Abstract <p>A concept of the electron cyclotron emission diagnostic from the low field side of the T-15MD tokamak is presented. The diagnostic is intended for measuring the plasma electron temperature profile in the equatorial plane using the electron cyclotron emission spectrum of the extraordinary mode at the second harmonic of the electron cyclotron resonance frequency. To achieve this, it is planned to use a 96-channel heterodyne scheme with double frequency down-conversion in conjunction with a quasi-optical focusing system that would shape the received wave beam. Under typical expected plasma parameters, the limits of the applicability region of the diagnostic were estimated in the geometrical optics approximation. This region is limited by cut-off, insufficient optical depth, and harmonic overlap. The spatial resolution of the diagnostic also was estimated.</p>