The WI-187-UDR-25 is a laboratory-grade microwave Standard Gain Horn Antenna professionally engineered by Fei Teng Wireless Technology Co., Ltd. (FT-RF) for ultra-high performance directional transmission, satellite communications, and anechoic calibration routines across the continuous 3.95 GHz to 5.85 GHz C-Band spectrum. Meticulously optimized to enforce exceptional boresight path stability, this premium horn antenna delivers a commanding nominal directive gain profile of 25 dBi combined with an exceptionally low return reflection max VSWR profile. Precision CNC machined from high-grade structural aluminum alloy in Taiwan, the large-scale horn flare geometry establishes an ultra-focused and symmetric radiation footprint, providing narrow -3dB beamwidths of 12° in both the horizontal and vertical planes. Equipped with a standardized rectangular square UDR Flange layout, this robust 6.3 KG instrument ensures flawless leak-free electromechanical coupling and supports long-range point-to-point microwave links with zero boundary degradation. Its optimized microscopic structural tolerances avoid destructive field distortion modes, rendering it the definitive choice for precision radar calibration benchmarking, high-capacity terrestrial wireless backhaul testing, intensive EMI/EMC profiling, and mission-critical laboratory Signal Integrity verification setups.