The problem of improvement of input/output ports construction of conveyor belt microwave heating system is considered. Meta-materials can be applied for significant reducing of electromagnetic energy escape from microwave processing chamber. Meta-material considered in this paper consists of printed circuit boards with metallization as a set of split-ring resonators. Estimation of effective permittivity and permeability of the meta-material was performed by FDTD analysis of the microstructure following Nicolson-Ross-Wier approach. Numerical results show that both effective permittivity and permeability have negative values at the frequency 2.45 GHz at some sets of parameters of the geometry, and these values provide negative (left- handed) refraction, which can be used for preventing escape of microwave energy from processing chamber through conveyor belt port.