Broadband Transmit/Receive Switch for 3T and 7T Magnetic Resonance Imaging

Abstract

This article presents a transmit/receive switch that utilizes a broadband microstripline hybrid coupler. The proposed switch is suitable for application in both 3T and 7T magnetic resonance imaging. It operates within three frequency ranges, covering well-known X-atomic nuclei, such as 1H, 13C, 19F, 23Na, and 31P, at both 3T and 7T magnetic field strengths. For the 7T application, the switch simultaneously covers the corresponding X-atomic nuclei frequencies within two bands. However, for the 3T application, tuning is required to cover the corresponding X-atomic nuclei frequencies, particularly those below 60 MHz. The microstripline trace widths of the proposed switch were designed to prevent excessive temperature increases when exposed to 1 kW power of radio frequency pulses. The characteristics of the switch were obtained using the Momentum tool—an electromagnetic simulator supported by ADS software. The proposed switch was fabricated, with its measurement verification results demonstrating favorable return loss (>10 dB), high isolation (>40 dB), and low insertion loss (<0.8 dB) at all operating frequencies.

Keywords

• broadband
• hybrid coupler
• magnetic resonance imaging
• microstripline
• pin diode