Thread by @Doha104p3

A thread on the F-35's radar. (1/20) 🧵

The F-35 (all variants) currently carries the APG-81 radar, and starting at production lot 17 (2026ish), F-35's with a new radar (APG-85) will roll out of the production line.
I'll go over the basic and some stuff on APG-85

The APG-81 is a 3rd gen AESA radar made by Northrop, which derives from the original APG-77 on F-22. It has 1,676 Gallium Arsenide (GaAs) T/RMs. The radar features great LPI characteristics (allowing the aircraft to use the radar w low chance of detection) and long-range

passive and active modes for A-A/A-G,
allowing the aircraft to complete A-A/A-G missions. The APG-81 also serves as the primary emitter for the EW suite (ASQ-239 Barracuda), with the ability to *provide 10 times the effective radiated power of a Prowler* (a dedicated EW platform)

APG-81 operating in X band means the F-35 can perform powerful jamming in the forward area in X band, while in theory, in other band with weaker signals, though there's no reports of that.
Besides jamming, the radar's electronic attack capabilities include creating and showing

false targets to enemy systems, network attacks, and algorithm-packed data streams. The specifics on the F-35's EW and Cyber warfare capabilities are ofc, some of the highly classified stuff, but from what's available, it's highly capable.
web.archive.org/web/2015041310…

In testing within 100 miles, the APG-81 has demonstrated the ability to detect and track 19 targets in 3 seconds and 23 targets in 9 seconds, including targets going towards the opposite direction, while searching for more.

https://x.com/Doha104p3/status/1719002811818467719?t=R8mCV9apSOsTRAseAl5VNQ&s=19

Back in 2009, Lockheed's Catbird aircraft, which was carrying the F-35's entire avionics suite, was able to jam the F-22's radar (the original APG-77).

https://x.com/Doha104p3/status/1726971928265830877?t=rpOz1Qx9uDnbgs-zgWbTLQ&s=19

While APG-81 has great jamming capabilities, its ECCM (jamming resistance) is also Goated. Back in 2010, a joint Northrop and US gov team won the David Packard Excellence in Acquisition Award because of the APG-81's performance against jammer.
investor.northropgrumman.com/news-releases/…

For air to ground, the APG-81 can create high-resolution SAR imageries of targets in the ground from long ranges and automatically identify them, including non emitting ones, allowing the aircraft to engage targets like turned off radars. The targets are identified using MDFs.

Here's a comparison between the SAR image created by a radar on a "legacy" aircraft and APG-81

Providing highly accurate Ground Moving Target Indicator (GMTI) data on SAR maps

APG-81 can also detect and track maritime targets

Being a part of the sensor fusion, if there are targets that have been detected by other things on the aircraft (the EW suite or DAS for example) but not the radar, or vice versa, the fusion will tell the radar or the other sensors where to look based on info already gathered.

This allows the APG-81 to be slaved to that data track and then detect and track the object with a very narrow beam at a longer range while decreasing the chance of interception. This is ofc not unique to APG-81, and same for other radar's when they know where to search for.

The APG-81 working w DAS has also shown the ability to track multiple rocket midflight (Nasa's Terrier Orion).
The yellow shows radar track while the purple shows DAS detection and track. This capability is important for current and future BMD, where the F-35 can send the data

it gathered to platforms like AEGIS equipped DDG or land based A/D batteries. The distance the rockets were detected and tracked from isn't known, but in another testing, DAS has demonstrated the ability to track Falcon 9 from 1,300+ km

As I've mentioned earlier that the APG-81 derives from the F-22's original radar (APG-77). It's worth mentioning that the F-22 (starting in Lot 5) started receiving a new radar (APG-77v1) that uses some of the technology from the APG-81 (the air to ground modes for examples).

As of late 2022, Northrop Grumman delivered over a thousand APG-81, and since then, likely hundreds more. It's unclear whether the upcoming APG-85 will be available to international F-35 buyers, but if not, then the APG-81 line will run for a long time.

There's not much info revealed about the APG-85, but it's pretty much given that it'll do everything the APG-81 can (probably even go beyond those capabilities) and do those things better. While it's not confirmed, it's extremely likely that it'll have Gallium Nitride (GaN) T/RMs

A new radar is one of the 88 upgrade/new capabilities the F-35 will get as part of the Block 4 upgrade. The contract for the first 5 lot has already been awarded, and the JPO was planning on awarding the next 3 as of late last year. Those lots will cover several hundred APG-85s./