Radio astronomers are the physicists that study radio propagation, this study shows how radio waves move through surfaces and out in free space. This study in turn helps determine the system of practical radios that we use in our everyday lives. Their most common use is seen in communication technologies, like the use of telephones, mobiles or televisions.
Radio waves are a type of electromagnetic radiation (EM), even though they are a smaller part of the spectrum. They’re longer than infrared waves in the spectrum band. The electromagnetic spectrum is divided into seven main regions, such as the radio wave, infrared waves, gamma rays etc.
The frequency of radio waves ranges from 300 GHz to a lower value of 3 kHz, the lowest in the electromagnetic spectrum. While the wavelength goes from 1 millimetre to 100 kilometres, that is the highest in the spectrum.
The discovery and understanding of radio waves have made significant contributions to the field of physics. This technology has helped create all sorts of telecommunication technologies that have made a huge impact on our modern society.
When we talk about the different types of radio waves we are in essence talking about how there are different bands of the spectrum for radio waves. These vary on the basis of frequency range and wavelength range. These shall now be discussed in turn:
Low to medium frequencies
ELF waves have a frequency range of less than 3 kHz and a wavelength longer than 100 km, making it the one with the lowest frequency but the larger wavelength means it can penetrate through water and rocks. These waves help in communications via submarines or inside mines and caves.
While these can easily be produced through man-made sources to hold communication lines, one of its natural sources is lightning. The waves produced by lighting bounce back between earth and space and are often responsible for disturbing electrical power lines.
The next in the spectrum are LF and MF that range from 30 kHz to 3 MHz in frequency and 1 m to 1 km in wavelength. These are mainly used for marine and radio aviation as well as commercial radio.
The AM radio waves fall between 535 kilohertz to 1.7 megahertz, this shows the long-range they have which is ideal for use at night because it remains undisturbed by the ionosphere, although that might sometimes affect the quality of the sound produced. This happens when a huge disturbance such as a skyscraper comes in between the signal, creating the partial blockage.
Higher frequencies
The HF, VHF, and UHF bands fall under the high-frequency spectrum. These range from 3 MHz to 3 GHz in frequency range while the wavelength goes from 10 m to 1 m depending on the specific type
These are typically used as FMs that are frequency modulation. FMs carry or encode audios or data signals on the wave carriers. The amplitude of these waves remains at its maximum while the frequency can be varied as well as the magnitude, depending on the audio or data being signalled.
Fm waves remain undisturbed by environmental factors, unlike AM waves. The frequency remains undisturbed, unlike the amplitude. The receiving end of these waves often ignores the disturbances in the amplitude as long as the signal maintains the required threshold.
Shortwave radio
In the middle of the spectrum, the frequency of the HF band goes from 1.7 MHz to 30 MHz while the wavelength goes from 10 to 100 m. this range of the spectrum is then even further divided into segments which are then distributed among various broadcasting centres in the local area.
These can be used hundreds of miles away as the source waves bounce off the ionosphere and can be rebounded to hundreds of miles away from the original point of source.
Highest frequencies
The SHF and EHF belong to the highest frequency waves and are sometimes called to be a part of the microwave band. These waves try to surf through the air molecules that sometimes distort these waves with absorption that reduces their range and how they are applied.
These are sourced through dish antennas that are used for television signals, their short wavelengths travel through narrow beams. Even though these are short wavelengths, their high range bandwidth allows the possibility of communication between two certain fixed locations.
The SHF waves are much stronger than EHF because they are not disturned while travelling through the air. These work in short ranges, like our wifi, does or wireless Bluetooth. These can be used only in short ranges where there are fewer obstacles for them to bounce off of.