Phased Array Radar


1. Phased arrays, an enabling tech for modern radar sys, provide the diversity needed to enhance the performance of the radar sys far beyond the caps of rotating parabolic antenna radars of the past.   Today’s modern phased arrays incorporated active components for high average transmit power, superior low noise performance, unprecedented sensitivity and indep elm lvl phase and amplitude con.   They can op over narrow-bands and produce single and multiple beams.   Multi-functional phased arrays can perform radar, comm and EW ops simultaneously.
Tech Terms
4. Definitions of tech terms that will be used frequently in this lec are att at Anx A.

Basic Radar
5. Basic Pulsed Radar Block Diagram. The most elementary concept of a radar (Fig 1) consists of a pulse modulated transmitter emitting pulses at a certain PRF which defines the min / max range of the radar, a duplexer and a

receiver which displays the tgt loc and range on the presentation unit.

Fig - 1
6. TX. TX generates a short rectangular pulse.   On receipt of pulse duplexer connects the antenna to TX.   Antenna sends out the pulse in the dir in which it is pointing at the time.   At speeds the antenna is still locking in the same dir when the echo returns and it is collected by it.

7. Duplexer. RX is now connected by the duplexer to the antenna and TX is disconnected at the same time.

8. RX. Received pulses are processed in the RX which fwds them to a presentation unit where they can be displayed.   The cycle is now complete and the set is ready for the next pulse transmission.

9. Posn of Tgt. Radar shows the posn of tgt as azimuth and elevation of antenna are known.

PPI       Fig – 2

10. Range. Dist is given by the time taken by the pulse on its fwd and return journey.   Thus with a PRF of 1000 the transmitted pulse length is 1 milli sec, with a listening time of 300 u sec the max range of the radar will be 45 kms. A simulation tool used during...