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Printed & published by Dr Mohinder Singh, Director, DESIDOC, on behalf of DRDO.

RNI No. 55787/93

Readers of Technology Focus are invited to send their communications to the Editor, Technology FocusDESIDOC, Metcalfe House, Delhi - 110 054. India

Telephone: 011-23819975; Fax: 011-23819151; Drona-mail: publication@desidoc.deldom

E-mail: dirdesidoc@vsnl.net, dirdesidoc@drdo.org Internet: http://www.drdo.org/pub/index.shtml; http://www.drdo.com/pub/index.shtml

Technology Focus highlights the technological developments in DRDO, and also covers the products, processes and

technologies.

Dr Mohinder Singh, Director, DESIDOC, Metcalfe House, Delhi

Shri Ajai Kumar, Director of Aeronautics, Sena Bhavan, New Delhi

Dr Harihar Singh, Director of Armaments, Sena Bhavan, New Delhi

Dr JP Agrawal, Director of Materials, Sena Bhavan, New Delhi

Shri A Bhagavathi Rao, Director of Electronics, Sena Bhavan, New Delhi

Shri Gopal Bhushan, SO to SA to RM, South Block, New Delhi

Editors Assistant Editor Design & Pre-press Printing

Ashok Kumar, Vinod Kumari Manoj Kumar Rajesh Kumar JV Ramakrishna, SK Tyagi

Editorial Committee

Editorial Staff

Coordinator

Members

ground in the normal free state mode and has the facility to

mechanically lock at different elevated positions. The

platform also has provision for anchoring radar vehicle

(wheeled/tracked).

Four columns made of large diameter hollow cylindrical

tubes with natural ventilation and staircase for periodical

maintenance supports the platform. The landing at the top of

the platform is fenced in addition to the fencing of the

platform. Lightning arrestors have been provided for entire

platform and radar mounted vehicle. An external staircase

and lift have been provided for smooth movement of

equipment, materials and men. A power/manually operated

hoist has also been provided at the top of the platform to

position the test systems. Power and water required for the

test facility have been provided at the top of the platform

itself. A standby power supply ensures 100 per cent power

availability to the test platform.

This platform is first of its kind in the country and Asia.

Radar test platform

Vol. 11 No. 3 June 2003 ISSN : 0971-4413

BULLETIN OF DEFENCE RESEARCH & DEVELOPMENT ORGANISATION

RADAR TECHNOLOGY

June 2003 7362

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forces because of their rugged and compact structure,

high radiation efficiency, and high power handling

capabilities.

DRDO has achieved expertise and core

competence in design, development and fabrication of

slotted waveguide array antenna, which offers ultra

low side lobes for any frequency band. The

electromagnetic modelling technique has been used

to overcome the complex design problems. Several

software packages, viz., COBRAS, COBRAS DC,

COBICS, COBICSNO, LADSOFF, and ANSA with

copyright have been developed for slot characterisation,

linear array design, and array analysis. CAD-based slots

machining and specialised manufacturing technologies

have also been developed.

The antenna has built-in IFF (identification, friend or

foe) facility that uses array of dipoles fed with stripline monopulse comparator and guard channel. It

is being used in major DRDO projects like Tejas (LCA) multimode radar, multibeam surveillance

radar, maritime patrol radar for Naval advanced light helicopter, and battlefield surveillance radar.

Microstrip antenna—a printed dipole antenna—for active phased array radiating elements

and man-portable BFSR–SR (battlefield surveillance radar–short range), has been successfully

developed and integrated. The antenna has wide band and wide scan features. The printed dipole

structure has been designed with bent arms, an integrated balun, and a wide band microstrip

matching circuitry. The optimised structure, developed with extensive EM simulation, offers a wide

bandwidth in H plane, and good pattern characteristics with low cross-polarisation levels.

DRDO has developed a 64-element

(16 x 4) active phased array, using printed

dipole-radiating elements, which has

exce l l en t r ad ia t i on pe r f o rmance

characteristics with low side lobe patterns, o

and + 60 wide scan angle capability from

the broadside of the array.

