Ridsdale is confident the club will avoid punishment after referee Mike Dean was hit with a coin during the 2-2 draw with Swansea at Ninian Park but the Football Association of Wales will not comment until they have read Dean's match report.
The Bluebirds chairman, whose side are due to move to their new ground in August, told the Western Mail: "This is a reminder why we need a new stadium. We will have access control at the new stadium and it will be hard to get past security.
"As we become more sophisticated, it will be harder to beat the system. But I was delighted with the co-operation of the fans, CCTV and stewards in identifying the fan involved.
"Our reputation in the dim and distant past wasn't the best. But we have made huge strides and are delighted in the main with what we've done at the club. This incident reminds us, though, that you can never rest on your laurels."