The WI-137-UDR-15 is a laboratory-grade microwave Standard Gain Horn Antenna professionally engineered by Fei Teng Wireless Technology Co., Ltd. (FT-RF) for high-fidelity directional transmission and calibration routines across the 5.85 GHz to 8.2 GHz C-Band spectrum. Striking an exceptional balance between physical volume reduction and high-performance radiation metrics, this premium horn antenna delivers a flat nominal directive gain profile of 15 dBi combined with an exceptionally low maximum V.S.W.R threshold of 1.3 : 1. Precision CNC machined from high-grade structural aluminum alloy in Taiwan, the advanced horn flare geometry establishes a highly uniform radiation footprint, providing symmetrical -3dB beamwidths of 28° in the H-plane and 29° in the E-plane matrix. Equipped with a standardized rectangular square UDR Style Flange layout, this compact 330 g component ensures flawless electromechanical coupling, connects directly into standard WR137 systems without bulky transition interfaces, and safely manages continuous wave power loads up to 800 Watts (CW). Its optimized structural footprint avoids destructive field distortion modes, making it the definitive choice for space-constrained anechoic testing chambers, rigorous EMI/EMC configurations, antenna calibration fields, and mission-critical Signal Defense infrastructure arrays.