In this paper, a design of planar, compact dual frequency slot array antenna is implemented using substrate integrated waveguide (SIW) cavity backed slot antenna as array element. The proposed design uses a pair of slots placed at the top wall of the cavity to excite higher order hybrid mode along with conventional TE120 mode which helps to create dual resonances. A design of 1×4 array of the proposed SIW cavity backed slot pair is used to achieve dual frequency slot array antenna in planar substrate. The array is fed by SIW power divider. The proposed antenna array resonates at 9.88 GHz and 10.76 GHz with a gain of 11.3 dBi and 11.8 dBi respectively and sidelobe level 12.5 dB below at both resonances. © 2015 IEEE.