A microwave dish, commonly known as a microwave antenna or parabolic antenna, is a type of antenna used to transmit and receive microwave signals in various applications, such as satellite communications, wireless internet, and radar systems. The principle behind a microwave dish is based on the behavior of electromagnetic waves, specifically microwaves.
The key principle behind a microwave dish is called "reflection" or "focusing." The dish is designed in the shape of a paraboloid, which is a three-dimensional curve formed by rotating a parabola about its axis. This parabolic shape is crucial for directing the incoming or outgoing microwaves in a specific direction.
When a microwave signal is transmitted from a source (e.g., a satellite uplink), it is directed towards the microwave dish. As the signal encounters the dish's curved surface, the electromagnetic waves get reflected off the surface. Due to the parabolic shape, all the reflected waves converge at a single focal point, known as the "focus" of the dish.
In the case of receiving signals, the process is reversed. Incoming microwave signals from a specific direction (e.g., satellite downlink) arrive at the dish and get focused at the focal point.
The focal point is where the feed horn or feed element is positioned. The feed horn is a specialized device that collects or emits the microwaves at the focus. In transmitting antennas, the feed horn converts electrical signals from the transmitter into microwave radiation, which then gets reflected by the dish and sent out into space. In receiving antennas, the feed horn captures the incoming microwave signals and converts them into electrical signals that can be processed by the receiver equipment.
The use of a parabolic dish allows for highly focused and directed microwave beams, which enhances the antenna's performance in terms of gain (the antenna's ability to concentrate energy in a specific direction) and directivity (the ability to transmit or receive signals effectively in a particular direction).
It's important to note that the size of the dish is directly related to the frequency of the microwaves it operates with. Higher-frequency microwaves require smaller dishes, while lower-frequency microwaves necessitate larger dishes to achieve the same level of focusing and directivity.