A. D. Vinogradov, I. I. Malychev, P. A. Mozgovoy

The article analyzes the noise characteristics of the receiving compact active non-resonant single-turn loop antennas high-frequency wave (HF) range. In the high-frequency band signal to noise ratio is actually determined by the level of intrinsic noise devices, and the problem of designing active antennas is the maximum possible decrease in self-noise device. In the range of HF outside noise, as a rule, exceed the internal noise of active elements and devices, making low-noise devices, this option loses its meaning because sensitivity level is lower than the noise level and the device can not fully realize the inherent in his capabilities.To be adequate, unambiguous and rational assessment of active antennas in HF band conditions actually existing at a given place or predicted noise situation prompted the notion of « effective radio-noise field intensity property » and «equivalent to the noise factor»active loop antenna. Active antenna is considered here as a single device, the signal source for which acts the outer space with its inherent useful signals and noises. Equivalent noise factor of the active non-resonant antenna shows how much power to the ambient noise adds an active antenna, or a relative deterioration of the signal to noise ratio after the reception of the active antenna as compared with that attitude in the place of reception. Convenience of the proposed parameters is that they allow a pragmatic assess the suitability of an active antenna for use in concrete or projected noise environment, ie rational from an economic point of view, without undue overstatement to form requirements for its noise parameters. In addition, for practical assessment of the noise factor of the active antenna is sufficient to estimate or measure only the level of its own and external noise at the output of the antenna. The article also carried out adapting well-known formula relating the dynamic range of an active antenna to block by 3 dB with 1 dB compression point, the defining characteristics of this range based on the approach to the active antenna as a single unit in the HF band. To verify the validity and feasibility of options « effective radio-noise field intensity property » and «equivalent noise factor» experimental study of small round receiving one-turn loop antenna nonresonant HF band with an amplifier, integrated in the frame construction. The experimental data confirm the validity of the theoretical analysis. The article includes 4 figures, 1 table and references to 16 information sources.