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In this article, we present a vector network analyzer (VNA)-based measurement scheme and setup to obtain repeatable phase spectrum measurements of 75–110-GHz modulated radio frequency (RF) signals. In order to remove the random phase contribution of sweeping local oscillator (LO) in harmonic downconversion, the LO signal is coupled out into an auxiliary measurement channel where its random phase at the fundamental can be derived after additional modulation and downconversion treatments. Afterward, a user-defined math equation is used inside the VNA for LO phase cancellation, based on the traces of RF- and auxiliary-channel raw measurements. The key point of the proposed LO phase cancellation technique is measuring the 75–110-GHz test signal and the auxiliary-channel signal at the same GHz intermediate frequency so that the receivers of VNA can measure both of them simultaneously when working on the peculiar continuous-wave or zero-span mode. According to the method validation at 78, 93, and 108 GHz, a phase fluctuation of ±2° for single-run measurements is found reachable in practice. [ABSTRACT FROM AUTHOR]

This paper proposes a practical approach for dense-spectral-grid phase measurements based on a nonlinear vector network analyzer (NVNA). With the multitone outputs of commercial VSGs as both phase references and standards, a modified NVNA is presented to effectively obtain the phase spectra of modulated RF signals with spectral resolution of 1–100 kHz. Due to the limited tone number of a VSG multitone standard, a multistep phase calibration method is also proposed in this paper for multiplying the calibratable tone numbers in practice. A phase accuracy of ±2° has been experimentally achieved with both the VSG-based approach and the multistep phase calibration method at 2.4 GHz on a 1–100-kHz spectral grid. [ABSTRACT FROM AUTHOR]

The step-recovery-diode-based impulse generator is a classical picosecond-level impulse-formation technique, whose strong harmonic nonlinearity under sinusoidal stimulus is widely utilized as the phase reference of the nonlinear vector network analyzer (VNA) (NVNA) and large-signal network analyzer for wideband measurements. This paper further exploits its intermodulation nonlinearity under multitone stimulus and proposes a new approach, rather than the traditional “harmonic” way, of the NVNA phase reference for future polyharmonic intermodulation measurements. Experimental results show that this method can provide plentiful intermodulation components around each harmonic available and is stable for NVNA use, with the advantages of flexible local frequency-resolution setup from tens of megahertz to less than hundreds of hertz. [ABSTRACT FROM PUBLISHER]

This paper studies the systematic uncertainties of nonlinear vector network analyzer (NVNA) measurements and presents a covariance-matrix-based method to analyze the uncertainty propagation from calibration standards and hardware to error model terms and effective measurements. Analytic deductions of the Jacobians for frequency-domain quantities are proposed, dealing with the complex NVNA measurements and calibration functions. An NVNA two-port-calibration uncertainty is put forward as a new kind of systematic uncertainty consideration for this vector-correction-based instrument. Experiments on our prototype NVNA show the necessity of using covariance-matrix-based uncertainty analysis, particularly for polyharmonic measurements, and reveal some features of NVNA uncertainty analysis due to the calibration techniques. [ABSTRACT FROM PUBLISHER]