Strong Fiske type resonance peaks have been observed in current–voltage curves ofmtsp;YBa2Cu3O7step edge junctions onmtsp;LaAlO3substrates. We determined effective shunting capacitances from the voltages of the resonances. These data compare well with those obtained from the McCumber constantmtsp;&bgr;c. Typical values of the shunting capacitance per unit area for these junctions were estimated to be in the range of 20–30mtsp;fF/&mgr;m2. The surface resistance normalized to 1 GHz at the conjugating junction interfaces was estimated to be in the range of 1–3 &mgr;&OHgr;. ©1995 American Institute of Physics.