The VHF band designated for aviation extends from 117.975 MHz to 137 MHz. This range was chosen because VHF frequencies propagate via a quasi-optical path, which means they travel in relatively straight lines from the antenna, following the Earth's curvature and the horizon. This is different from lower frequency bands (like the medium-wave band used by NDB beacons), which can propagate over much greater distances due to ground wave and sky wave effects.

When you select a frequency on your radio—say, 118.100 MHz—you are selecting one specific channel within this 117.975–137 MHz band. The channels are spaced 8.33 kHz apart, so the sequence goes:

118.000, 118.008, 118.017, 118.025, 118.033... and so on.

Not all combinations of the last three decimal places are used. Historically, only channels ending in .00, .05, .10, .15, etc., (the "round" decimals) were available. The 8.33 kHz scheme introduced additional channels with decimals ending in .02, .07, .12, .17, etc. Your aircraft's radio will automatically tune to the correct physical frequency based on the frequency you select. You do not need to understand the underlying mathematics; you simply need to transmit and read back the frequency correctly.