Frequency versus Wavelength

Frequency and wavelength are inseparably related to each other. As frequency increases, wavelength decreases and vice versa.

• Frequency: The rate at which a radio signal oscillates from positive to negative.

• Wavelength: The length of a complete cycle of the radio signal oscillation.

Wavelength is, of course, a length measurement, usually represented in metric (meters, centimeters, and so on). And frequency is a count of the number of waves occurring during a set time, usually per second. Cycles per second is represented as Hertz (Hz). The dimensions are important to note, because the physical properties of the wave define antenna, cable, and power requirements. Wavelength is critical for antenna design and selection.

Wi-Fi signals operating at a frequency of 2.4 GHz have an average wavelength of about 12 cm. Since the wavelength is so short, antennas can be physically very small. A common design for antennas is to make them 1/4 of a wavelength or less in length, which is barely more than an inch long. That’s why Wi-Fi antennas can perform so well even though they are physically very small. As a comparison, a car radio antenna is much longer to get a decent signal because FM radio signals are an average of 10 feet long.

Wavelength and antenna length go together. To oversimplify, the longer the antenna, the more of the signal it can grab out of the air. Also, antenna length should be in whole, halves, quarters, eighths, and so on of the intended wavelength for best signal reception. The highest reception qualities come from a full wavelength antenna.

Perform this simple math formula to find wavelength: 300 / frequency in megahertz. The answer will be the wavelength in meters. So, 300 / 2437 _ 0.12 meters or 12 cm.