By Marcus C. Walden
Abstract: This paper presents the antenna G/T degradation incurred when communications systems use very inefficient receive antennas. This work is relevant when considering propagation predictions at HF (2-30 MHz), where it is commonly assumed that antennas are efficient/lossless and external noise dominates over internally generated noise at the receiver. Knowledge of the antenna G/T degradation enables correction of potentially optimistic HF predictions. Simple rules-of-thumb are provided to identify scenarios when receive signal-to-noise ratios might be degraded.