How to Calculate VHF Radio Antenna Length

In radio frequency (RF) terminology, the Very High Frequency (VHF) range is the signal spectrum from 30 to 300 megahertz (MHz). To receive a specific VHF signal, you simply need a dipole antenna. Comprised of two lengths of wire or other conductive metal, a dipole antenna's shape allows the incoming signal's electromagnetic field to induce an alternating current (AC) within the antenna's material. To ensure the best possible reception of a given frequency, the total length of the antenna must be equal to one-half of the signal's total wavelength.

Instructions

1. • 1

     Decide which frequency you want the antenna to receive. Express the frequency in megahertz (MHz).

   • 2

     Multiply this frequency by 1,000,000 to convert its units to hertz (Hz).

   • 3

     Divide 299,792,458 meters/second (m/s, the speed of light) by the frequency in hertz (Hz). This will give you the signal's wavelength in meters.

   • 4

     Divide this wavelength by 2. This result represents the combined length in meters of the entire dipole antenna.

   • 5

     Divide by 2. This is the length that each of arm of the antenna must be in order to properly receive the signal.