Transmitter noise propagation in millimeter-wave and sub-terahertz: from limits to design guidelines

Official URL: https://dx.doi.org/10.1109/OJCOMS.2026.3730694

This paper presents an additive noise link-budget analysis for millimeter-wave (mm-Wave)and sub-Terahertz (sub-THz) communication systems, focusing on the propagation of transmitter(TX)-chain-generated additive noise when propagation loss is insufficient to suppress it below the receiverthermal and atmospheric molecular noise levels. The framework traces the frequency-dependent TXoutput-noise level through cascade gain, antenna gains, free-space spreading, atmospheric absorption, andbandwidth integration to the receiver input, and derives an analytical criterion for a specified signal-to-noise ratio (SNR) degradation level. Under the analyzed low-antenna-gain short-range configuration,propagated TX noise reduces the achievable SNR by approximately 13–18 dB at far-field-valid millimeter-scale separations, although the penalty decreases rapidly with distance and falls below 0.1 dB by 100 mmat the four representative frequencies evaluated. At 100 m, the nominal degradation is approximately 3.3 dBat 60 GHz and 1.7 dB at 140 GHz; at 1 km, the corresponding values are approximately 6.4 and 2.9 dB. At250 and 300 GHz, the nominal penalty falls below 1 dB at 100 m and becomes negligible at 1 km under theevaluated atmospheric conditions. Evaluation at four published silicon link configurations yields predictedpenalties ranging from 0.0017 to 7.10 dB under the stated TX-chain assumptions. These results show thatpropagated TX noise can become significant under certain link, hardware, and atmospheric conditions.