Observations of the active region NOAA 12182 obtained at 2–10 GHz on the RATAN600 radio telescope on October 06, 2014 are presented. The high-resolution measurements detected new case of a narrow feature near (4.2±0.2) GHz against the background of the smooth spectrum of the local source associated with the NOAA 12182 active region. This narrow-band emission is identified with a faint flare observed at UV-waves in tailing part of this active region. The characteristics of the observed line (lifetime 3 seconds, high brightness temperature of the order of several million Kelvin (MK), polarization degree ≈ 12.5% with dominant e-mode emission) suggest that the event was triggered by a span of fast particles
(Te ~ a few MK) along (or through) the plasma layer with magnetic field ≈ 500 G.