It is always intriguing to learn about new technologies and how they work. In this guide, we will be talking about radar technology and how it works. If you would like to know what this technology is about, you should read through this guide with zest.
What is radar?
RADAR stands for ‘Radio Detection and Ranging’ and is an active transmission and reception method in the microwave GHz range. Radar sensors are used for contactless detection, tracking, and positioning of one or more objects by means of electromagnetic waves.
How does RADAR work?
The basic working principle of all the radio systems is the same. The radio uses a transmitter to produce an electromagnetic signal that is then propagated into space using an antenna. When this signal strikes an object, it gets reflected back, and this reflected signal is known to be the echo signal.
When the antenna detects the echo signal, it gets fed into the receiver. The receiver then processes the echoed signal to get useful data out of it. The output from the receiver is then passed to the Threshold decision system. Here, the output is compared with a threshold; if the output is below the threshold, the signal is considered a noise signal.
For finding the range of the object, the system uses the time taken by the signal to get reflected. For the target location, an angle is calculated from the direction of the echo signal to the direction where the antenna is pointing. For moving objects, the Doppler Effect is used to calculate the speed and range.
Types of radar systems
Bistatic radar is a radar system that comprises a transmitter and a receiver that are separated by a distance that is equal to the distance of the expected target. A radar in which the transmitter and the receiver are located at the same place is known as a monastic radar. Most long-range surface-to-air and air-to-air missiles employ the use of bistatic radar.
A continuous-wave radar is a type of radar where a known stable frequency continuous wave radio energy is transmitted and then received from any of the objects that reflect the waves. A continuous-wave radar uses Doppler technology which means the radar will be immune to any form of interference by large objects that are stationary or slow-moving.
A Doppler radar is a special form of radar that employs the use of the Doppler Effect to produce velocity data about an object at a given distance. This is achieved by sending electromagnetic signals towards a target and then analyzing how the object’s motion has affected the frequency of the returned signal. This variation has the capacity to give extremely accurate measurements of the radial component of a target’s velocity in relation to the radar. Doppler radars have applications in different industries including aviation, meteorology, healthcare, and many others.
Monopulse radar is a radar system that compares the received signal from a single radar pulse against itself with an aim of comparing the signal as seen in multiple polarizations or directions. The most common form of monopulse radar is the adaptation of conical scanning radar which compares the return from two directions to directly measure the location of the target. It is important to note that most of the radars that were designed since the 1960s are monopulse radars.
A passive radar system is a type of radar that is designed to detect and track objects by processing reflections from non-cooperative sources of illumination in the environment. These sources include such things as communications signals and commercial broadcasts. Passive radar can be categorized in the same class of radar as bistatic radar.
Instrumentation radars are radars that are designed to test rockets, missiles, aircraft, and ammunitions on government and private test ranges. They provide a variety of information including space, position, and time both in real-time and in the post-processing analysis.
Weather radars are radar systems that are used for weather sensing and detection. This radar uses radio waves along with horizontal or circular polarization. The frequency selection of weather radar depends on a performance compromise between precipitation refection and attenuation as a result of atmospheric water vapor. Some weather radars are designed to use Doppler shifts to measure the speed of wind and dual-polarization to identify precipitation types.
Mapping radars are used to scan a large geographical region for geography and remote sensing applications. Because of their use of synthetic aperture radar, they are limited to relatively static objects. There are some specific radar systems that can sense humans behind walls thanks to the reflective characteristics of humans that are more diverse than the ones found in construction materials.
Navigational radars are generally the same as search radars. However, they come with much shorter wavelengths that are capable of reflecting from the earth and from stones. They are most common on commercial ships and other long-distance commercial aircraft. There are various navigational radars including marine radars commonly mounted on ships for collision avoidance and navigational purposes.
Fundamentals of Radar
The RADAR system generally consists of a transmitter that produces an electromagnetic signal which is radiated into space by an antenna. When this signal strikes an object, it gets reflected or reradiated in many directions. This reflected or echo signal is received by the radar antenna which delivers it to the receiver, where it is processed to determine the geographical statistics of the object.
