by the ultra-high precision measurement of the signal. We provide evidence to our proposition by verifying the Newton's law of cooling by measuring the effect of change in temperature on the phase and amplitude of the signals propagating through two calibrated cables. The technique could be used to precisely measure different physical properties of the propagation medium, for example, the change in length, resistance, etc. Real time implementation of the technique can open up new methodologies of in situ virtual metrology in material design.
authors.affiliation: Department of Electrical and Information Technology, Lund University, Ole Römers väg 3, 22363 Lund, Sweden.
authors.forename: Aohan
authors.initials: A
authors.lastname: Jin
authors.affiliation: Department of Electrical and Information Technology, Lund University, Ole Römers väg 3, 22363 Lund, Sweden.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Fu
authors.affiliation: Chemical Physics, Lund University, Getingevägen 60, 22241 Lund, Sweden.
authors.forename: Atsunori
authors.initials: A
authors.lastname: Sakurai
authors.affiliation: Department of Electrical and Information Technology, Lund University, Ole Römers väg 3, 22363 Lund, Sweden.
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Electrical and Information Technology, Lund University, Ole Römers väg 3, 22363 Lund, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Edman
authors.affiliation: Chemical Physics, Lund University, Getingevägen 60, 22241 Lund, Sweden.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Pullerits
authors.affiliation: Department of Electrical and Information Technology, Lund University, Ole Römers väg 3, 22363 Lund, Sweden.
authors.forename: Viktor
authors.initials: V
authors.lastname: Öwall
authors.affiliation: Chemical Physics, Lund University, Getingevägen 60, 22241 Lund, Sweden.
authors.forename: Khadga Jung
authors.initials: KJ
authors.lastname: Karki