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See detailMixed Frequency Single Receiver Architectures and Calibration Procedures for Linear and Non-Linear Vector Network Analysis
Harzheim, Thomas UL

Doctoral thesis (2019)

In this thesis several new advancements in the field of linear and non-linear vector network analysis are presented. Three distinct but interconnected topics are addressed in this work: First the concept ... [more ▼]

In this thesis several new advancements in the field of linear and non-linear vector network analysis are presented. Three distinct but interconnected topics are addressed in this work: First the concept and feasibility of the single receiver vector network analyzer (VNA) architecture and the implications for existing error models are analyzed, starting with the one-port reflectometer, through two-port unidirectional 5-term, bidirectional 10-term and finally 7-term error models. New VNA error models, which are able to capture the effects of the leaky RF receiver input wave selector switch, are derived, along with new calibration and correction procedures for this architecture. Modifications to the existing test-set architectures are introduced to reduce the effects of the leaky RF receiver input wave selector switch and shorten the required measurement time in this VNA architecture. A purpose built 275 MHz to 6000 MHz single receiver VNA system based upon commercial-of-the-shelf components is presented and analyzed. Measurements carried out with this VNA system are used in conjunction with numerical test-set and VNA simulations to verify the efficacy of the new calibration and correction methods as well as different VNA test-set architectures according to EURAMET standards and procedures. The second main topic of this thesis is the introduction of phase repeatable synthesizers as a new calibration and correction phase reference standard for non-linear VNA measurements. Due to the high output power capability of this new phase reference standard, new non-linear test-set and measurement scenarios such as the full non-linear two port characterization of high power solid-state amplifiers become possible, which were out of reach before due to low system signal-to-noise ratios provided by comb-generator based sources in this setup. The third and final topic of this thesis integrates the contents and achievements of the two previous topics to prove and verify the feasibility of VNA based harmonic, i.e. non-linear, transponder-based stepped-FMCW radar systems operating directly in the frequency domain. A new stepped-FMCW theory based on mixed-frequency S-parameters is presented in conjunction with a phase-slope based ranging procedure which avoids time-domain transformation. A complete system-analysis and modeling of the harmonic radar system including the passive transponder tag is provided. Numerous high-resolution measurements are presented and analyzed to verify the validity and accuracy of the non-linear harmonic radar equation, to evaluate illumination and harmonic return signal polarization based propagation effects in a multi-path indoor measurement scenario and to demonstrate the performance of the harmonic radar system in severe clutter situations. [less ▲]

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See detailPhase Repeatable Synthesizers as a New Harmonic Phase Standard for Nonlinear Network Analysis
Harzheim, Thomas UL; Heuerman, Holger

in IEEE Transactions on Microwave Theory and Techniques (2018), 66(6), 2888-2895

In this paper, the synthesized phase reference standard is introduced as a new viable alternative to comb generator-based phase references for nonlinear vector network analyzer measurements. Emphasis is ... [more ▼]

In this paper, the synthesized phase reference standard is introduced as a new viable alternative to comb generator-based phase references for nonlinear vector network analyzer measurements. Emphasis is put on the achievable higher specific output power of a frequency picket of interest for a denser spacing in the reference frequency grid. Supporting calculations on network analyzer IF filter bandwidths and limits for a denser grid spacing for comb-based phase references are presented. The concept is evaluated with a reference prototype covering the frequency range of 54 MHz to 6.8 GHz requiring only a 10-MHz reference signal and no network analyzer generators for stimulus, thus enabling even 2-port network analyzers without direct receiver and generator access to perform nonlinear reflection measurements. Furthermore, a method for generating a low-jitter trigger signal for the oscilloscope in absence of the comb generator pulse is shown. The synthesized phase standard implementation and the characterization setup are described in high detail to facilitate reproducibility of the results. Characterization of the new phase standard is performed in a frequency hopping pattern for amplitude and phase values of the reference pickets with a sampling oscilloscope-based setup. Startup and steady-state measurements are provided. A steady-state relative phase repeatability better than 2° over power cycles and drift of 0.089 °/h at 4 GHz referenced to a synthesized 1-GHz fundamental is achieved. [less ▲]

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See detailAn adaptive biasing method for SRD comb generators
Harzheim, Thomas UL; Heuermann, Holger; Marso, Michel UL

in 2016 German Microwave Conference (GeMiC) (2016)

This paper presents an adaptive biasing method for step recovery diode based comb generators which are controlled by a software routine. The aim is to provide the maximum possible harmonic output power ... [more ▼]

This paper presents an adaptive biasing method for step recovery diode based comb generators which are controlled by a software routine. The aim is to provide the maximum possible harmonic output power for a given configuration and different input frequencies during input power variation. This increases the usefulness of comb generators as harmonic phase reference sources for non-linear VNA measurements in the millimeter wave range. The effects are studied on a SRD comb generator which is able to generate -30...-20 dBm harmonics in the 50 to 60 GHz range when wideband terminated. It is shown that depending on the combination of input power and frequency, different bias level behaviors for maximum harmonic output power over frequency exist. Data for maximum power level bias is provided for output frequencies up to 60 GHz. Additionally the effect of subharmonic comb frequency generation is demonstrated. [less ▲]

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