This paper presents the design of a wideband cavity-structure transverse slot antenna based on a substrate integrated waveguide (SIW) for fifth-generation (5G) applications. The antenna is specifically engineered to cover the European 5G frequency range (24.25 – 27.5 GHz). By strategically positioning multiple resonant slots on the bottom metal cladding of the SIW cavity, hybrid modes are generated within the desired frequency band. The characteristics of these modes can be adjusted by altering the slot parameters, resulting in the merging of wideband resonance frequencies. Simulation results demonstrate a bandwidth of 3.3 GHz (13.58%), spanning from 23.5 GHz to 26.8 GHz, with a gain of 10... More >