Post on 25-Apr-2019
RADAR TECHNOLOGY. PROF. A.M.ALLAM
2
RADIO DETECTION AND RANGING
. RADAR1
•Transmitting e.m.w through
the antenna
•A portion is reflected back by
the target
•Antenna collects the returned
energy and delivers it to the
receiver
•Receiver processes the signal to
detect the presence of the target
and extracts:
- location
- relative velocity
Transmission
Reception
RADAR
TARGET
x
y
z
RADAR TECHNOLOGY. PROF. A.M.ALLAM
4
Operational:
Civil radar missions:
Detection Location
Resolution Tracking
Military radar may have additional requirements:
Classification Recognition
Missile communications Electronic protection
Spectral
Choice of frequency band
Choice of antenna and transmitted power
Instantaneous bandwidth
Frequency diversity
Compatibility with other radar & EMC requirements
2. Radar operational & spectral requirements:
RADAR TECHNOLOGY. PROF. A.M.ALLAM
5
3. Advantages of radars 3. Advantages of radars
Wide coverage
Works in all weather
High accuracy
Three dimensions detection x
y
z
RADAR TECHNOLOGY. PROF. A.M.ALLAM
6
Examples of air defense radars
The Pilar Radar Station
AN/FPS-88 (Portugal(
AN/FPS-85 in Eglin Air
Force Base (Florida)
AN/TPS-75 search radar
with ULSA antenna, with
AN/TPS-43E antenna in
background
3D Radar System DR 174
EADS
AN/TPS-59
RADAR TECHNOLOGY. PROF. A.M.ALLAM
7
Picture: German Engagement Control-
Search- and Acquisition- Radar Set
„Wiesel ”
AN/MPQ 64 „Sentinel ”
( ©THALES) BOR-A 550
Examples of battlefield radars
RADAR TECHNOLOGY. PROF. A.M.ALLAM
8
SRE-M7, a typically en-
route radar made by the
German DASA company
The Air
Surveill
ance
Radar
ASR-12
Precision Approach
Radar PAR-80 made
by ITT
Surface
Movem
ent
Radar
ASDE
Microburst radar MBR
ALE 335 L ATC-antenna
fitted with ALE 9 beacon
Examples of ATC radars
RADAR TECHNOLOGY. PROF. A.M.ALLAM
1/30/2016 LECTURES
Examples of old eastern radars
P-14
P-18
P-19
P-30
P- 40
P-15 P- 12
RADAR TECHNOLOGY. PROF. A.M.ALLAM
AN/TPX-46(V) IFF interrogator
Cossor's Large Vertical Aperture SSR
antenna mounted above the array used in
the Raytheon ASR-10 SS surveillance radar
Antenna of the interrogator NRS-12
Messenger SSR System
(The S-1095 antenna on a marconi-tower )
Examples of IFF radars
RADAR TECHNOLOGY. PROF. A.M.ALLAM
12
.Measuring the range and direction4
where:
•T is the Pulse Repetition Time (T=1/PRF), is time from beginning of one
pulse to the beginning of the next
•δ is length or duration or pulse width of a given pulse
•PRF is frequency at which consecutive pulses are transmitted
The pulse duration or width controls the minimum range (dead zone) because the
receiver in pulse radar is off while transmitting the pulse:
Rmin = C x δ / 2
•The direction: is determined from the direction of arrival of the reflected signal
which need very narrow beam of the radar antenna
R = C x ∆T / 2
Rmax = C / (2 x PRF)
PRF = 1 / T
T
∆T
δ Echo
t
•The range:
Is the ratio of the average TX power to the peak TX power ( also is the ratio of the
pulse width to the PRP (dt=δ/T)
•Duty cycle (factor)
•Pulse energy PE=Ppk x δ
RADAR TECHNOLOGY. PROF. A.M.ALLAM
1/30/2016 13
•Range resolution and range bin
Range resolution-
Is a radar metric ΔR that describes its ability to detect targets in close proximity to each other as
distinct objects
Targets within the same range bin
can be resolved in cross range
(azimuth) utilizing signal
processing techniques
M=(Rmax –Rmin)/
ΔR
Let us divide the distance between Rmax ,
Rmin into range bins (gates), each of
width ΔR
ΔR =R2 – R1= c(t2 – t1)/2 = c td / 2
Consider two targets located at ranges R1, R2, corresponding to time delays t1, t2 and denote the
difference between those two ranges as ΔR, then
Targets separated by at least ΔR
will be completely resolved in range
what is the minimum ΔR ?
ΔRmin =c δ / 2
RADAR TECHNOLOGY. PROF. A.M.ALLAM
1/30/2016 LECTURES 14
Example 1:
The time between the transmission and reception of the pulse is 300µsec.
determine the range of the target?
R= C ∆T/2 = 3x108x300x10-6 /2 = 45000 m = 45 km = 45/1.85 = 24.32 nm
Example 2:
Calculate the max. range of a radar has PRF 500 pps?
Rmax = CxT/2 =C/(2xPRF) = 3x108/(2x500) = 300000 m = 300 km
= 162.162 nm
Example 3:
Calculate the max permissible PRF of a radar required to give a range of
200 nm?
Rmax = C/(2xPRF)
PRF = C/( 2XRmax) = 3x108 / 2x200x1.85x1000) = 405 pps