Resonant cavity antennas (RCA) are superstrate based antennas which are capable of enhancing the directivity of simple sources such as dipoles and patches. These antennas have recently received significant research interest from antenna community owing to their simple design, planar nature and highly directive characteristics but narrowband nature. One of the main research goals associated with RCAs is to enhance their half power directivity bandwidth. In this paper, a very simple RCA design is proposed which improves the half power directivity bandwidth almost 74% more than that exhibited by the conventional RCAs. The proposed antenna has a peak directivity of 20dBi with less than ±0.5dB variation over most of the operating bandwidth. The improved bandwidth of the antenna along with stable directivity, consistent beam quality and sufficiently suppressed sidelobe levels make it highly suitable for wireless point-to-point communication links.