EM Principles in RADAR
a system for detecting the presence, direction, distance, and speed of aircraft, ships, and other objects, by sending out pulses of high-frequency electromagnetic waves that are reflected off the object back to the source.
RADAR
the distance a pulse travels in space or the time it takes for a pulse to be transmitted
Pulse Length
a bowl-shaped antenna that uses a curved reflector to focus radio waves into a narrow beam, or receive radio waves from a specific direction
Parabolic
a device that emits a continuous signal at a fixed frequency and amplitude
+ Function:
Continuous Wave
Speed of Object
When electromagnetic waves hit an object (target). Some of this energy reflects back toward the radar. This principle enables radar to detect the presence of objects.
Reflection / Scattering
the time interval between pulses
Pulse Repetition Interval
an antenna that uses electronics to steer its beam in space
Electronically Scanned Array
a device that emits short pulses of energy, such as ultrasound or light
Pulsed Wave
If a target is moving, the frequency of the reflected wave changes (shifts). Radar uses this shift to determine the velocity of the target.
Doppler Effect
the number of pulses that occur within a specific time interval (usually per second)
Pulse Repetition Frequency
a group of antennas that work together to create a single, directional beam of radio waves
Phased array
the frequency of a wave appears different depending on the relative motion between the source and the receiver
Pulsed Doppler
The orientation of the electric field in the wave affects how it interacts with targets and can be used to distinguish between different materials or target shapes.
Types: Linear, Circular, Elliptical
Polarization
smallest unit in radar imaging where two targets can't be distinguished unless they have different Doppler shifts
Resolution Cell
a flat, two-dimensional arrangement of multiple antenna elements, where the elements are positioned on a plane, allowing for the radiation pattern to be steered in both the horizontal and vertical directions by adjusting the phase of the signal fed to each element
Planar array
Focuses on one-way communication to a large audience or detection of objects (in radar)
Primarily used for broadcasting signals
Common ranges include:
Radio
Electromagnetic waves lose energy as they propagate due to absorption and scattering in the atmosphere. Radar systems must account for this loss to ensure accurate detection
Attenuation
Length of a portion of beam where power is one-half peak transmitted power
RADAR Beam Width
a directional antenna that sends radio waves in a specific direction. It's made up of a driven element, a reflector, and one or more directors
Yagi-Uda
used to connect devices within a limited area to the internet
Wi-Fi