Multipurpose Portable Q-Band Bridge

The paper describes the design, implementation, and technical characteristics of a portable Q-band microwave (mw) bridge based on the Gunn diode with the potential use for electron paramagnetic resonance (EPR) and dynamic nuclear polarization (DNP) spectroscopies. The mw frequency can be electronically adjusted in the range of 36-38 GHz with the maximal mw output of 120 mW and electronic attenuation of 0-60 dB. The value of the mw frequency can be stabilized and changed via automatic frequency control for direct and alternating current. A self-written Matlab-based program allows tuning and operating the bridge through the RS-485 interface. Examples of the EPR spectra implemented into the magnetic system of the Bruker ESP300 commercial spectrometer are shown.