Question T3B05
From subelement T3 - T3B
What is the relationship between wavelength and frequency?
Why is this correct?
Wavelength and frequency have an inverse relationship - as one increases, the other decreases. This is because all radio waves travel at the constant speed of light (300 million meters per second). Since speed = frequency × wavelength, when frequency goes up, wavelength must go down to keep the speed constant. For example, the 2-meter band at 144 MHz has twice the frequency and half the wavelength of a 72 MHz signal. The formula wavelength = 300/frequency in MHz demonstrates this inverse relationship clearly.
Memory tip
Remember the seesaw principle: frequency and wavelength are always on opposite ends. When studying band plans, notice how higher frequency bands (like 70cm at 440 MHz) have shorter wavelengths than lower frequency bands (like 2m at 144 MHz). This pattern appears throughout the amateur spectrum.
Learn more
This inverse relationship directly affects antenna design and propagation characteristics. Higher frequency bands like UHF require shorter antennas due to their shorter wavelengths, while HF bands need longer antennas. The relationship also explains why HF signals with longer wavelengths can bend around obstacles and reflect off the ionosphere more effectively than VHF/UHF signals with shorter wavelengths, which tend to travel in straight lines.
Think about it
Why do you think amateur radio bands are often named after their approximate wavelengths (like '2-meter band' or '70-centimeter band') rather than their frequencies?