What would be the best frequency choice for communicating with a shore station 75 miles away during mid-day?

The best choice for communicating with a shore station 75 miles away during mid-day is the MF frequency band. MF, or Medium Frequency, is known for its ability to support long-distance communication, especially during the daytime when ionospheric conditions favor these frequencies.

During the day, higher frequency bands, such as VHF and even HF, experience changes in propagation characteristics due to solar radiation and daytime ionospheric behavior. VHF-FM mainly operates at frequencies from 30 to 300 MHz, which typically communicate well over shorter distances due to line-of-sight limitations and may not reach 75 miles effectively during mid-day.

The 22 MHz and 16 MHz bands are part of the High Frequency (HF) spectrum, and while HF can also handle long-distance communications, they may be subject to varying propagation conditions during the day that could hinder the reliability of the signal over 75 miles. The MF band, on the other hand, can provide consistent and reliable coverage for distances such as 75 miles due to its efficient groundwave propagation during the daytime.

Therefore, choosing MF as the frequency ensures a more reliable means of communication with the shore station at the specified distance and time.