A 512-element microstrip antenna

array in X band that meets the high

performance requirements of a BFSR–SR

search radar, has also been developed. The

array uses inset fed square patch elements

Microstrip Antenna

June 2003

Radar Technology

Tejas antenna–front view

E lectronic sensors play a vital part in

enabling armed forces to gather the

information about the enemy. Of all these

sensors, radar is the most important. Radar is in

use since the start of the Second World War,

when the continuous watch over the air and sea

approaches to Britain helped the Royal Air

Force to defeat the Luftwaffe in the Battle of

Britain. Since then the military uses of radar

have increased manifold. It is now being used

for such diverse military applications as

surveillance of large regions and early warning

of approaching ships, aircraft, and missiles; fire

control for automatically directing gunfire,

guiding missiles against air or surface targets;

artillery location of enemy, directing gunfire at

enemy aircraft from aboard radar-equipped

interceptor aircraft; radar bombsights; and

detection of submarines from aircraft.

Besides military applications, the radar is

used to measure distances and map

geographical areas and to navigate and fix

positions at sea. Meteorologist use radar for

short-term weather forecasting and to watch for

severe weather such as thunderstorms and

tornado. Commercial airlines are equipped with

radar devices that warn of obstacles and give

Slotted Waveguide Array Antenna

The slotted waveguide array antennas

are used in high-speed aircraft and

missile seeker-head where low

profile or lightweight installations

are required. High gain,

broadband operation, two-plane

monopulse and lightweight

features have made these

antennas very useful for airborne

applications. The mechanically scanned slotted waveguide array antennas are the workhorse

radiators for tactical aircraft radar and missile systems in most of the modern defence

Microwave Antenna Systems

accurate altitude readings. The radar-assisted

ground-controlled approach systems at airports

help planes to land in fog. It is also being used

by police to measure the speed of automobiles.

The key to the successful development

of radar systems for many of the applications

lies in harnessing the basic technologies

involved in the modern radar system designs.

Component technologies such as microwave

tubes, VLSI (very large scale integration)-

based ASIC (application specific integrated

circuit) chips, electronically controlled phase

shifters, dedicated signal processing (DSP)

chips display, and a host of microwave

components form the crucial technologies

needed for the sophisticated modern radar

system development.

DRDO has acquired the expertise of

designing, testing and evaluation of radar

systems using these crux technologies and has

translated them into major state-of-the-art radar

systems. A number of subsystem level

technologies needed for building the most

modern state-of-the-art radar systems for

military applications have been successfully

developed. Some of these key technologies are

described in this issue.

Microstrip antenna for BFSR–SR

Slotted waveguide array antenna

June 2003June 2003 54

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distributed on a small size aperture, and low-loss corporate feed network—the network designed

for a low side lobe Taylor's amplitude distribution. The antenna with backup structure weighs only

1.2 kg.

The active phased

array radar is being used

in ground-based, ship-

borne and airborne

platforms for long

range surveillance

and tracking. The active

phased array technology

overcomes inefficiencies like losses in power dividing/combing field network of conventional

passive phased array, and improves reliability using

transmitter/receiver (T/R) microwave modules. The

technology also significantly improves power efficiency,

low side lobes, and adaptive null placement to counter

jamming.

DRDO has developed the microwave T/R module

element for active phased array using indigenous

technology. The T/R module uses a hybrid microwave

in te gr at ed circuit (MIC) and monolithic microwave integrated circuit

(MMIC) for transmit and receive chains. Both transmit and receive chains are super-

components on two soft ceramic microwave laminates packaged compactly in a

single housing.

Salient Features

High peak power output with a large pulse width and duty over a large RF bandwidth

500 W peak transmit power output in L band

4.5 dB low noise figure over the frequency band

Receive gain : ≥ 35 dB

Receive attenuation : 6-bit

Shared phase shifter : 6-bit

Wide band printed dipole radiator

Distributed beam steering controller

Low loss RF manifold

Thermal management by cold plate technique

Distributed high efficiency flat profile power supplies

Modular concept, extendable to large aperture active arrays

Active Phased Array

Radar TechnologyRadar Technology

T/R module. 64-element array (below left)

Rajendra phased array assembly

Multifunction Phased Array Radar

Multifunction radar is the main

sensor for modern weapon control

systems. The radar consists of

electronic beam steering phased array

antennas and performs surveillance,

designation and tracking of multiple

targets, and simultaneous tracking and

guiding of multiple missiles. It provides a

cost effective sensor solution for

integrated weapons control.

