Radar Fundamentals Prof. Bierng-Chearl Ahn Director of Applied Electromagnetics Laboratory College of Electrical and Computer Engineering Chungbuk National University

CONTENTS 1. What is a Radar? 2. Radar Concept 3. Radar History 4. Radar Classification 5. Radar Design 6. Emerging Radar Technologies 7. Pulse Radar 8. Summary

1. What is a Radar? Radar Radio detection and ranging : objects detection, location and speed measurement Radar waves : ultrasonic, radio, infrared, laser Ladar : laser detection and ranging Sonar : sound detection and ranging Radar applications Military : target detection (land vehicle, aircraft, ship, projectiles, personnel), terrain imaging (SAR), tracking and targeting, fire control, land mine detection Civil : police speed gun, marine navigation, automobile anti-collision, liquid level measurement, industrial speed measurements, motion sensor, meterology(weather radar), remote sensing(earth monitoring, satellite radar), industrial imaging(cancer, concealed weapon, wood)

2. Radar Concept Radar Principle

3. Radar History Evolution of Radar Technology - 1886 : Heinrich Hertz`s demonstration of radiowave - 1920`s : Aircraft (bomber) detection and early warning - 1930`s : Bi-static CW(continuous wave) radar - 1940`s : Mono-static pulse radar - 1950`s : Pulsed Doppler radar and signal processing concept - 1960`s : Phased array radar - 1970`s : Digital MTI(moving target indicator) and imaging radar - 1980`s : SAR(synthetic aperture radar) and OTH(over-the-horizon) radar - 1990`s : Multifunction radar (Patriot Missile Defense Radar) - 2000`s : Space borne radar(SIR-E/SRTM) SRTM(Shuttle Radar Topography Mission) PESA(passive electronically scanned array): single source per radar AESA(active electronically scanned array): one source per an element

4. Radar Classification Radar Classification - Parameters and Functions - Range: short, medium, long range - Frequency: HF, UHF, L, S, C, X, Ku, Millimeter (‘radar bands’) - Function: surveillance, tracking, imaging - Information: 1d, 2d, 3d, 4d, image - Object: aircraft, ship, missile, vehicle, weather - Processing: MTI, pulse, Doppler, LPI, SAR - PRF: low, medium, high LPI(low probability of intercept) <Raytheon APG-27 AESA aircraft radar> <Bosch LPR3 77GHz car radar>

Size, Power, Reliability 5. Radar Design Radar Design Steps Mission Analysis Sensor Requirement Sensor Design System Parameters Weight, Volume, Size, Power, Reliability Subsystem/module Parts/ SW design Implementation • Environmental limits • Applicable technology & components limits • Radar frequency selection • Antenna selection: mechanical or electrical scanning • Choice of radiowave polalization • Radar waveform • Type of signal processing : MTI or pulse Doppler MTD • Transmitting power :Tube/MPM (microwave power module) or solid-state

6. Emerging Radar Technologies Trends in Radar Technology - Ultra-wideband radar - Laser radar, optical signal processing/photonics - Microwave and millimetric radiometry - SDR(software defined radar) - COTS(commercial off-the-shelf) Technologies - Radar networks - Computer modeling and simulation - Performance prediction of radar systems - Computer modeling for design - Scenario/engagement modeling for EW - New applications: landmine and underground objects, concealed weapon, vital signs, breast cancer

7. Pulse Radar(1) Structure of a Pulse Radar

7. Pulse Radar(2) Example of a Pulse Doppler Radar Samraksh BumbleBee Radar (Oct. 2008): velocity only, monitoring and classifying human activities, 10m range, USD 100/each, 5.8GHz, 40mW power consumption, for use with USN sensor node (Crossbow’s TelosB Motes), detects sub-centimeter displacement, 300 measurements per second

7. Pulse Radar(2) Example of a Pulse Doppler Radar M/A-COM Short Range Radar Sensor

7. Pulse Radar(2) Example of a Pulse Doppler Radar M/A-COM Short Range Radar Sensor

7. Pulse Radar(2) Example of a Pulse Doppler Radar Siemens VDO Blind Spot Detection Sensor

7. Pulse Radar(3) Radar Measurements - Range: measured by time of flight R = cτ/2 - Elevation and azimuth angles: measured by antenna beam pointing direction - Speed (= range rate): measured by Doppler frequency shift fd = 2v/λ = 2vf/c <Shuttle Topography Radar – Tutuila Island of American Samoa and Continental US>

7. Pulse Radar(4) Radar Range Equation SNR = 14.38 dB

7. Pulse Radar(5) Pulse Repetition Frequency Spectrum of Transmitted Signal

7. Pulse Radar(6) Range Resolution Angular Resolution ΔR = cTp/2 = c/(2 x BW) Angular Resolution Δθ = θ3dB Minimum Range (Blind Range) Rmin = cTp/2 Maximum Unambiguous Range Rmax = c/(2xPRF) Pulse Radar Bandwidth BW = 1/Tp

7. Pulse Radar(7) Radar Signal Processing Issues - Space-time adaptive processing - CFAR detection and clutter rejection - MTI/MTD - SAR/ISAR processing, high-resolution radar signal processing - Interferometric techniques - Target classification - Radar data fusion - Polarimetric techniques - Radar waveform design - Fusion with other sensors - Real-time digital signal processing

7. Pulse Radar(8) Applications of Pulse Radar - Military radars: search radar, tracking radar, artillery locating radar - Weather radar - Marine navigational radar - Industrial level meter - Aircraft altimeter - Automotive radar - Vital signs radar - Ground penetrating radar - Time domain impulse radar

8. Summary Radar Technology - Old and high technology - Constantly evolving - Many diverse applications Pulse Radar - Most prevalent and versatile - More complicated than CW types - Sophisticated signal processing