To address the limitations of conventional cylindrical piezoelectric transducers in acoustic phased-array look-ahead while-drilling systems — including severe radial-longitudinal coupled vibration, parasitic longitudinal vibration that readily excites drill-collar waves propagating along the drill collar, and insufficient effective radial acoustic radiation, which further degrades the phased array focusing capability and the signal-to-noise ratio of look-ahead echo signals — this article conducts design, numerical simulation, and experimental research on transmitting transducers with dominant radial vibration. Firstly, the radial-longitudinal coupled electromechanical equivalent circuit of radially polarized cylindrical piezoelectric transducers is derived, which reveals the energy distribution law of coupled vibration and the suppression mechanism of parasitic longitudinal vibration. On this basis, a novel structure with circumferentially equally sliced piezoelectric ceramics, filled with buffer materials and adopting alternating excitation is proposed. Through material selection and parameter optimization, PZT-5A is selected as the piezoelectric material, and epoxy resin-II with a thickness of 6 mm is adopted as the filling medium. A finite element coupling model consisting of drill collar, borehole and formation is established for simulation analysis, and prototype samples are fabricated for physical tests. The test results demonstrate that the novel special transducer for while-drilling look-ahead detection achieves higher electro-acoustic conversion efficiency and better downhole environmental suitability within the operating frequency band of 10~15 kHz. Its transmitting voltage response (TVR) increases by 6.38%, the peak radial displacement rises by 185.7%, and the admittance value reaches 2.6 times that of conventional transducers, while the peak longitudinal displacement is reduced by 88%. These results verify that the proposed structure can remarkably weaken the excitation intensity of drill collar wave sources and enhance the effective radial acoustic radiation capacity, effectively suppressing drill collar wave interference induced by longitudinal vibration, and maintaining superior electro-acoustic conversion efficiency and downhole environmental suitability in the 10~15 kHz frequency range. The research outcomes provide core component support for the development of high-performance acoustic phased array look-ahead while-drilling systems.