Cellphones use microwaves instead of radio waves because microwaves offer several advantages that make them more suitable for mobile communication:
Frequency and Bandwidth: Microwaves have higher frequencies than traditional radio waves. Cellphones typically operate in the microwave frequency range of several gigahertz (GHz), while traditional radio waves are in the range of megahertz (MHz). Higher frequencies allow for more data to be transmitted in a given time, providing higher bandwidth and faster data transfer rates.
Data Capacity: Microwaves can carry more data compared to radio waves due to their higher frequencies. As smartphones and other mobile devices have become more data-intensive, the need for higher data capacity has grown. Microwaves can accommodate this demand more effectively.
Antenna Size: The size of the antenna is inversely proportional to the wavelength of the signal. Since microwaves have shorter wavelengths than radio waves, the antennas used in cellphones can be much smaller, making mobile devices more compact and portable.
Line-of-Sight Communication: Microwaves are more direct and easily focused in a particular direction compared to radio waves. This characteristic is beneficial for point-to-point communication between cell towers and mobile devices.
Penetration and Interference: Microwaves are less prone to interference and can penetrate certain obstacles, such as buildings and foliage, more effectively than lower-frequency radio waves. This allows for better signal coverage in urban environments where buildings can obstruct radio signals.
Cellular Network Design: The use of microwaves enables the implementation of cellular network designs with smaller cells (microcells, picocells), which can handle higher user densities and offer better network capacity in crowded areas.
Regulatory Considerations: Governments and telecommunication authorities allocate specific frequency bands for different purposes. Microwaves are allocated for mobile communication due to their technical advantages and capacity to meet the demands of modern mobile networks.
Despite these advantages, cellphones and mobile networks still utilize a mix of different frequencies, including lower-frequency bands, to achieve a balance between coverage, capacity, and data transfer rates. Different frequency bands serve different purposes, such as providing wide-area coverage (lower frequencies) and offering high data capacity in densely populated areas (higher frequencies). This combination of frequency bands ensures efficient and reliable mobile communication.