Extra exam question E9H02

WhyOn 160 and 80 meter receiving antennas, atmospheric noise is generally so high that directivity matters much more than losses. On 160 and 80 meters, atmospheric noise is generally so high that a receiving antenna's directivity, its ability to null out noise and interference from unwanted directions, matters far more than minimizing ordinary antenna or feed line losses, since a bit of extra loss barely affects the already noise-dominated signal-to-noise ratio, answer A. Good directivity doesn't require mounting the antenna a half wavelength up (many effective low-band receiving antennas are mounted quite low), and low-loss coax isn't essential the way directivity is, so "all these choices" overstates the requirements.