Open AccessA wire‐crossed‐loop resonator for rapid scan EPR
Author(s) -
Rinard George A.,
Quine Richard W.,
Biller Joshua R.,
Eaton Gareth R.
Publication year - 2010
Publication title -
concepts in magnetic resonance part b: magnetic resonance engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.286
H-Index - 32
eISSN - 1552-504X
pISSN - 1552-5031
DOI - 10.1002/cmr.b.20161
Subject(s) - resonator , acoustics , noise (video) , bandwidth (computing) , helical resonator , materials science , physics , nuclear magnetic resonance , optics , computer science , telecommunications , artificial intelligence , image (mathematics)
A crossed‐loop (orthogonal mode) resonator (CLR) was constructed of fine wire to achieve design goals for rapid scan in vivo EPR imaging at VHF frequencies (in practice, near 250 MHz). This application requires the resonator to have a very open design to facilitate access to the animal for physiological support during the image acquisition. The rapid scan experiment uses large amplitude magnetic field scans, and sufficiently large resonator and detection bandwidths to record the rapidly‐changing signal response. Rapid‐scan EPR is sensitive to RF/microwave source noise and to baseline changes that are coherent with the field scan. The sensitivity to source noise is a primary incentive for using a CLR to isolate the detected signal from the RF source noise. Isolation from source noise of 44 and 47 dB was achieved in two resonator designs. Prior results showed that eddy currents contribute to background problems in rapid scan EPR, so the CLR design had to minimize conducting metal components. Using fine (AWG 38) wire for the resonators decreased eddy currents and lowered the resonator Q , thus providing larger resonator bandwidth. Mechanical resonances at specific scan frequencies are a major contributor to rapid scan backgrounds. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 37B: 86–91, 2010