DRDO has developed a multi-

funct ion radar Rajendra us ing

indigenous phased array technology for

3-D target detection, multitarget tracking

and multiple missile guidance under extreme hostile EW environment. A main phased array

consisting of 4000 phase control modules (PCMs), and a command phased array consisting of

1000 PCMs have been built to achieve the multi-functionality. A powerful high-end computer

computes phases for all the elements of the array.

Rajendra is packaged in two tracked vehicles: one for complete electronics and the other for

the command centre and the radar data utilisation station. A dedicated beam 'dwells' is used for

maintenance of tracks. The radar has the capability to maintain 20 automatically selected tracks

during pre-engagement phase, and multiple missiles and the assigned multiple aircraft tracks

during engagement phase with higher rate of updates for high accuracy for better target

neutralisation. The radar is highly mobile with fast deploying ability and automated operations. The

major functions of the radar are:

Surveillance of the assigned volume of space

Acquisition of aircraft targets either independently or handed over from group control

centre and battery surveillance radar

Tracking of targets

Tracking of assigned targets and missiles during engagement

Command guidance of missiles

Integrated IFF functions

Microwave phase shifter is the vital component for electronic beam steerable phased array

antenna. The antenna provides the radar excellent beam agility due to its inertia-less scanning at

adaptable and high scan rates. Among the phase shifters, the ferrite phase shifters are the most

Phase Control Modules

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7

Radar TechnologyRadar Technology

High Power Radar Transmitter

power supplies were evolved over long years of working on high voltage power supplies of various

voltage and power levels.

DRDO has developed a technology to build high average power transmitter and expertise in

the weight reduction techniques for minimising the weight and volume of transmitters essential for

airborne application. Indigenous development of transmitters and their integration in the radar have

been completed successfully for Indra I and Indra PC. Both have been inducted into the Services.

Transmitters for Rajendra phased array radar both for search and track, command guidance and

3-D central acquisition radar (CAR) are other major successful developments. The S band 7 kW

transmitter for airborne surveillance platform is another milestone representing a quantum jump in

average power.

DRDO has developed radar sources for stable

and coherent ultra low phase noise exciter signals for

the radar transmitter, local oscillator signals for the

radar receiver, a large agility bandwidth (>10 per

cent), fast multiple channel switching capability for

effective ECCM, wide band radar waveform

generation (linear FM or digital long length phase

codes), and a high order of spurious/harmonic

rejection. High spectral purity outputs and

improvement in vibration isolation for airborne radar

have been achieved using direct and indirect

frequency synthesis (utilising low noise phased locked

loop schemes), and SC-cut crystal resonators (in lieu

of AT cut type) as the basic reference sources in the frequency synthesisers.

The modern radar receivers are designed to generate ultra low internal noise, achieve

required front-end gain, phase and amplitude stability, high dynamic range, wide band tuning

capability, and protection against saturation

and burnout from nearby interfering radar

transmitters. In addition, multichannel receivers

are required for monopulse tracking and height-

finding 3-D surveillance radar. DRDO has

developed radar receiver technology using

state-of-the-art double superheterodyne

techniques offering features like pulse

compression (digital as well as analog), wide

front-end radar bandwidth with ultra low noise

figures, dual channel monopulse, large

Radar Sources & Receivers

Radar source for Indra

Dual channel radar receiver for Rajendra

rugged and are being used in indigenous radar systems. DRDO has

developed the phase control modules (PCM) in C and X band in

collaboration with IIT, Delhi and CEL, Sahibabad. The PCM

comprises radiating and pickup element, and the phase

shifter with digital driver. It is basically a non-reciprocal

analog phase shifter, but ingeniously converted to a

reciprocal digital phase shifter.

