Question T3B06
From subelement T3 - T3B
What is the formula for converting frequency to approximate wavelength in meters?
Why is this correct?
The correct formula is wavelength = 300 ÷ frequency (MHz). This comes from the speed of light (300,000,000 m/s) divided by frequency, simplified by using MHz instead of Hz. Choice A multiplies instead of divides. Choice B uses hertz instead of megahertz, requiring division by 300,000,000. Choice C has the formula inverted. Only D gives the proper relationship where higher frequencies yield shorter wavelengths.
Memory tip
Remember the inverse relationship: as one goes up, the other goes down. The number 300 is always the numerator (top) in wavelength calculations. If you see 300 in the denominator or being multiplied, it's wrong. This pattern applies to all frequency-to-wavelength conversions in amateur radio.
Learn more
This formula connects directly to antenna design and frequency privileges. A half-wave dipole for 146 MHz (2m band) calculates as 300÷146 = 2.05 meters, so the antenna is about 1 meter long. Understanding this relationship helps you determine proper antenna lengths for your frequency allocations and explains why we refer to amateur bands by wavelength (2m, 70cm) rather than just frequency.
Think about it
Why do you think amateur radio operators often refer to bands by wavelength (like '2 meters') instead of frequency when the formula shows they're mathematically related?