Abstract: The transmission line transformer is one of the widely used component in the short wave and the ultra-short wave frequency band. Designed and manufactured components according to the transmission line transformer principle have advantages in compact structure, high power capacity, wide frequency band, low insertion loss and so on. This article presents the techniques to overcome the electrical length limitations of the transmission line for the transmission line transformer devices based on the slow wave principle and the phase compensation technology, and it is possible to employ the transmission line transformer up to the S band. As the example, the theoretical expressions for transmission loss and the high/low input impedance are presented and discussed according to the proposed techniques. Furthermore, the simulation analysis to the 1：4 impedance transformer and power combiner in S band are presented in this paper. The power combiner according to the proposed techniques has been produced and tested. The results of simulation and measured curves indicated that the transmission line transformer devices utilizing the phase compensation technique, together with the slow wave principle, can realize the microwave devices up to the S band.