INTRODUCTION TO RADAR - eee.guc.edu.egeee.guc.edu.eg/Courses/Communications/COMM1007 Radar...

RADAR TECHNOLOGY. PROF. A.M.ALLAM

1/30/2016 LECTURES 1

INTRODUCTION TO RADAR

RDR .TCH


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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


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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:


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3. Advantages of radars 3. Advantages of radars

Wide coverage

Works in all weather

High accuracy

Three dimensions detection x

y

z


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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


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Picture: German Engagement Control-

Search- and Acquisition- Radar Set

„Wiesel ”

AN/MPQ 64 „Sentinel ”

( ©THALES) BOR-A 550

Examples of battlefield radars


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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


1/30/2016 LECTURES

Examples of old eastern radars

P-14

P-18

P-19

P-30

P- 40

P-15 P- 12


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


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.Measuring the range and direction4

•Simplified block diagram:


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.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


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•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


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


1/30/2016 LECTURES 15

INTRODUCTION TO RADAR - eee.guc.edu.egeee.guc.edu.eg/Courses/Communications/COMM1007 Radar...

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