This paper proposes a Single Pole Double Throw (SPDT) discrete switch design using switchable radial stub resonators for application of WiMAX and LTE in 3.5 GHz band. Commercialized discrete PIN diodes are used to reconfigure the radial stub resonators between bandstop and allpass response where the theory and circuit operation of the resonators are derived and explained. The implementation of the switchable radial stub resonators in SPDT discrete switch design is discussed together with circuit operation. Measurement result shows the isolation of the SPDT discrete switch is higher than 30 dB in the 3.4 to 3.6 GHz range. The advantages are high and wide isolation bandwidth with minimum number of discrete PIN diodes. © 2013 IEEE.