This paper presents the design of broadband planar slotted waveguide array (SWA) antenna, excited with novel waveguide feeder network which also functions as broadband impedance matching network. A 4 x 12 narrowband longitudinal shunt slotted waveguide array working at X-band, is designed and integrated with 1:4 waveguide feeder network which offers the broadband impedance matching. Design of such broadband SWA antenna requires computation and matching of active parameters at SWA antenna ports and waveguide output ports. Active reflection coefficients and active normalized admittances have been computed using simulated S-parameters of SWA antenna and waveguide feeder network. Simulation of proposed antenna has been executed using 3D electromagnetic simulator. Prototype of 4 x 12 broadband SWA antenna is also developed and characterized to validate its performance. 6.3% bandwidth of S11 <; -17dB and 24.2dBi boresight gain at 9.6GHz have been achieved in measurement. Comparison of simulated and measured results is presented and found in good agreement.