This paper presents the design and simulation of a broadband blade antenna for aeronautical and astronautical communication systems, including the Traffic Collision Avoidance System (TCAS), Automatic Dependent Surveillance–Broadcast (ADS-B), and UHF satellite communications (SATCOM). Using CST Studio Suite, a compact blade-type antenna was modeled to operate from 400 MHz to 1.1 GHz, covering both SATCOM (approximately 400–500 MHz) and ADS-B/TCAS (1030–1090 MHz). Performance parameters, such as reflection coefficient, surface current distribution, far-field radiation pattern, gain, and efficiency, were analyzed at multiple frequencies. The results indicate broadband impedance matching, as evidenced by an S11 value below −10 dBi, along with consistent gain ranging from 7.363 dBi to 8.282 dBi throughout the operational frequency band. Compared to conventional aircraft platforms with multiple narrowband antennas, a single wideband blade antenna offers distinct benefits such as reduced aerodynamic drag, lower weight and cabling, simplified certification and maintenance, and improved system integration with reduced electromagnetic interference. By combining multiple services into one compact structure, the proposed design provides an integrated, cost-effective, and aerodynamically efficient solution for modern aircraft and UAV platforms, enhancing the reliability and communication performance across critical missions. We expect the proposed preliminary design blade antenna can contribute to future aircraft technologies.