Abstract: An image element antenna array comprised of slot radiating elements is used for the antenna system for a monopulse tracking system. The image element antenna includes the radiating source disposed between two parallel reflecting planes, one of which is a total reflector and the other a partially reflecting and partially transmitting reflector. The employment of a partially reflecting plane allows for minimizing the number of radiating elements comprising a given antenna array while providing substantially the same gain and pattern activity. The antenna system may be mounted in a missile or the like for transmitting and receiving monopulse energy for steering the missile. The reduced number of radiating elements required reduces the feed network complexity and number with an attended increase in aperture efficiency.