  The measurement of positions and sizes of radio sources in the observations
of solar radio spectral fine structures in an M6.5 flare on April 11, 2013 were
observed simultaneously by several radio instruments at four different
observatories: Chinese Solar Broadband Radio Spectrometers at Huairou
(SBRS/Huairou), Ondrejov Radio spectrograph in the Czech Republic
(ORSC/Ondrejov), Badary Broadband Microwave spectropolarimeter (BMS/Irkutsk),
and spectrograph/IZMIRAN (Moscow, Troitsk). The fine structures include
microwave zebra patterns (ZP), fast pulsations, and fibers. They were observed
during the flare brightening located at the tops of a loop arcade. The dynamics
of the polarization was associated with the motion of the flare exciter, which
was observed in EUV images at 171A and 131A (SDO/AIA). Combining magnetograms
observed by the SDO Helioseismic and Magnetic Imager (HMI) with the homologous
assumption of EUV flare brightening and ZP bursts, we deduced that the observed
ZPs correspond to the ordinary radio emission mode. However, future analysis
needs to verify the assumption that zebra radio sources are really related to a
closed magnetic loop, and are located at lower heights in the solar atmosphere
than the source of pulsations.
