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TITLE OF THE ARTICLE DESIGN ,SIMULATION AND DEVELOPMENT OF CKT DIAGRAM TO INCREASE ACTIVE RADAR SEEKER’S LOCK-ON TIME

AUTHORS: ILAPAVULURIUMAMAHESHWARRAO,SCIENTIST, ADITYA BHARTI, SCIENTIST, PROGRAMME-AD/RCI,DRDO, KANCHAN BAGH(PO), HYDERABAD-500058, ANDHRA PRADESH,INDIA

ACTIVE RADAR SEEKERS

•: Active Radar Seekers used in INTERCEPTORS plays an

important role in Ballistic missile defence. Although there are

other guidance techniques available for Interception of ballistic

targets

•Homing guidance of the INTERCEPTOR is achieved by

ACTIVE RADAR SEEKERS Which have Several advantages in

the Scenario.

•The ACTIVE RADAR SEEKERS Which are now used have

MICROWAVE TUBES Which gets heated when the

TRANSMITTER is switched on for more time. The Transmitter

lock on time is limited by the transmitter radiation time i.e. only

30 seconds.We have designed a ckt to increase seeker lock-on-

timeto 100 seconds.

CHARACTERISTICS AND ADVANTAGES OF THE DESIGNED SIMULATED DEVELOPED CKT DIAGRAM

•Also the weight of seeker used in present day INTERCEPTORS have a constraint on

the limited RANGE and also Less payload(lowweight warheads).

•In INDIA We are trying to develop SOLID STATESEEKER TRANSMITTERS Which

will be realized in The very near future.How ever we are trying for excellence through

indigenous development in all fields in particular defence research and development

organization through our internal private partners co-operation.

• TECHNOLOGY goes on changing by every time.

•There is a revolution in technology in every field. Technology denied is technology

gained. How ever what existing seekers we have we can’t discard them and say they

are absolete.

•Hence we have designed a circuit diagram having a Y-CIRCULATOR

•Or Power divider to the first input has the seeker tx output.

•pulses.

•THE CKT HAS BEEN SIMULATED ALSO WITH RF AND MICROWAVESOFTWARE ADVANCED

DESIGN SYSTEMS2011 A.

• THE SIMULATED CKTS ARE SHOWN IN THE SLIDES

•THE RESULTS ARE PLOTTEDAS RETURN LOSS AND S11, S12(S-PARAMETERS.

•THE RETURNLOSS AT 17.5 GHZ IS -76DB AND VSWR IS ALMOST 1.0

•The advantage of this circuit is that the LOCK ON TIME OF

SEEKER IS increased to 100 seconds.Even though the

transmitter is on for 30 seconds the echoes start coming

even after the radiation is swiitchedoff.

•Ther is a great need to modify or design the present

existing active radar seekers which use only microwave

tubes and hence there gets a limitation of

activeradarseekers in terms of not only lock -ontime but

also heating effects of microwave tubes used in the

transmitter.

•The second output is directly connected to the SEEKERS SLOTTED

WAVEGUIDE ANTENNA. OR Other wise SEEKER TX.OUTPUT can be directly

connected to the slotted waveguide array antenna inorder not to disturb the

SEEKER. Only the Y-CIRCULATOR 3rd output requires power tapped from any

transmitter part. The Y-CIRCULATOR 3rd output is attenuated and fed to OR –

GATE(ADDER) Or a Power combiner to which a VCXO(VOLTAGE

CONTROLLED CRYSTA OSCILLATOR Whose output similar to seeker tx

output except that the pulse period is 100 seconds.

•The output of OR-GATE(ADDER) OR POWERCOMBINER gets radiated by a

secondary antenna which in this case is an APERTURE COUPLED

MICROSTRIP PATCH ANTENNA.

•We have Simulated this using MATLAB SIMULINK THE DIAGRAM is

included . 2 DISCRETE PULSE GENERATORS having pulse durations 30

seconds and 100 seconds are added by an adder and displayed in 3

oscilloscopes. The First OSCILLOSCOPE has 100 second pulses and 30

second pulses intermixed with each.The second oscilloscope displays 30

seconds pulses the third oscilloscope displays the 100 seconds

DESIGN OF CIRCUIT DIAGRAM FOR INCREASE OF SEEKER LOCKON TIME

Y

SEEKER Tx O/P

CIRCULATOR

1 (i/p)

2 O/P

SEEKER ANTENNA

3 O/P

ATTENUATOR

OR GATE SECONDARY ANTENNA

VCXO

Note: This Circuit can be incorporated in any type of Radar Seeker

ADDITION OF 100 SECONDS & 30 SECONDS PULSES

OSCILLOSCOPE OUT PUT OF 100 SECONDS & 30 SECONDS PULSES

8/10

POWER DIVIDER (LUMPED CKT) DIAGRAM

m1freq=dB(S(1,1))=-28.611

17.49GHz

m2freq=dB(S(1,2))=-3.017

17.50GHz

15.5 16.0 16.5 17.0 17.515.0 18.0

-50

-40

-30

-20

-10

-60

0

freq, GHz

dB

(S(1

,1))

17.49G-28.61

m1

dB

(S(1

,2))

17.50G-3.017

m2

m1freq=dB(S(1,1))=-28.611

17.49GHz

m2freq=dB(S(1,2))=-3.017

17.50GHz

-77

-76.5

-76

-75.5

-75

-74.5

-74

-73.5

-73

14 15 16 17 18 19

Series1

Series2

S11 (dB)S12 (dB)Plots of Power Divider

FREQUENCY(GHz) Vs RETURNLOSS dB

S-PARAMETERS AND RETURNLOSS PLOTS OF LUMPED CKT POWER DIVIDER

Y-Circulator(MicrostripLine)

11 12 13 14 15 16 17 1810 19

-20

-15

-10

-5

-25

0

freq, GHz

dB(S

(1,1

))

Readout

m1

dB(S

(1,2

))

17.24G-3.044

m2

m1freq=dB(S(1,1))=-21.132

17.29GHz

m2freq=dB(S(1,2))=-3.044

17.24GHz

S- Parameters of Y-Circulator

SECONDARY ANTENNA

GEOMETRY OF APERTURE COUPLED MICROSTRIP PATCH ANTENNA

THANK YOU ALL