APG-81 Flawlessly On First Mission Systems Flight of F-35

[seruriermarshal]

Northrop Grumman's APG-81 Radar Sensor Performs Flawlessly On First Mission Systems Flight of Lockheed Martin F-35 Aircraft
BALTIMORE, June 22, 2010 (GLOBE NEWSWIRE) -- Northrop Grumman Corporation's (NYSE:NOC) new APG-81 active electronically scanned array (AESA) radar met and exceeded its performance objectives successfully tracking long-range targets as part of the first mission systems test flights of Lockheed Martin's (NYSE:LMT) F-35 Lightning II BF-4 aircraft.

"Over the last five years, Northrop Grumman has demonstrated unparalleled levels of program success with the APG-81 radar," said Jeff Leavitt, vice president of combat avionics at Northrop Grumman's Electronic Systems sector. "During the F-35 flight, the Northrop Grumman APG-81 radar met and exceeded performance expectations, tracking long range targets at all aspect angles with excellent stability. We look forward to working with Lockheed Martin in demonstrating the APG-81's high resolution synthetic aperture radar (SAR) and other advanced capabilities on subsequent test flights."

In August 2005, the APG-81 radar was flown for the first time aboard Northrop Grumman's BAC 1-11 airborne laboratory. Since then, the radar system has accumulated over 300 flight hours, maturing all five blocks of software. The first radar flight on Lockheed Martin's CATBird avionics test bed aircraft took place in November 2008.

"Northrop Grumman also demonstrated the APG-81's outstanding electronic protection capabilities at Operation Northern Edge in June of last year, far in advance of test program requirements," added Leavitt. "These last five years of comprehensive test bed aircraft flight testing involving the mission critical radar sensor, combined with the recent flight aboard the F-35 aircraft, point to a significant maturity in capability and reduction in risk for the F-35 program."

The Block 0.5 radar software installed in the radar used during the recent F-35 flight test incorporates 60 percent of the radar software to be delivered and provides important capabilities, including long range air-to-air search and track as well as SAR modes, Leavitt noted. The AN/APG-81 radar detected airborne targets before the radars on the F-16 and F-18 chase planes, said Leavitt. Radar and electronic warfare fusion was also observed on the first flights.

"I've flown a number of AESAs and this is the smoothest one out of the box," said David 'Doc' Nelson, Lockheed Martin F-35 test pilot.

Additionally, the F-35 Lightning II aircraft was equipped with Northrop Grumman's revolutionary Electro-Optical Distributed Aperture System, which provides passive missile and aircraft threat detection, as well as infrared day and night vision which is projected directly onto the pilot's helmet visor for a fully spherical view around the aircraft.

Northrop Grumman Corporation is a leading global security company whose 120,000 employees provide innovative systems, products, and solutions in aerospace, electronics, information systems, shipbuilding and technical services to government and commercial customers worldwide. Please visit www.northropgrumman.com for more information.


http://www.irconnect.com/noc/press/page ... l?d=194881

[doge]

I am wondering which thread to post to, so I will post here.
500!! wow
What is the most produced AESA radar for aircraft so far?
https://news.northropgrumman.com/news/r ... ghtning-ii

Northrop Grumman Delivers 500th AN/APG-81 AESA Radar for the F-35 Lightning II
November 07, 2019
BALTIMORE – Nov. 7, 2019 –Northrop Grumman Corporation (NYSE: NOC) has delivered its 500th AN/APG-81 fire control radar for the F-35 Lightning II. The Northrop Grumman AN/APG-81 active electronically scanned array is the cornerstone of the F-35’s advanced sensor suite, providing unparalleled battlespace situational awareness that translates into platform lethality, effectiveness and survivability.

“As a principal member of the Lockheed Martin-led F-35 industry team, our continued investment in facilities and equipment, production enhancements in process and design, and expanded supply chain capability through second sourcing helped reach this milestone,” said Chris Fitzpatrick, director, F-35 programs, Northrop Grumman. “The 500th delivery of this top-of-the-line fighter radar was made possible by our continuous focus on quality and excellence across our company.”

The AN/APG-81 radar has long-range active and passive air-to-air and air-to-ground modes that support a wide range of demanding missions. These modes are complemented by an array of stealth features as well as electronic warfare and intelligence, surveillance and reconnaissance functions.

