You betcha...But watch how it is done properly.
Let us take a look at this claim...Now the claimant offered not a shred of credibly technical support for his claim but expect the readers to accept his claim blindly.
I propose to the readers that it is not so easy.
The above is a full size F-22 under EM anechoic chamber testing.
Here is a brief explanation of what is anechoic chamber...
Anechoic chamber - Wikipedia, the free encyclopedia
The main reason for an anechoic chamber is to absorb reflections, audio or EM. Absorb = attenuate. To properly test the fidelity of a speaker, we must eliminate other audio sources. But if we enclose the speaker in a chamber, then we are faced with echoes off the chamber walls when the speaker is active. So we line the walls of the chamber with absorbant to radically reduce any reflections, leaving any audio that we hear or measure to be as true coming from the speaker as possible, usually %99.999 true.
Same idea for testing the RCS figure of the F-22. If we transmit a radar pulse at the body, any reflections off the walls will be statistically insignificant, combine those statistically insignificant signals with the one that actually came off the aircraft and we have as true an RCS figure as currently possible.
The Benefield anechoic facility at Edwards AFB in California is the world's largest EM anechoic testing facility.
Edwards Air Force Base - Media Search
Benefield Anechoic Facility - Wikipedia, the free encyclopedia
From the above sources the readers can see the many types of bodies that can be tested, from small ground vehicles to fighters to bombers.
It is not enough to simply test individual parts of an aircraft in a small EM anechoic chamber, add up the figures and call it good. An aircraft is a complex body and a radar pulse is a wave that will exhibit different behaviors on different surfaces, planar and curves. To know the true RCS of a body, a full body EM test must be performed and because an aircraft is a complex body, it must be tested at different angles. The transmitters (threat sites) can be moved to any location inside the chamber but with the turntable it is unnecessary to move them.
The turntable is about 80ft, or 25 meters, in diameter. Enough to support the wheelbase of any aircraft, even large bombers and cargo. Remember, we are testing a complex body. The turntable can rotate
AIR SUSPENDED bodies at 0.8 deg/sec and platform support bodies at 0.1-0.6 deg/sec, allowing us to change target aspect angle with respect to the transmitters, with 0.1 deg positioning accuracy.
The threat generators can generate surface, sea or airborne type threat signals. At the same time if desired. Like the SR-71 whose true capabilities are still secret, these threat generators can create
SEVERAL HUNDREDS threat signals
SIMULTANEOUSLY. These signals can be stable or modulated, as amplitude or frequency, aka 'agility'. Other forms of signal agility are pulse repetition intervals (PRI) and pulse widths (PW). The more complex the threats the better understanding we have about the body. The threat generators can use all known scan patterns such as raster, conical or circular.
Conical scanning - Wikipedia, the free encyclopedia
The above source is an example of conical scanning which is often used by missiles in their terminal chase mode. Benefield can simulate very complex EM threat scenarios that a US 'stealth' aircraft can face that can affect its RCS. The chamber can be used to test an aircraft's threat warning receiver set (RWR) as to its accuracy in estimating threat angle-of-arrival (AoA).
But wait...There is more...
Once the body has been tested in isolation, it should (not must) be tested with full environmental influences. The above image is of a full size A-12/SR-71 under radar range testing. Notice it is upside down and missing the vertical stabs. There can be many reasons as to why but that is beside the point.
Now the readers can judge for themselves as to whose claim is more credible, the Chinese claim with no supporting evidences that...Or the American claim that it is not so easy and that we invested a lot of money to create our F-22s and F-35s. Of course, the Chinese participants of this forum would say that it is easy but it is a Chinese secret.