Do not ignore your citation. If you do it could have all the consequences you are concerned about. Go to court at the date and time indicated on the ticket. Sometimes the cop does not show and the ticket is dismissed. If he does you can cross-examine him regarding the radar. It is legal but the machines must be regularly maintained and in good working order. Ask him about maintenance and if he checked the radar gun that day, the day of your ticket. Then focus on how he knew it was your car that gave the high reading and not a parallel car or even a car going in the other direction. The objection to make if he doesn't know is "no foundation."
Disclaimer: this site is for general educational purposes. My answering your question is based on my knowledge of the common law. Do not assume I know your state’s law or that I am correct. My participation in this forum is not intended to create an attorney client relationship.
Not responding to a mailed ticket will have no consequence. The next step however, will be the State attempting to serve you with process in person. If you get served in person (or find papers on your front door) you must take some action or you may be defaulted and your license may be suspended. Photo radars are objectionable to many people including many judges, so I always advise people to fight them.
It is legal for the state to mail you a photo radar ticket in the mail. However, if you have not mailed back an acknowledgment to the court indicating that you received the ticket, and you have not been served by a process server or police officer, a failure on your part to appear in court should not result in any action on your license. If you do not appear at the scheduled court date, the court may send the ticket out for service by a process server or officer. If that is the case you will have someone attempting to deliver a copy of the ticket to you with a new court date. If successful and you fail to appear for the new court date, you may have a default judgment entered against you (which means you are found responsible for the violation and a fine is imposed) and the court will likely notify the MVD of your failure to appear which will result in a suspension of your driver's license. You may want to closely inspect the ticket you were issued. In some instances a ticket may be issued under the "waste of finite resources" statute. If that is the case the violation does not carry any points with the MVD. In fact the MVD would not be notified of the conviction under this statute.