The Design of Wideband Phased Array Antenna using Ridged Tapered Slot Antenna In this paper, instead of multilayered notch antenna, the ridged tapered slot antenna (RTSA) is chosen as an element of wideband phased array antenna (PAA) since it has rigid body and can be easily manufactured by mechanical wire-cutting. In addition, because the RTSA is made of conductor, it doesn’t need via-holes which are required to avoid the blind angles out of the operation frequency band.Theses blind angles come from the self resonance of the dielectric material of notch antenna. We developed wide band/wide scan PAA which has a bandwidth of 3:1 and scan volume of plusmn45deg. In order to determine the shape of the RTSA, the active VSWR (AVSWR) of the RTSA was optimized in the numerical waveguide simulator. And then using the E-plane/H-plane simulator, the AVSWR with beam scan angles in E-plane/H-plane are calculated respectively. On the basis of optimized design, numerical analysis of finite arrays was performed by commercial time domain solver. Through the simulation of 10 times 6 quad-element RTSA arrays, the AVSWR at the center element was computed and compared with the measured result. The active element pattern (AEP) of 10 times 6 quad-element RTSA arrays was also computed and had a good agreement with the measured AEP. From the result of the AEP, we can easily predict that 10 times 6 quad-element RTSA arrays have a good beam scanning capabilities