Salient Features

Specifications C band X band

Power 12 W average, 200 W peak 7 W average, 140 W peak

Insertion loss < 1 dB < 1 dBo o

RMS phase setting error 6 < 6

VSWR 1:1.5 1:1.5

Number of bits 5 bits serial data 5 bits serial datao o o o

Operating temperature 0 C to +55 C 0 C to +55 C

Weight < 100 g < 24 g

Type Dual mode ferrite reciprocal Dual mode ferrite reciprocal

Digital driver logic CMOS CMOS

DRDO has designed and developed several radar transmitters

using master oscillator power amplifier (MOPA) configuration and the

microwave power tubes such as klystrons, travelling wave tubes and

cross-field amplifiers. The technology to realise the peak power levels

in excess of 150 kW at an average power level of the order of 400 W to

7000 W has been well established and proven. The microwave

frequency bands involved are spanning L band to X band. The

technology to build a high average power transmitter for an airborne

application has also been achieved.

The key technology areas of design and development include high voltage power supplies (up

to 45 kV/10 kW) having pulse to pulse regulation of the order of 10 parts in a million, hard tube

modulators (high current pulses), floating deck grid modulators, HV engineering, crowbar

protection systems, and a reliable and intelligent control and monitoring mechanism for the

transmitter.

In addition, indigenous capability in respect of critical components like high voltage high

frequency transformers, high voltage capacitors and high voltage spark gaps have been

established within the country. Technologies for improving the reliability of compact high voltage

Phase control module X band

C band Rajendra transmitter

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9

The digital approach also helps in managing the RF power utilisation and consequently DC

power optimisation. Depending on the depth of surveillance, an appropriate waveform with

sufficient energy (optimum pulse width) can be automatically programmed, and the waveform duty

is adjusted through the code length to cater for the maximum range selected. Battery powered

systems in use in remote and inaccessible areas have immensely benefitted by this feature that

extends battery life.

DRDO has successfully incorporated digital pulse compression (DPC) technology in two

major radar programs: Indra II (pulse compression version) for the Indian Air Force and BFSR-SR

for the Indian Army.

DRDO has developed programmable-radar-signal processor for

the real-time radar signal processing using high-speed DSPs, and the

software development tool for 3-D Central Acquisition Radar (CAR).

The signal processor for 3-D CAR is a programmable processor

which accepts digitised I/Q radar video signals and processes the data

using complex algorithms for detection and post processing to extract

elevation and plots. All these functions are computation intensive and

are realised in real-time by maintaining the throughput requirement.

The design supports throughput requirement up to 10 MHz. The

architecture of the processor is based on the analog device ADSP-

21060/62 SHARC, commercial-off-the-shelf (COTS) DSP boards as

also on DSP boards designed and developed in-house on multilayer

PCBs (up to 12 layers). Besides, the SHARC-based DSP boards and

high-speed data acquisition modules have also been designed and

developed in-house.

The signal processor technology is a major departure from

conventional approach

and has firmly established

the programmable radar

s i g n a l p r o c e s s i n g

technology for the first time in the country.

Digital IF (intermediate frequency) processing

and pulse compression techniques is being

incorporated in the next generation signal processing

systems which involves digitisation of IF signals at a

very high sampling rate.

Dedicated Signal Processing (DSP)-based Radar Signal Processor

spurious free dynamic range, high order image rejection, and better performance in

offensive electromagnetic environment.

High spectral pure radar source and large dynamic range multichannel receivers

use compact hybrid MIC. DRDO has also developed receivers for different class of

indigenous radar, viz., digital pulse compression radar in L band, airborne surveillance

radar in S band, multifunction phased array radar in C band, CAR in S band, and

BFSR–SR in X band.

The radar sources and receivers technology can be adapted to develop modern

radar systems for defence and civilian use in a short period of time. The technology is

being upgraded using MMICs in radar receivers and direct digital synthesised (DDS)

output driven phase locked loop in radar sources. The new approach will help develop

more compact, lightweight, economical, and reliable sources and receivers.

