A T-shaped microstripline -fed printed slot antenna is anlayzed by using the transmission line model(TLM) in this paper. Microstrip-slotline junction is modeled by employing a transformer and the transformer turn ratio is derived empirically. The method is extended to the case of $1 imes2,l imes4$array antennas. Return loss results obtained by using the transmission line model. The maximum measured results and demonstrated the usefulness of the transmission line model. The maximum bandwidths of a single antenna, $1 imes2,l imes4$ array antennas are 28.5%, 47.8%, and 50.9%, respectively, for the VSWR$leq2$. The gain of $1 imes4$ array antenna is 7.97dBi and the beamwidth is about $27^{circ}$.