Northrop Grumman plays a key role in the development, modernization, sustainment and production of the F-35. In addition to producing the AN/APG-81 radar, the company manufactures the center fuselage and wing skins for the aircraft, produces and maintains several sensor systems, avionics, mission systems and mission-planning software, pilot and maintainer training systems courseware, electronic warfare simulation test capability, and low-observable technologies.

[marsavian]

The AN/APG-81 radar has long-range active and passive air-to-air and air-to-ground modes that support a wide range of demanding missions.

So how do the passive modes work ?

[zerion]

The AN/APG-81 radar has long-range active and passive air-to-air and air-to-ground modes that support a wide range of demanding missions.

So how do the passive modes work ?

Fishing with a net.

[Dragon029]

The AN/APG-81 radar has long-range active and passive air-to-air and air-to-ground modes that support a wide range of demanding missions.

So how do the passive modes work ?

Same way they do with an RWR, or when the radar is receiving its own signal; it's just that it'll probably be limited to detecting just X-band emissions and in a forward ~140 degree cone.

[marsavian]

So could the active and passive modes work simultaneously ?

[steve2267]

So could the active and passive modes work simultaneously ?

Uhhh... if you're active... you're by definition not exactly passive...

[marsavian]

What I mean is will the receiver modules identify non APG-81 transmissions when actively transmitting, i.e. act as a permanent RWR.

[Dragon029]

So could the active and passive modes work simultaneously ?

Theoretically yes (even literally simultaneously if you divide the AESA array into multiple independent arrays via software; though realistically you'd just receive signals between emitting), but whether or not the F-35 does it that way I have no idea (I'd lean towards yes though). Hornetfinn would have a better idea of the feasibility.

[wrightwing]

You wouldn't even need to divide the array. You could alternate active and passive modes. Given the speed an AESA can scan it's entire search volume, and that LPI considerations preclude continuous emissions, that leaves plenty of time for passive operation.

[hornetfinn]

Actually all radars continually alternate between active and passive modes. Most of the time these radars are passive just listening to signals, even most high duty cycle AESA radars. Of course they are usually listening to their own transmissions, but modern AESA radar could listen to any signals it can receive within the system bandwidth limits. Of course that's likely about the X-band (8 to 12 GHz) in fighter radars or possibly slightly below and/or above that. GaN based systems can have much wider bandwidth, like 2-18 GHz. Alternating between active and passive modes happens very quickly, but during the transmissions the radar would not be able to listen to signals unless some number of TR modules are dedicated to being passive only. Of course even small number of TR modules would be pretty good for passive operation.

There are many methods which could be used as already mentioned. With F-35 and their very fast MADL data links, they could probably have additional tricks. I could see them switching between active and passive modes in different aircraft continually or some aircraft could remain totally passive most of the time. It might also be possible to use them as multistatic system where one or two aircraft are transmitting and all aircraft are receiving.

[notkent]

Older phased array radars used an TR tube to turn off the receiver while transmitting, this was done to avoid blowing the low noise amps in the receiver.

Transmitting and Receiving at the same time would require some method of cancelling the transmitted waveform that is coupled into the receiver. This would degrade the received signal, it may just be better to limiting receiving while transmitting.

[krorvik]

So could the active and passive modes work simultaneously ?

Sure thing, the last A stands for array - dedicate some to tx, some to rx, or switch rapidly on same element. That's in fact much the point of the *ESA.

Edit: The same element must choose of course - but to the operator, that's not the important part. Abstractions matter.

[hornetfinn]

Good answer krorvik. This is also why digital beamforming in element level is sought after instead of doing beamforming in subarray or array level as it allows maximum flexibility.

Here is very interesting article about these capabilties: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068503/

[notkent]

That is a great article Hornetfinn.

It has a section about using the same elements for xmitt and receive at the same time;

"In practice, a wideband microstrip circulator that may be used in a T/R module does not completely suppress signals travelling in the reverse direction around the circulator. At best, currently available circulators can provide about 30 dB of such suppression between circulator ports

This is sufficient for isolation of the HPA from signals returned by the array element, but not for isolation of the LNA from the HPA output"

circulator - routes the transmit signal from HPA out thru the array, the received signal to the LNA receiver
HPA - High Powered Amp is part of the transmit path
LNA - Low Noise Amp the first amplifier is critical to a good signal to noise ratio for the system