VARICAPS FOR NMR RECEIVING COIL MATCHING AND SENSITIVITY CHANGES

Peter Andris - Ivan Frollo

   RF receiving coils for NMR imager must be exactly matched to the receiver. It is not possible without variable capacitors. In some cases variable capacitors can be replaced by varicaps and the coil can be tuned remotely. The quality of varicaps is not as high as the quality of good variable capacitors. The study of the influence of the varicaps quality upon the sensitivity of the receiving coil yielded the presented equations. Examples with several graphs illustrate the achieved results.

Keywords: structured and unstructured uncertainty, additive uncertainty, robust stability

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