The pulse compression technique is used in most radar systems as it permits the use of low

peak power waveforms while increasing the energy through wider transmitter pulse widths in order

to realise the desired detection range and to deny the detection by enemy ESM systems. The wide

RF pulse is further modulated in accordance to a code in order to increase bandwidth. The received

echo is processed in a matched filter matched to the characteristics of the code. The fine range

resolution output of the matched filter is a narrow compressed pulse of high instantaneous signal

energy whose width is inversely proportional to the bandwidth. Digital implementation of the

matched filter is now becoming increasingly feasible due to rapid strides in VLSI technology. Digital

realisation provides total flexibility and perfect reproducibility. The matched filter can be dynamically

reconfigured to adapt online to multiplicity of waveforms, code lengths, code patterns and widths of

the transmitted and compressed pulse. A new

dimension of code agility becomes feasible wherein it

is possible to transmit different code patterns on a

packet-to-packet or even pulse-to-pulse basis. This

has an important ECCM advantage as it reduces

vulnerability to smart jammers that use deceptive

techniques to create false targets on the radar screen.

Further, random selection of codes provides for

code diversity, which is an advantage from the EMC

angle. Thus, co-located radar sharing the same

frequency band can still operate with reduced mutual

interference by use of orthogonal code pairs, i.e., those

with lowest cross-correlation.

Radar TechnologyRadar Technology

Digital Pulse Compression

Digital Signal Processing

Radar source and multichannel receiver

CAR SP rack

Digital pulse compression in BFSR signal processorCOTS DSP card

DRDO has achieved a major breakthrough in the area of low power VLSI-based digital signal

processing. A state-of-the-art FPGA-based single board radar signal processor with very low

power consumption has been realised in-house and successfully incorporated in the BFSR-SR

system. The total signal processing function right from I/Q channel A to D, conversion, up to

detection and report formatting, has been realised in a single 20 cm x 20 cm multilayer PCB with a

power consumption of just 3.6 W. The complete design is partitioned into three high-density FPGA

chips of 600 K capacity each. These include, digital pulse compression matched filter with a library

of codes, high resolution doppler filter bank, window function for low spectral side lobes, magnitude

estimation, CFAR, maximum filter seeker, report formatting, configuration register bank, FIFO

interface to radar controller via ISA bus, clutter map generation, electronic countermeasure

environment monitoring, BIST feature, audio doppler extraction, etc.

The VLSI approach has provided a well-established methodology for multimillion-gate

design using matured development tools. This technology has made feasible rapid prototyping of

massive and complex digital systems targeted to just one or more high-density devices thus making

system-on-chip a reality. The biggest advantage of FPGA is the ability to program or reprogram the

chip any number of times. This helps to correct errors and upgrade functions, even when the end

system is in the user’s hand, in the simplest and easiest manner possible provided the external

hardware interfaces and connections are catered for. The use of programmable logic to implement

the signal processor for this class of application is found to be the best choice as it provides a very

high level of integration, extremely low power consumption and flexibility to accommodate

changes, modifications and enhancements.

The radar data processor (RDP)

performs automatic detection and

tracking (ADT) of multiple targets by

processing radar detection plots in real-

time using estimation techniques and

algorithms. The RDP uses the plots

from primary and secondary sensors, to

create and update the tracks, and

provides track-while-scan capability to

search radar. The track information is

then sent to data utilisation centres like

radar consoles for air situation display,

remote data handling centre, target

interception and missile control centre.

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11June 2003

The RDP performs clutter suppression, target classification,

data association, filtering, state prediction, and track management. It

recursively estimates the target attributes like position, and velocity.

To handle the track manoeuvers, methods like variable dimension

filter and interactive multiple model (IMM) filter have been evolved

and optimised. False alarm and clutter are suppressed using

intelligent algorithms, which use escape gate checks and track

confirmation process. The optimum data association logic is used to

resolve the ambiguities in dense target environment. DRDO has

developed RDP for the following radars:

Short and Medium Range Surveillance Radar: The RDP for Air

Force version of Indra radar tracks hundreds of simultaneous aerial

targets and helps perform interception and engagement of enemy targets in autonomous and

netted environment. In the Army version, it provides selected target data to multiple gun control

units. The RDP for CAR performs tracking and sends the 3-D track data to group control centre.

Maritime Surveillance Radar RAWS 03: The RDP for the ship mounted, mobile, Naval radar

RAWS 03 tracks the aerial and sea surface targets. It performs platform motion corrections and

handles the platform motion uncertainty and lags.

