  The growth of electromagnetic ion cyclotron waves (EMIC) due to a ring
distribution of Hydrogen ions is examined. Though these distributions are more
commonly implicated in the generation of equatorial noise, their potential for
exciting EMIC waves is considered here. It is shown that since the ring
distribution is non-monotonic in perpendicular velocity, the amplification
achieved by this instability is greater than bi-Maxwellian distributions for
typical anisotropies, because the waves can maintain resonance over a much
longer part of its trajectory. For ring speeds V_R close to the Alfven speed
V_A, the growth rate is maximum at parallel propagation but is much larger at
oblique angles compared with a bi-Maxwellian, and can have a second peak
approximately at kperp c/omegaPH V_R/V_A ~2.3 for ring speeds about the
parallel thermal speed. Strong wave gain is achieved for moderate ring speeds
V_R~V_A . The analysis suggests that EMIC wave activity should be closely
associated with equatorial noise.
