An active phase conjugation circuit of retrodirective array which can be used in UHF band (890-960MHz) has been designed. Circuit of the retrodirective array consists of filters, mixers, dividers and other microwave devices. In this paper, microstrip filters and mixers are primarily designed. Divided matching circuit will be designed appropriate on the basis of the antenna element. Filters consist of microstrip coupled lines to conform with microstrip antenna arrays; to suppress the effect of RF input signals to output transmitted signals, selecting the image-rejection mixers. Simulation results of ADS show that all of the designed active devices display good performances.