Phased Array Radar Rajendra: Rajendra controls the beam positioning sequence through beam

requests for each track at adaptive data rates and performs multifunctional roles like search/

confirm/track/interrogate targets, assign and lock on launchers, and launch/acquire/ track/guide

missiles. The RDP supplies track data to remote group control centre.

SV 2000 Airborne Surveillance Radar: The radar is fitted on a helicopter and tracks aerial/sea

targets in maritime surveillance role. Scanning can be either rotating or sector scan.

Battlefield Surveillance Radar: The land-based targets can have extremely small or no inter scan

displacements. The RDP for BFSR automatically tracks slow and very slow moving targets like

man, motor vehicles and helicopters. The radar antenna performs sector scan with controllable

sweep rates.

Multisensor tracking (MST) and multisensor data fusion (MSDF) are the processes to

integrate the multiple target detection information received from network of heterogeneous sensors

like radar, which may be either co-located or spatially distributed over a large area. The process

produces a unified track database and provides the authentic air space scenario. Such netted

sensor system provides several benefits like synthesised information for higher accuracy,

generation of more specific threat inference, integrated air defense resource management, and

helps in real-time decision making. DRDO has implemented radar-netting solutions for Indian Air

Force and Akash weapon system.

Radar TechnologyRadar Technology

VLSI-Based Programmable Radar Signal Processor

Radar Data Processor

Multisensor Tracking & Data Fusion

RDP display

RDP hardware

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13June 2003

Automated Planar Near-Field Measurement (PNFM) Facility

Spherical Near-Field Measurement (SNFM) Facility

Outdoor Antenna Test Range

Radar Test Platform

Near-Field Test Range (NFTR)

The a

(PNFM) is an indoor antenna evaluation facility

that uses planar near-field measurement technique. It

has an indigenously designed and developed 18 m x

12 m x 10 m temperature-controlled anechoic

chamber lined with pyramidal type microwave

absorbers of various sizes on all the sides. The

absorbers are rearranged in a graded fashion for a

quite zone level better than - 40 dB. The scanning

areas of the planar scanner in X, Y, and Z directions

are 10 m x 6 m x 1 m, respectively. The scanner is

controlled by a PLC system operating either in DOS or

Windows environment.

The facility can be used to measure antennas

measuring up to 7 m wide and 4 m high, and a

frequency range of 1 GHz to 18 GHz. The radar

mounted tracked vehicles can be driven inside for

measurement.

Salient Features

Capability to measure antenna with low side lobe up to - 60 dB

Positioning accuracy of scanner in all 3-axis : 300 microns peak

Scientific Atlanta model 1795 microwave receiver with maximum 5000 data samples output

per second

Stable signal source HP 83640A with frequency range 10 MHz to 40 GHz

Indigenously developed software packages for near-field data acquisition, transformation

and result presentation. The output data can be presented in rectangular, 3-D and contour plot

formats

Receiver frequency range : 0.01 GHz to 140 GHz

Automated Planar Near-Field Measurement Facility

utomated planar near-field measurement

facility

Multisensor Tracking

The 2-D battery surve-0illance radar (BSR) with 360

coverage and a larger

detection range provides

track data to the multi-

function, slewable, 3-D

phased array Rajendra radar.

The multisensor direction

finder in Rajendra processes

the track data from the

phased array radar and the

BSR to identify the targets

reported by both the sensors

and maintains a common

track database. For those

BSR tracks, which are not

being reported by Rajendra

though under it's coverage, target acquisition is initiated with elevation search in the designated

direction. The antenna is skewed in the direction of threat to acquire the targets, which are outside

the covered air space.

Radar Netting for Control & Reporting Centre

The control and reporting centre (CRC) has a network of 2-D, low flying short/medium range

detection, and 3-D ST68 radar. The radar is transportable and heterogeneous surveillance radar,

and performs automatic target tracking locally by radar data processor and sends the track and plot

data to the remotely located CRC through the satellite link. The track data also includes the

associated IFF-based transponder code matches, if available. The sensor data is subjected to time

alignment and stereographic correction at CRC to generate common time and space reference

data. Data fusion is then done for overlapped sensor coverage and updation of centralised track

database. The fusion algorithm uses decisions based on detection probability, sensor accuracy,

track covariance/quality/confidence, etc. and provides fused track state with improved error

covariance and better track maintenance, even under the adverse conditions like screening and

interference/jamming experienced by individual sensor. The CRC with MST software is being used

by the IAF.

