Miniature circulators for microwave superconducting systems

Ultraminiature high performance lumped element high temperature superconductor (HTS) circulators have been successfully demonstrated. Epitaxial HTS YBCO films have been deposited by pulsed laser deposition (PLD) onto buffered Yttrium Iron Garnet (YIG) substrates with measured surface resistance values (<1 m/spl Omega/ at 10 GHz @ 77 K) comparable to those of HTS films on lanthanum aluminate. The lumped element circulators occupy an area about an order of magnitude smaller in size than that of conventional disc junction circulators. Excellent low loss (<0.23 dB) and high isolation (>30 dB) over 5% bandwidth have also been demonstrated.<
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