In this paper, a reconfigurable standing-wave linear slot array antenna based on substrate integrated waveguide (SIW) technology is presented in 5G frequency band. Both the frequency tuning and the beam shaping can be obtained by incorporating photoconductive switches (PS) in the structure. To this end, a 6-slot SIW array is designed to operate at 29.8 GHz. Then the switches are applied to change the operation frequency to 28 GHz and attain the multibeam functionality. The results obtained by Ansoft HFSS and CST Studio Suite simulators are in close agreement with each other. Furthermore, the analytical results for the radiation patterns show good agreement with the numerical ones.