[en] The authors have measured very low microwave losses in Y-Ba-Cu-0 fifth wave ring resonators. The authors deposited the Y-Ba-Cu-0 film on (1012) non-buffered sapphire substrates and patterned microwave circuits. High-Tc microstrip resonators demonstrated best Q-factor greater then 800 at 31 GHz, corresponding to surface resistances less than 3,0 mohm. Identical copper resonator showed Q's of 500 and surface resistance of 27 mohm. They show that the losses in the high loss samples can be accounted for by the presence of small fractions of c-axis-aligned grains highly misaligned in the plane of those films. Volume fraction of highly misaligned c-axis-oriented grains as 3% lead to losses above 3 mohm