I believe a RADAR is where the number sequence is read the same forwards and backwards, like a palindrome.
https://www.mycurrencycollection.com/reference/star-notes/lookup/ http://www.coolserialnumbers.com/FancySerialNumbers.aspx
They make you look twice but there’s nothing special or fancy about them. Definitely not a radar note. These are radar notes. The serial number is the same forward as it is backwards.