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Type IV radio burst has been studied for over 50 years. However, thespecifics of the radio emission mechanisms is still an open question. In orderto provide more information about the emission mechanisms, we studied a movingtype IV radio burst with fine structures (spike group) by using the highresolution capability of Low-Frequency Array (LOFAR) on Aug 25, 2014\textbf{(SOLA-D-21-00188)}. We present a comparison of Nan\c{c}ay RadioHeliograph (NRH)and the first LOFAR imaging data of type IV radio burst. The degree of circularpolarization (DCP) is calculated at frequencies in the range 20$\sim$180 MHzusing LOFAR data, and it was found that the value of DCP gradually increasedduring the event, with values of 10\%$\sim$20\%. LOFAR interferometric datawere combined with white light observations in order to track the propagationof this type IV. The kinematics shows a westward motion of the radio sources,slower than the CME leading edge. The dynamic spectrum of LOFAR shows a largenumber of fine structures with duration of less than 1s and high brightnesstemperature ($T_\mathrm{B}$), i.e. $10^{12}$$\sim$$10^{13}$ K. The gradualincrease of DCP supports gyrosynchrotron emission as the most plausiblemechanism for the type IV. However, coherent emissions such as ElectronCyclotron Maser (ECM) instability can be responsible for small scale finestructures. Countless fine structures altogether were responsible for such high$T_\mathrm{B}$.

Interferometric imaging, and beam-formed study of a moving Type IV Radio burst with LOFAR