The range is determined by calculating the time taken by the signal to travel from the RADAR to the target and back. The target’s location is measured in angle, from the direction of the maximum amplitude echo signal, the antenna points to. To measure the range and location of moving objects, the Doppler Effect is used.
The essential parts of this system include the following.
- A Transmitter: It can be a power amplifier like a Klystron, Travelling Wave Tube, or a power Oscillator like a Magnetron. The signal is first generated using a waveform generator and then amplified in the power amplifier.
- Waveguides: The waveguides are transmission lines for the transmission of the RADAR signals.
- Antenna: The antenna used can be a parabolic reflector, planar array, or electronically steered phased array.
- Duplexer: A duplexer allows the antenna to be used as a transmitter or a receiver. It can be a gaseous device that would produce a short circuit at the input to the receiver when the transmitter is working.
- Receiver: It can be a superheterodyne receiver or any other receiver which consists of a processor to process the signal and detect it.
- Threshold Decision: The output of the receiver is compared with a threshold to detect the presence of any object. If the output is below any threshold, the presence of noise is assumed.
Applications of Radar Technology
The applications of radar include the following.
It has 3 major applications in the Military:
- In air defense, it is used for target detection, target recognition, and weapon control (directing the weapon to the tracked targets).
- In a missile system to guide the weapon.
- Identifying enemy locations on the map.
Air Traffic Control
It has 3 major applications in Air Traffic control:
- To control air traffic near airports. The Air Surveillance RADAR is used to detect and display the aircraft’s position in the airport terminals.
- To guide the aircraft to land in bad weather using Precision Approach RADAR.
- To scan the airport surface for aircraft and ground vehicle positions
It can be used for observing or observing planetary positions and monitoring sea ice to ensure a smooth route for ships.
Ground Traffic Control
It can also be used by traffic police to determine the speed of the vehicle, and control the movement of vehicles by giving warnings about the presence of other vehicles or any other obstacles behind them.
Advantages of RADAR
- RADAR can penetrate mediums such as clouds, fogs, mist, and snow. The signals used by RADAR technology are not limited or hindered by snow, clouds, or fog. This means that even in the presence of these adverse conditions, data will still be collected.
- RADAR signal can penetrate insulators. Materials that are considered insulators such as rubber and plastic do not hinder RADAR signals from collecting data. The signals will penetrate the materials and capture the necessary data required.
- It can give the exact position of an object. RADAR systems employ the use of electromagnetic to calculate the distance of an object and its exact position on the earth’s surface or space.
- It can determine the velocity of a target. RADAR systems have the capability of calculating the velocity of an object in motion. Besides knowing its location, you will also have data regarding the velocity of the object.
- It can measure the distance of an object. RADAR systems work by measuring the exact distance of an object from the transmitter.
- It can tell the difference between stationary and moving targets. The data collected by RADAR systems is enough to tell whether the object was in motion or it was stationary.
- RADAR signals do not require a medium of transportation. RADAR employs the use of radio signals that can travel in air or space. They do not require any medium to be transported.
- RADAR signals can target several objects simultaneously. The radio signals used by RADAR operate on a wider area and can target more than one object and return data regarding all the objects targeted.
- It allows for 3D Imaging based on the various angles of return. The data captured by RADAR systems can be used to map an area and provide 3D images of the area based on the varying angles of return.
- It is wireless and does not rely on wire connectivity. Radio signals do not require a medium to travel therefore there is no need for wire connectivity.
- It is cheaper compared to other systems. RADAR systems are relatively cheaper especially if used for large-scale projects.
- High operating frequency allows for the storage of large amounts of data. The RADAR systems can store large amounts of information that can be used for more than one purpose.
- It covers a wider geographical area. The radio signals emitted by RADAR systems cover a significantly large geographical area at once.
Radar technology has improved various sectors in our world today. Interestingly, it keeps getting better, so we hope to see greater improvements in the coming years.