Masters Theses


Arpit Kothari

Keywords and Phrases

RF coupler; Standing wave phase shift


"Recently, two novel single-port, phase-shifter based vector network analyzer (VNA) systems were developed and tested at X-band (8.2 - 12.4 GHz) and Ka-band (26.4 - 40 GHz), respectively. These systems operate based on electronically moving the standing wave pattern, set up in a waveguide, over a Schottky detector and sample the standing wave voltage for several phase shift values. Once this system is fully characterized, all parameters in the system become known and hence theoretically, no other correction (or calibration) should be required to obtain the reflection coefficient, (Γ), of an unknown load. This makes this type of VNA "calibration free" which is a significant advantage over other types of VNAs. To this end, a VNA system, based on this design methodology, was developed at X-band using several design improvements (compared to the previous designs) with the aim of demonstrating this "calibration-free" feature. It was found that when a commercial VNA (HP8510C) is used as the source and the detector, the system works as expected. However, when a detector is used (Schottky diode, log detector, etc.), obtaining correct Γ still requires the customary three-load calibration. With the aim of exploring the cause, a detailed sensitivity analysis of prominent error sources was performed. Extensive measurements were done with different detection techniques including use of a spectrum analyzer as power detector. The system was tested even for electromagnetic compatibility (EMC) which may have contributed to this issue. Although desired results could not be obtained using the proposed standing-wave-power measuring devices like the Schottky diode but the principle of "calibration-free VNA" was shown to be true"--Abstract, page iii.


Zoughi, R.

Committee Member(s)

Beetner, Daryl G.
Pommerenke, David


Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering


IEEE Instrumentation and Measurement Society


Missouri University of Science and Technology

Publication Date

Summer 2013


xiv, 133 pages

Note about bibliography

Includes bibliographical references (page 31).


© 2013 Arpit Kothari, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Electric network analyzers -- Design
Electric network analyzers -- Computer simulation
Detectors -- Calibration -- Computer simulation
Phase shifters -- Computer simulation
Spectral sensitivity -- Computer simulation
Diodes, Schottky-barrier
Spectrum analyzers

Thesis Number

T 10352

Electronic OCLC #