Antenna design is a critical component in soil temperature and moisture measurement systems utilizing wireless passive surface acoustic wave tags. To enable simultaneous and parallel detection at various depths in the same surface location, a time-division and frequency-division multiple access strategy must be implemented across multiple tags. This paper presents the design of a laminated dual-frequency circularly polarized microstrip antenna alongside a quarter-wave four-way microstrip power divider. The antenna’s distinct patches correspond to specific frequencies and achieve circular polarization through angular truncation. The power divider employs microstrip lines to mitigate issues caused by high-frequency resistance and power dissipation. Simulations and optimizations were conducted using HFSS software, followed by actual fabrication and testing. The results from the vector network analyzer indicate that the antenna’s S₁₁ parameter remains below −10 dB at the central frequencies of 842.5 MHz and 922.5 MHz, with the transmission coefficients of the power divider’s four output ports approximately −6.8 dB. This validates the simulation results and confirms the practicality of both the antenna and the power divider.