Eta Car is a variable star surrounded by a cloud of gas and dust that absorbs a large part of its optical emission and that showed, in the past two hundred years, several events of mass ejection. It presents a 5.52 year period in the high excitation Heλ 10830 line intensity, indicating periodic changes in the ionizing radiation. Changes in the central velocity of optical lines, with the same periodicity, suggests the presence of a companion star, in a binary orbit. At radio frequencies, the region shows an optically thick bremsstrahlung spectrum, extending to millimeter and submillimeter wavelengths, and strong recombination lines at low quantum numbers showing maser effects. The flux densities, both from the continuum and recombination lines show a periodic behavior similar to that observed at optical wavelengths. We present observations of radio continuum and recombination lines at different millimeter wavelengths for several epochs. Based on these observations we modeled the emitting region as a thin disk and determined its temperature, electron density and velocity distributions using the radiation transfer equations in NLTE.