What Is RF?
RF stands for Radio frequency. All kind of Wireless technologies like radar, GPS, ham radio, cordless phones, televisions and radio broadcasts uses RF mode of communication. RF technology is used in cell phones, Bluetooth and remote control toys. We can say that Radio frequency waves are ubiquitous. RF waves travel at the speed of light which is 300,000 km/s. These are electromagnetic waves and have frequency lower than that of visible light due to which RF waves become invisible to human eye.
Cycles per second or Oscillations determine the frequency of RF waves. One cycle makes 1 Hertz; 1000 make 1 Kilohertz (KHz); 1 million make 1 Megahertz (MHz) and 1 billion cycles make 1 Gigahertz (GHz). For example, if we tune to AM 980, then the signal broadcasts at an oscillation of 980,000 times per second or we can say it has a frequency of 980 KHz. The RF range is divided among various parties and a part of it is licensed to them.
Federal Communications Commission (FCC) regulates all the RF waves in United States. For example, 49 MHz is the designated frequency of a baby monitor. Similarly, cordless phones and other mediums have different designated frequencies.
The National Telecommunications and Information Administration (NTIA) along with FCC also take part in determining RF allotment. Until now, frequencies ranging from 9 KHz – 275 GHz have been allocated according to FCC while highest bands are reserved for radio and satellite astronomy. Major categories with their RF ranges are shown below. Also there are no gaps between various categories because other frequencies are used for systems like alarm systems, garage door openers, emergency broadcasting and amateur radio etc.
Aeronautical/Maritime 9 KHz – 535 KHz
AM radio 535 KHz – 1,700 KHz
Shortwave radio 5.9 MHz – 26.9 MHz
Citizen’s Band (CB) 26.96 MHz – 27.41 MHz
TV stations 2-6 54 MHz – 88 MHz
FM radio 88 MHz – 108 MHz
TV stations 7-13 174 MHz – 220 MHz
Cell phones CDMA
824 MHz – 849 MHz
Cell phones GSM
869 MHz – 894 MHz
Air Traffic Control 960 MHz – 1,215 MHz
GPS 1,227 MHz – 1,575 MHz
Cell phones PCS
1,850 MHz – 1,990 MHz
According to the frequency of waves the RF table is divided and labeled. Extremely low frequency (ELF) has range 3-30 Hz while Extremely High Frequency (EHF) has range 30-300 GHz. Very high frequency (VHF) is used by televisions and radio stations 2-13 and Ultra High Frequency (EHF) is used by mobile phones, television stations and two-way radio waves. UHF and VHF are the waves with whom we are most familiar. Super High Frequency (SHF) is used in microwaves ovens to cook food. These are followed by visible light and infrared waves at higher frequencies. You may check FCC website for more information on Radio Frequency and its spectrums.
Category: Technology