Modification and improvement in the radiation characteristics of a resonance cavity antenna (RCA) have been addressed from a new approach of aperture field synthesis over the superstrate. This concept has been established through a series of systematic studies, which are based on the exciting observations reported very recently by these authors. A process of modification or engineering on the superstrate has been conjectured in view of obtaining reduced sidelobe level (SLL) and/or increased gain. The same has been successfully designed and experimentally demonstrated indicating as much as 10 dB suppression in SLL along with 3 dB improvement in gain compared to its nearest contender. This study promises a potential technique in RCA design along with several attractive features. © 2002-2011 IEEE.