(a) What is the shape of the radio waves from a satellite when they reach a dish antenna on the roof of a building? Explain.
(b) Explain what happens to these waves when they reach the dish.
(a) The shape of radio waves from a satellite when they reach a dish antenna on the roof of a building is a type of electromagnetic radiation known as a "spherical wave."
To understand this, imagine an invisible sphere expanding outward in all directions from the satellite. The radio waves are emitted from the satellite and propagate in a wave-like manner, radiating outwards like ripples on the surface of a pond when a stone is thrown in. As the radio waves travel through space, they spread out and form a spherical pattern, similar to how sound waves propagate in all directions from a source in three-dimensional space.
When these radio waves reach the dish antenna on the roof of a building, they carry information encoded from the satellite. The dish antenna is designed to capture and focus these spherical waves onto a specific point, known as the focal point. This focusing is achieved through the shape and curvature of the dish, which is usually parabolic or curved in nature. The shape of the dish allows for the radio waves to bounce off its surface and converge towards the focal point.
(b) As the radio waves reach the dish antenna, several important phenomena occur.
Firstly, the dish antenna captures the incoming radio waves and reflects them towards a specific point. This reflection is due to the curvature of the dish, which acts like a mirror, bouncing the waves to focus at the focal point.
Secondly, once the waves converge at the focal point, they are collected by a receiver located at that position. The receiver is responsible for converting the electromagnetic energy of the radio waves into an electrical signal that contains the information transmitted by the satellite. This signal can then be processed and decoded to retrieve the desired information, such as TV signals, internet data, or other forms of communication.
It is important to note that the dish antenna needs to be accurately aligned with the satellite to ensure proper reception. Any misalignment can disrupt the received signal, leading to a degraded or lost connection. Therefore, precise installation and alignment of the dish antenna are vital to maintain a strong and stable link to the satellite.