Optimizing Measurement SNR for Weak Near-Field Scanning Applications


Conventional near-field scanning techniques often employ a general setup such as: broadband near-field probe output connected to a chain of amplifiers through a coaxial cable to a spectrum analyzer. In this paper, we investigated how the signal to noise ratio is influenced by the coaxial connection between the probe output and the first amplifier, types of probes, cooling the probes with liquid nitrogen and the amplifier's noise figure. Eliminating cabling between probe and first amplifier, and using a low noise amplifiers helped increase signal-to-noise ratio by ~10dB. Further, liquid nitrogen is used to cool down a tunable resonant probe. This increases quality factor of the resonance and improves sensitivity. Thus, SNR is further improved by 10-12dB compared to a similar broadband setup.

Meeting Name

2017 IEEE International Symposium on Electromagnetic Compatibility & Signal/Power Integrity (2017: Aug. 7-11, Washington, DC)


Electrical and Computer Engineering

Keywords and Phrases

Electromagnetic Compatibility; Global Positioning System (GPS); Global System for Mobile Communications; Liquid Nitrogen; Liquids; Low Noise Amplifiers; Magnetic Field Measurement; Nitrogen; Noise Figure; Probes; Scanning; Spectrum Analyzers; Near Field Probes; Near-field Scanning; Quality Factors; Resonant Probes; Signal to Noise Ratio (SNR); EMI; GSM; Magnetic Field Measurement; Probe Cooling

International Standard Book Number (ISBN)

978-1-5386-2231-5; 978-1-5386-2229-2

International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2017 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Aug 2017