What is Radio Frequency?
RF is the lowest portion in the electromagnetic spectrum familiar as a medium of analog and modern digital wireless communication systems. It spreads in the range between 3 kHz and 300 GHz. All known transmission systems work in the RF spectrum range including analog radio, aircraft navigation, marine radio, amateur radio, TV broadcasting, mobile networks, and satellite systems. Let’s take a look at each of the RF sub-bands and the areas of RF spectrum uses.
Extremely Low Frequency (ELF)
Frequency starting from 3Hz to 3 kHz is known as extremely low frequency or ELF range in the electromagnetic spectrum. This range is highly vulnerable to disturbance and easily gets distorted by atmospheric changes. It is hard to design a system in this rage is challenging because the larger wavelengths required long antennas which are practically impossible to achieve. Scientists use this frequency band in seismic studies to understand natural activities in the earth’s atmosphere.
Very Low Frequency (VLF)
Very low frequency is the starting range of RF and practical radio transmission systems which span from 3 kHz to 30 kHz. However, the design and implementation of the antenna system are extremely complicated due to the wavelength. It has been used in submarines and still using in time radio station which synchronizes clock signals between two remote locations.
Low Frequency (LF)
Low frequency is in the range of 30 kHz to 300 kHz. One of the important properties of LF signals is that they will get reflected by the earth’s ionosphere and thus it is suitable for long-distance communication. Since it’s a long wavelength and less attenuation from big terrains like mountains, it is generally called ground waves.
Low-frequency signals are used by amateur radio operators; it is one of the most important sources of information transfer when another kind of communication sources fails during some situation like natural disasters. Other areas are military applications like submarines, RFID tags in near-field communication, and some low-frequency radio broadcasting.
Medium Frequency (MF)
Medium frequency was one of the most popular frequency bands since the beginning of wireless radio transmission in the early nineteenth century. MF operates in the range of 300 kHz to 3 MHz. The design of transmitters, receivers, and the antenna is relatively less complex than other high-frequency transmission bands. MF has been widely used in AM radio transmission, navigation systems for ships and aircraft, emergency distress signals, coast guards and other experimental applications.
High Frequency (HF)
High-frequency signals range between 3 MHz and 30 Mhz. This frequency band is also known as a short wave. It also gets reflected by the earth’s ionosphere and it is one of the suitable bands for long distance communication. The high-frequency band is mostly used by the aviation industry, near field communication (NFC), government systems, amateur radio operators, and weather broadcasting stations.
Very High Frequency (VHF)
Very high frequency is one of the most commonly used bands which has an operating range from 30 MHz to 300 MHz. VHF frequency is widely used in analog TV broadcasting since it started a few decades back. FM radio broadcasting from 88 MHz to 108 MHz operates in the VHF frequency band.
Air traffic controllers and airline pilots use frequencies between 118 MHz to 137 MHz to communicate. Another uses includes private and business radio station, medical equipment (magnetic resonance imaging), amateur radio, and military applications. It is usually affected by big terrains but is suitable for short-distance communication.
Ultra High Frequency (UHF)
Ultra high frequency is the most important frequency band for modern wireless communication systems. It begins from 300 MHz to 3 GHz and is highly complicated to design and implement the system. UHF has many sub-frequency bands, some are restricted and assigned only for particular applications. It is used in GPS navigation systems, satellites, pagers, Wi-Fi, Bluetooth, television broadcasting, and most importantly GSM, CDMA, and LTE mobile transmission.
Super High Frequency (SHF)
Super high frequency is in the range of 3 GHz to 30 GHz. It can only operate in a line of sight path since any obstruction between the transmitter and receiving station will break the communication. It is commonly used in point-to-point communication, satellite systems, digital TV broadcasting in the Ku band (DTH service – direct to home), Wi-Fi (5GHz channel), microwave ovens, and mobile networks. Waveguides are suitable between transmitter and antenna due to higher losses of usual RF cables. System design is extremely hard in the SHF band due to its smaller wavelength and complexity.
Extremely High Frequency (EHF)
The extremely high-frequency band is the highest in the RF frequency spectrum which ranges between 30 GHz and 300 GHz. EHF is only used in advanced communication systems due to its complex nature and line of sight requirement. EHF is used in radio astronomy and remote sensing (weather analysis). It is suggested to use high-speed internet systems like 5G technology for future transmission networks due to large bandwidth availability.
Find more about the Applications of Millimeter Waves
RF is a broad spectrum and many of its characteristics has not been experimented with yet. It has a lot of possibilities in medical applications like MRI technology (even up to 12 Tesla for medical research), seismography, and oceanic studies. RF transceivers are significant components in interplanetary missions such as the Mars exploration mission. Our future digital communication systems may rely on high-frequency bands of the RF spectrum since they can support higher bandwidth.