(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 the radio waves from a satellite when they reach a dish antenna on the roof of a building is a type of electromagnetic wave called a parabolic wave. This wave is often referred to as a parabolic reflector or a parabolic antenna. The reason it is called "parabolic" is due to the shape of the antenna dish, which is curved like a parabola.
The parabolic shape of the antenna dish is designed to efficiently capture and focus the incoming radio waves. When the radio waves emitted by the satellite reach the dish, they hit the curved surface. Due to the shape of the dish, the waves bounce off its surface and converge at a focal point, similar to how a concave mirror reflects light to a focal point. This focal point is where the receiver or feed horn is located, which collects the concentrated electromagnetic waves.
(b) When the radio waves from a satellite reach the dish antenna, they undergo several important changes. First, as mentioned earlier, the waves are reflected by the curved surface of the dish. Because the dish is carefully designed to have the shape of a parabola, the waves are focused and redirected towards the focal point.
Once the waves reach the focal point, they are collected by the receiver or feed horn. The feed horn is positioned at the focal point, and its purpose is to capture the concentrated waves and guide them further into the system for amplification and processing.
From there, the captured waves are passed through the electronic components of the antenna system. These components, such as low-noise amplifiers and filters, work to boost the strength of the signal and remove any unwanted noise or interference.
Finally, the amplified waves are sent through the transmission line, usually a coaxial cable, to the receivers and electronic devices connected to the dish antenna. These receivers then demodulate the waves, extracting the original information or data transmitted by the satellite, which can include television signals, internet data, or other types of communication signals.
Overall, the dish antenna plays a crucial role in capturing, focusing, and transmitting the radio waves from a satellite, allowing us to receive and utilize the information being transmitted.