Passive Electronically Scanned Array (PESA) and the Active
Electronically Scanned Array (AESA) are basically same in
technology and principles of operation , both systems are capable
of steer its beam Electronically through utilization of Phase
Shifter hence it could be made in fully solid state configuration
where no moving parts required (like APG-77 Radar on F-22 or
Zhuk-AE Radar onboard MiG-35) they're only differs in source of
Radio Frequency (RF) source The AESA uses multiple numbers of
Radiating Elements where each of them have their own Transmitter
and Receiver Module, making the Antenna where those modules located
become "active" because it can Radiate by itself While the PESA
system uses common RF source that usually found in conventional
Radar like Klystrons, Magnetrons and Travelling Wave Tubes (this
one especially, most common in Airborne Application like Fighter
Radar). In Terms of Advantages the AESA system is typically better
than PESA because of following factors : 1.because the Antenna
Elements contain its own Transmitter and Receiver modules and
located Right behind the Radiator, it would have lower or even No
accidental loss , unlike her PESA sister which still require a
connection to be made between its RF source to Radiating elements ,
incidental loss may occur. 2. High fault tolerance, failure of some
modules will not hamper the operation of Radar (typical AESA Radar
may contain 100++ Elements) however the entire device would fail if
the failure occurs in 10% of total module counts.
3.No Single Point Failure , since basically each modules in
active Version contains its own transmitter and Receiver modules,
the passive device however since it still use single Transmitter
device like Traveling Wave tube , failure of the transmitter may
hamper the RADAR operations
Answers by :Xenostrike 06 a.k.a Stealthflanker an Illegally
Banned member from Electrosphere
EDIT- Bit improvements and adding single point failure in
previous answer
Just to help point the above answer at the questions Passive
systems have a single point of failure in its transmit devices
(Travelling Wave Tubes,Wave Guides, Microstrips and Power Dividers
as well as Antenna Feed System) . Active antenna do not have a
single point of failure and a meant to degrades performance
gracefully except probably malfunctions in its tapering systems or
when the beam is steered in very high deflection angle which will
reduce antenna effective Area, increase beamwidth hence reducing
gain an compromise detection range. Active versions are much more
flexible as phase can be varied in each or a groups of Radiating
elements to create different waveforms or beamshapes .
