Multi-and dual-tuned microstripline-based transmit/ receive switch for 7-Tesla magnetic resonance imaging

Abstract

This article introduces two new designs of transmit/receive switches for 7-Tesla magnetic resonance imaging. Both designs based on a microstripline coupler technology. In the first design, a different single frequency signals can be handled to/from a radio frequency coil using smart tuning network. In the second design, a dual-tuned 1H/23Na transmit/receive switch is designed to handle a dual resonant signal to a dual resonant 1H/23Na coil, simultaneously and without tuning. In transmit and receive, the first design achieved good matching (-20 dB), and low insertion loss (0.78 dB) for the 1H, 19F, 31P, 13C, and 23Na magnetic resonance signals with high isolation (61 dB). Similarly, the dual-tuned 1H/23Na switch achieved good matching (<À11.5 dB) and low insertion loss (1.0 dB) with high isolation (67 dB), whereas for 1H/31P switch, good matching has been achieved (<À12 dB) and low insertion loss (0.96 dB) with high isolation (62 dB). The first proposed switch enables the use of the same switch with different coils resonating at Larmor frequencies of different atomic nuclei. The second switch can handle a dual resonant signal to a single dual resonant coil. The first design is promising in reducing the costs by using the same switch with different coils. The second design is promising in the integration with multichannel dual resonant coil. K E Y W O R D S hybrid coupler, magnetic resonance imaging, PIN diodes, radio frequency