My sirius starmate says "antenna not detected".

The small, gold, circular connector on the bottom of the unit. You can purchase a repair on eBay if the antenna connection has loosened itself from the board.

The problem is likely the actual connection inside the Starmate. It sounds like you have tried alternate antennas, which can only mean the unit itself has an issue. What has likely happened is the antenna jack inside the radio has come loose and is no longer making a connection, in which case it could be repairable. Otherwise there are plenty of other 12v Sirius receivers compatible with the same connections if you are looking to replace the head unit.

Remove the back cover on your radio. The antenna connector is located on the right of the dock connector. Carefully resolder the connections. There are 2 pins (they lead to 3 contacts). Very easy repair, all you need it a fine tip soldering iron and some flux. You can get those for around $15 at wally world.

Check the antenna's connector for your car based antenna. Sometimes the little finger tabs need to be gently pushed back towards the center to make a better connection. Be careful not to move them more than a precision screwdrive blade's width or you might snap it off.

where is the antenna located make sure it is not covered by anything. Also make sure there are no kinks or breaks in the antenna wire

Check your antenna wire to see if it is spliced or cut. If you do not recognize a problem still you can usually get very good help from calling Sirius. They have been good about trouble-shooting and repairs.

I complained strenuously I have not received their reply yet, but they have fixed the problem....on my unit anyway. Today it is now working properly.

try a new antenna...they go bad...

With the antenna plugged in, it may take a minute to aquire the signal. If it takes more than a minute there is a problem with the antenna or the reciever.

with starmate 3 press at same time menu +memo+band with the radio on (with sirius screen only)