| Summary: | A micro-scale 3dB high power RF (Radio Frequency) balance 4 Ports Bridge of MRI (Magnet Resonator Imaging) is realized with 3D PCB manufacturing and integrated capacity and theoretical calculation in this paper . At first a analysis method is proposed based on transmission line theory of the 1/4-wavelength and the lump and transmission parameters, and the transmisson line length and lump components of capacitors value are gotted for this micro-scale bridge. Then this Micro-Balance Bridge (MBB) manufacturing with FR4 and overall size is 100mm 60 mm 1 mm, and it size reduce 1/3 compared with plane bridge. MBB could be achieved 2 ways amplitude balance is about 0.1dB, phase balance is 1 , insert loss is about 0.3dB, flatness is not more than 0.01dB on the operate frequency of 64MHZ 5MHZ. This bridge could be supported input pulse power more than 1000 W by temperature experiment result. Use MBB integrate into the MRI systems and make imaging experiment and could reduce 20% imaging time from 1.2 ms to 900us, and it has good efficiency and homogeneity.
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