Abstract:Gigahertz Transverse Electro Magnetic (GTEM) transmission cell is widely used in the field of electromagnetic compatibility tests. The transition connector of GTEM transmission cell is closely related with the performance of the transmission cell. The transition connector as a transition of the conversion component between the circular coaxial transmission line and the rectangular coaxial line connects the coaxial transmission line and the main body of the GTEM transfer chamber. If there is a structural discontinuity at the transition connector, it would make the characteristic impedance and the transmission cell mismatch and cause the phenomenon of electromagnetic wave reflection and high-order modes, deteriorating the transmission performance of the transmission room. According to the technical requirements of GTEM transmission cell, it should in principle be a continuous transmission system of impedance. To design the shape of the transition joint's outer surface of the inner conductor and the inner surface of the outer conductor simultaneously, the outer surface of the inner conductor and the outer conductor of the inner surface could smoothly transit, and the transition joint's characteristic impedance could match with the system. To design the connected parts between two ends and standard coaxial line and ax-shaped pieces, the smoothly connected surface, with minimized mutations should be ensured. According to the designed calculation data, the precise three-dimensional model is constructed through the SolidWorks. Three-dimensional model is imported into HFSS to be simulated and tested. So, it provides an effective design method to ensure the constancy of impedance characteristics of the transition joints. The mathematical model could be imported directly into the electromagnetic simulation software for easier further analysis. The inside and outside of the conductor' three-dimensional structure model could be imported into CNC to ensure the accuracy of conductor surface on both sides.