Conformal array antenna design for radio frequency identification (RFID) centralizer activation in extended-reach horizontal wells

To address the challenge of unreliable information transmission and limited installation space in extended-reach horizontal wells, this paper proposes a novel Radio Frequency Identification (RFID) conformal array antenna design for activating variable-diameter centralizers. Based on the constraints of downhole annular dimensions (D1=210 mm and D2=141 mm), an inverted “U”-shaped structure with a width of 34.5 mm was engineered using bending technology. The design utilizes a four-element microstrip patch array with a series-parallel feeding network to achieve high gain and robust impedance matching at 5 GHz. Simulation and experimental results demonstrate that the proposed antenna achieves a significant gain of 7.02 dBi and an effective transmission distance of 0.44 m, which is a 120% improvement over traditional antennas (0.2 m). This work provides a high-performance solution for downhole signal interaction, ensuring reliable control of centralizers in complex extended-reach horizontal well environments.