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Introduction to Radar Antennas

March 2023

Radar systems have a wide range of applications, including weather forecasting, traffic control, navigation, automotive systems, and aviation. In military and defense operations, a radar system can be used to detect, track, and identify objects in the air, on land, and at sea. In this post, we will briefly explain how radar systems work, as well as introduce the most common types of radar antenna.

The term “radar” is short for “radio detection and ranging.” A radar system uses electromagnetic waves to detect and locate objects in its vicinity. Via its antenna, the radar system emits a radio wave signal, which then reflects off objects within its path and returns to the radar system. The radar system can determine the location, speed, and other characteristics of the objects in its field of view by measuring the time it takes for the radio wave signal to return, determining the direction from which it came, as well as analyzing the frequency and phase of the signal.

Each type of radar antenna has its own unique design and functionality. Some of the most common types of radar antennas include parabolic antennas, phased array antennas, and horn antennas.

Radar Antenna | JEM Engineering Blog
The parabolic antenna is arguably the most popular type of radar antenna.

The parabolic antenna features a curved dish-shaped reflector and a small feed antenna located at the focus of the dish. The feed antenna transmits and receives signals, which are reflected by the dish and then focused into a narrow beam. The parabolic (or “dish”) antenna is used in a wide range of applications, including weather radar, air traffic control, and military surveillance.

Consisting of an array of individual radiating elements, the phased array antenna is another popular type of radar antenna.

Each of the phased array’s radiating elements can be independently controlled to transmit or receive signals. By adjusting the phase and amplitude of the signals emitted by each element, phased array antennas can steer their beam in different directions and shape the beam in various ways. This makes them particularly useful for applications like radar tracking and missile defense. In a previous post, we talk more about the AESA, a type of computer-controlled phased array in which the beam of radio waves can be electronically steered in different directions without physically moving the antenna.

The horn antenna is a comparatively simpler and more compact type of antenna that is also suitable for radar systems.

The horn antenna consists of a horn-shaped metallic structure that is connected to a waveguide, which guides the radar signal between the antenna and the radar system. The horn antenna is commonly used in radar altimeters, which measure the height of aircraft above the ground. The JEM-440 is an example of a simple horn antenna useful in signal collection and monitoring.

In addition to the three aforementioned types of radar antennas, there are also many other specialized antennas used in various radar applications. For example, planar antennas are often used in ground-penetrating radar systems. A type of planar antenna, the Vivaldi antenna is particularly useful where high bandwidths and directivity is required, making it ideal for both radar and wireless communications systems. Another antenna that is commonly used in radar systems is the log-periodic antenna. These antennas can come in portable forms and can operate over a wide range of frequencies.

When choosing a radar antenna, it is important to consider a number of factors.

It is important to consider 1) radar antenna’s operating frequency, 2) your desired beamwidth and gain, and 3) the size and weight constraints of the application. In general, larger antennas provide greater gain and better performance, but they may not be suitable for all applications.

In conclusion, radar antennas play a crucial role in the functioning of radar systems, allowing them to detect and track objects over long distances. With a wide variety of antenna types available, it is important to choose the right antenna for your specific application to ensure optimal performance.

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