DRDO has state-of-the-art antenna evaluation facilities to establish the characterisation, and

determine the performance of the antennas of indigenous radars. Some of these are only one of

their kind in the country and are also being used by the public and private sectors. The facilities are :

Radar TechnologyRadar Technology

Antenna Measurement Facilities

Rajendra–BSR track data fusion

PNFM facility

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Spherical Near-Field Measurement Facility

pherical near-field measurement

facility

Outdoor Antenna Test Range

The automated s

(SNFM) uses SA Model 2022A antenna analyser,

which can be programmed to measure diverse antennas.

A key feature of the SNFM is its capability to perform

measurements in near-field of antenna under test (AUT)

and direct far-field of moderate size antenna. This

enables user to compute near/far-field measurements for

all directions. The SNFM has a computer facility for data

acquisition, transformation and analysis. The facility is

housed in a 18 m x 8 m x 6.5 m shielded microwave

anechoic chamber with all six interior surfaces lined with

pyramidal-shaped absorbing materials to create a quiet

zone of 3 m diameter, reflectivity better than - 50 dB, and

the RF shielding better than 100 dB.

Salient Features

Measurement frequency range : 1 GHz to 18 Ghz

The anechoic chamber houses an optical alignment system and a source tower with

orthomode probe

o oPositional accuracy of the antenna positioner is 0.02 Az, 0.03 roll

oMeasurement accuracy of the SNFM is + 0.5 db in gain, + 1dB at 30 dB in side lobe level, + 0.1

oin beam width, and + 0.1 in null location

The outdoor antenna test range comprises a transmitter

and a receiver located 1.6 km apart from each other. The

transmitter has a parabolic reflector with adjustable height. The

antenna weighing up to one ton mounting facility at the receiver

side on a 3-axis positioner at a height of 21 m from ground can be

tested at the range. A 3-axis positioner can hold a planar antenna

measuring more than 3 m high and 7 m long.

Salient Features

2180SA 100 mw CW power output synthesised sourceo o o

Antenna rotation elevation: - 45 to 90 , upper azimuth: 360 , o

and lower azimuth: +180

The receiving end consists of -100 dBm sensitive 1783 SA

phase and amplitude receiver, and 1580 SA pattern recorder

Near-Field Test Range

ear-field test range

Radar Test Platform

The n (NFTR) is a planar

vertical near-field antenna test facility for testing the

near- and far-field characteristics of the antenna

under test. The range is suitable for testing planar,

high-gain array type antennas operating in the

L band frequency range during development,

production and maintenance stages. However,

many features of the system are upgradeable and

can be utilised for operation at other applications and

frequency ranges.

The NFTR has laser calibration facility for

correction, MIDAS software for data acquisition and

analysis, a beam characterisation facility through

external computer, and a vibration isolated test bed.

Besides, the range also has possible measurement

facility for radiation patterns, back projection on

antenna aperture for diagnostics, gain of the

antenna under test, and pulse mode operation for

L band.

Salient Features

Frequency range : L band for active aperture array; S band for other arrays/antennas

Easily upgradable to other bands

Scan area : 19 m x 8 m in X and Y directions

Side lobe level accuracy : + 3 dB at - 50 dB

Beam pointing accuracy : + 100 micro radians

The testing of radar and its systems call for an unhindered access to airspace free from the

intervening obstructions. The tall buildings and structures makes it difficult to obtain free access to

airspace for systems positioned on ground level. To overcome this problem, DRDO has designed

and developed a 5 m x 7 m radar test platform to hoist radar and test systems weighing up to 50 ton

from ground level to 30 m at a speed of one meter per minute.

The platform is lifted using winch arrangement powered by four 50 hp synchronised motors.

The overall size of the platform is about 11 m x 15 m. The platform rests in level of the adjoining

Radar TechnologyRadar Technology

SNFM facility

ATS

NFTR antenna