S/N performance of aperiodic monopoles

A short monopole connected to a high-impedance amplifier provides an output to field strength transfer function nearly independent of frequency over a wide band. Such antennas are advantageous for receiving at low frequencies where external noise greatly exceeds amplifier noise. An examination is made of
S/N
performance of these antennas for the HF band. The
S/N
degradation compared to an external noise limited system is 1 to 3 dB for a 2.5-dB noise figure amplifier and 2 to 5 dB for a 5-dB noise figure amplifier, over 3 to 30 mHz.