Extra exam question E4C11

WhyInput attenuation reduces receiver overload on the lower HF bands with little impact on signal-to-noise ratio because atmospheric noise there is generally greater than the receiver's own internally generated noise, even after attenuation. On the lower HF bands, atmospheric noise picked up by the antenna is typically much stronger than the receiver's own internally generated noise, so adding input attenuation reduces both the signal and that dominant atmospheric noise by roughly the same amount, preserving the signal-to-noise ratio while cutting down the raw signal level enough to avoid overloading front-end circuitry, answer D. There's no low-pass filter boosting lower frequencies, no dedicated noise filter involved, and signal and noise aren't attenuated through some separate mechanism, they're reduced together by the same attenuator.