Battery drain on 2006 Elantra.

I bought a 2006 Elantra approximately a year ago with about 50,000 clicks on it. The car performs great until recently. On 3 different occaisons at about a week apart I go to drive the car but it is completely dead. The keyless entry will not work...the clock is out and the door open ringing sound is gone . When I put the key in the ignition absolutely nothing! Not even a clicking sound. It is a total loss of power. On all 3 occaisons I had my car jumpstarted and it fires up fine. Once the battery is charged the car runs great again until the next time this all happens again. Is it my battery? Is there something seriously wrong with my car? Any help would be much appreciated.