Here is a thread that discusses the common misconception of concurrent multi-beaming advantage of AESA over PESA:
At least for me, that was educational.
052C/052D Class Destroyers
- Thread starter Jeff Head
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Here is a thread that discusses the common misconception of concurrent multi-beaming advantage of AESA over PESA:
At least for me, that was educational.
the Difference between AESA and PESA is whether the individual radiating element in the array have separate or shared signal generators. PESA uses a single or a few signal generator to generate the pulses, which are retarded by different amount as they are sent to different radiating elements so signals transmitted from different eelement are out of phase. AESA uses a separate signal Generator for each transmitting element to generate signals of different phases at different transmitting elements.
PESA can send out multiple beams just like AESA by subdividing the array so radiating elements in each part coordinate in phase to deliver a separate beam, but the number of different frequency it can use is limited so interference between beam is a problem. But because phase adjustment in a PESA is nearly instantaneous it can also send out multiple beams by time share on the same frequency.
PESA can send out multiple beams just like AESA by subdividing the array so radiating elements in each part coordinate in phase to deliver a separate beam, but the number of different frequency it can use is limited so interference between beam is a problem. But because phase adjustment in a PESA is nearly instantaneous it can also send out multiple beams by time share on the same frequency.
Kind of strange he would say this.
"Physics generally dictates the amount of transmit power and gain you can get out of an individual AESA element, so to build a long range system you need many thousands of them. Adding many thousands of receivers on top of that is an incredibly expensive to do, and most real AESA radars do not do this, instead using fewer than 10 receivers and connecting each receiver to a small portion of the full array (called a subarray). "
AESA modules have both a receiver and transmit circuit. The circulator (the round thing you see in the circuit board) routes the signals to the receive or transmit circuit based on the module being in the receive or transmit phase. The transmit circuit has an HPA, while the receive circuit has a LNA. This means literally, every element should have both a receive and transmit.
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According to the reddit poster I just quoted, it is very rare for an AESA radar with 1000s of elements to have a receiver in each element.
He doesn’t explicitly speak of the transmit part of the story, but a receiver is inherently intertwined with the low power transmitter or the waveform generator. These are also commonly reffered to as REX (receiver-exciter).
The way I understood the difference between AESA and PESA is in the location of the HPA and LNA. In AESA these are collocated in the array. The signal first passes through the phaseshifter at low power and is then transmitted.
In PESA, the HPA and LNA are outside the array. The array contains only the phaseshifters. Therefore, in PESA the phaseshifters have to deal with a high power signal on the transmit side.
Can you comment on this?
You addressed it to Richard but let me answer this.
If this is a pulse AESA radar, then each element has both an Rx and Tx phase. Under each element you have circulator that cycles between two circuits, an Tx circuit with an HPA and an Rx circuit with an LNA.
If you are describing an AESA array where the receivers and transmitters are separate, you are probably looking at a CW or FMCW radar.
In PESA, the HPA and LNA are outside of the array, the array contains only the phase shifters. So that's correct.
But how would you describe this? Its an architecture found in some search radars.
You have a module with an HPA and an LNA serving each linear subarray. The amplifiers are not clustered, each servicing each linear subarray.
The modules are set exactly right at the back of the array so it appears they are part of the array.
Or this. 
You are right there. However, I think he meant receiver/exciter not LNA. The way I understood it, signals from LNAs are combined and sent to one of a small number of REX units.
Now that I think about it, if an element has full transmit/receive, processing and waveform generation circuitry then it is a radar in itself. An AESA built out of such elements would constitute a multistatic radar. Don’t you agree?
What's he is saying is something like this.
This means the RX has to leave the module in analog form.
The thing is, not all AESA follow that diagram.
If you looked at the diagram I sent you, the signals are converted from analog to digital right in the module, and exits out of the module in digital form, and when its digital, its headed to the computing backend. Each channel has an D to A converter for the transmit and A to D converter for the receive. So at least for that design, it doesn't apply.
If you look at this module, it has four TX/RX channels, and the signals from four LNA might be combined in the same board. The interface to this module is digital, so anything coming in and out from the back are digital.
Other QTRM designs.
In contrast to the ones above, this module below has a single TX/RX channel. It only has a single 9 pin D shell connector for the transmit but has a coax for the receive. It gets the transmit data in digital but the receive data leaves the module in analog. This might be more what you are talking about. The circulator takes the RX and routes the signal right into where the coax output is. You can see it right there.
Its not the point of being multistatic, in stealth, the design of the body is meant to not send the echoes back to the radiating source. So even if you are multistatic, these stations should not be in the same place as the transmitter. They need to be in a different location. Its not the principle of being multistatic, its the concept that the reciever must be in a different location.
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