Design of Broadband T/R Switch for Magnetic Resonance

Abstract

Transmit/receive (T/R) switch is used to switch the transmission and reception channels in nuclear magnetic resonance (NMR) spectrometer, which is required high isolation of high-power signals and low insertion loss of NMR signals. In addition, the general narrowband T/R switch is no longer applicable in broadband magnetic resonance spectrometer. This paper presents a positive-intrinsic-negative (PIN) diode-based T/R switch design with low insertion loss (less than 1 dB), high isolation of high-power signals (more than 75 dB) and short switching time (1 μs) in broadband (10~100 MHz). Substituting the broadband T/R switch for the narrowband T/R switch of the general probe, the NMR signals of hydrogen and fluorine nuclei at two different frequencies were measured on a 0.5 T NMR spectrometer, which verified the broadband performance of the T/R switch.

Keywords

• magnetic resonance
• radio frequency front-end
• transmit/receive (t/r) switch
• broadband