The word ‘radio’ (radio device) is the first thing we know about radio communication. For some, radio communication is limited, and rightly so. Now Radio, a device that is used to listen to news, music, and other programs broadcasted from a distant location, using specific radio channels, is nowhere in sight. The technological advancements over the last two decades have given rise to smartphones and smart TVs (Televisions). But what about the technology behind the Radio devices? Is it still here? Pretty much so.
Radio devices worked on radio waves, catching Radio Frequency signals in the frequency range 87MHz- 108MHz for FM (Frequency Modulation) and 535 KHz-1.7MHz for AM (Amplitude Modulation). This Radio frequency range is categorized as the sub-GHz frequency range.
Radiofrequency is part of the huge electromagnetic spectrum and represents a small portion of the entire electromagnetic waves, between 3kHz- 300GHz. This frequency range is termed as radio frequency and all the RF communications that we see today utilize some portion of this radio frequency range.
What is Radio Frequency Communication?
Radiofrequency communication is simply defined as the use of radio frequency signals to communicate and transfer data, audio, fax, etc., from one device to another, from one place to another. At present, there are ample technologies that use Radio Frequency (RF) communication. For example- Wi-Fi, Bluetooth, NFC, RFID (Radio Frequency Identification), BLE, LoRa, Mobile communication based on cellular networks such as LTE, and other low power wide-area networks (LPWANs) such as Sigfox, Zigbee, NB-IoT, LTE-m, etc.
Radio Frequency communication is the backbone of many security establishments including armed forces. RF communication has been an integral part of the armed forces for decades and still continues to be in the form of walkie-talkies, transceivers, GPS, and marine and aviation radios.
Radiofrequency communication is divided into several categories based on the radio frequency spectrum and the operating frequencies being used.
Let’s some of the prominent categories of radio communication:
Types of Radio Communication: Frequency
Based on the radio frequency, radio frequency communication technologies are categorized as follows:
Below 1 GHz (<1 GHz)
Below 1 GHz RF band was quite popular just two decades ago and it still is. The most prominent ISM (Industrial, science, and medical) bands were first established at the International Telecommunications Conference hosted by the ITU (International Telecommunication Union) in 1947, Atlantic City.
The ISM frequency bands were designed for the “Operation of equipment or appliances designed to generate and use locally radio frequency energy for industrial, scientific, medical, domestic or similar purposes, excluding applications in the field of telecommunication” as per article 1.15 of the ITU regulations.
The ISM bands are generally open frequency bands that vary in different regions as permitted. However, at present ISM bands are not limited to below 1GHz but most RF technologies use the 2.4GHz band as well as the 5GHz band to avoid interference. The prominent FM and AM radio operate in the sub 1GHz band as I mentioned earlier. Radio Frequency Identification technology also uses the Low Frequency (LF, 128 kHz), High Frequency (HF, 13.56MHz), and Ultrahigh Frequency (UHF, 860 MHz-960 MHz)
1GHz- 5GHz
The 2.4 GHz ISM band is the most used radio frequency subcategory as various IoT technologies such as Wi-Fi, BLE, etc. work in the frequency range. ZigBee (IEEE 802.15.4) and Bluetooth (IEEE 802.15.1) also work using the 2.4 GHz frequency band. Cordless phones also use RF communication channels falling in the same RF band.
Apart from that, many household items such as Microwave ovens also use the microwave (5GHz) frequency for heating purposes.
5 GHz and 5 GHz+
Radiofrequency in this category is termed as microwave. As the frequency of radio signals increases the energy associated with the signals also increases (E=HV), thus the microwave frequency is high in energy but offers short-range communication due to low wavelength and low coverage.
The IEEE 802.11a and 802.11n wireless standards, both are 5G capable and used for 5G Wi-Fi, and IEEE 802.11ac is used for Wi-Fi, exclusively 5G, offering significant advantages over 2.4GHz Wi-Fi in terms of speed (up to 20 Gigabits per second), power consumption, range, etc.
Components of Radio Frequency Communication
When we talk about components that allow radio frequency communication, we think of how an RF signal travels and how it is received at another end after being transmitted from one end. The Radio Frequency signals are also converted, to and from, electrical signals to electromagnetic signals. The primary understanding is that communication is all about transmitting information/data from one place to another, from one device to another.
In the case of RFID, the communication between an RFID tag and an RFID reader is the best example to understand this. An RFID tag is a small electronic device that consists of a microchip to hold information and an antenna to capture interrogating RF signals coming from the RFID reader. The RFID tag antenna also modifies the signals from electromagnetic signals to electric signals and then again into electromagnetic signals. The same thing happens at the reader’s end. Some RFID readers come with an in-built antenna, known as integrated RFID Readers. Some require an antenna separately.
So, radio frequency communication requires the following components:
1. Phase-locked oscillators (PLO) to produce the RF signal at the required frequency.
2. Modulator to change the frequency, amplitude, or phase of an IF (Intermediate Frequency) carrier for information encoding.
3. Upconverter to shift the modulated IF signal to the RF signal.
4. Power amplifier to increase the power level of the modulated RF carrier.
5. TX antenna for transmitting the RF carrier in the direction of the receiver.
6. RX antenna to collect the transmitted RF signal at the receiver.
7. RF filter which allows only a specified range of RF frequencies to pass and blocks all other frequencies.
8. A low-noise amplifier (LNA) which amplifies the weak received RF carrier.
9. Mixer and IF amplifier to shift the RF carrier to a lower frequency below the RF band and to amplify it to a level where it can be demodulated.
10. Demodulator which removes the information from the low-frequency carrier.
At present various IoT devices depend on Radio Frequency communication and RF communication technology is playing a significant role in enabling the modern industrial revolution (Industry 4.0). Technologies like Wi-Fi, BLE, Bluetooth, RFID, NFC, and various LPWANs such as LoRaWAN, Sigfox, NB-IoT, LTE-m, etc. use RF communication to facilitate low power wide area IoT communication.
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