The Antigen test detects bits of proteins on the surface of the virus.
The Antigen tests detects the proteins and not the actual virus, so it's not as accurate as the PCR test.
Rapid Antigen tests are most accurate when used within a few days of the start of you symptoms.
A nasopharyngeal swab is used to collect the specimen.
Rapid Antigen test results are usually available within an hour of taking the test.