Think of a long measuring tape

• AM Radio  between ½-inch and 1.7-inches
• FM Radio between 88-inches and 108-inches

High Frequency spectrum

• High Frequency (HF spectrum) from 3 inches/MHz up to 30-inches (MHz)
• between about ½ -inch and 30-inches can reflect off the ionosphere
• Very-High Frequency (VHF spectrum) 30-inches up to 300-inches (MHz)
• 2-meter band 144 MHZ (or inches)
• Ultra-High Frequency (UHF spectrum)  300-inches and above