This paper deals with the feasibility of using low-temperature co-fired ceramics (LTCC) as a dielectric substrate in the design of a rectangular dielectric resonator antenna (DRA). The primary objective of this paper is to design an antenna that efficiently uses higher-order modes within a wide frequency range for an increase in efficiency and directivity. LTCC material is chosen for its good dielectric properties and excellent thermal stability, and it is also suitable for multilayer circuits; thus, it is perfectly appropriate for compact designs of high-performance antennas. A substrate-integrated waveguide with a circular slot is used to realize efficient feeding to the resonator and suppress back radiation. The reason for choosing this feeding technique instead of the conventional microstrip feed line is that this offers better performance in reducing back radiation and enhancing the antenna efficiency. This designed antenna realizes a quite high radiation efficiency, greater than 90%, very critical for applications that require significant power transfer and fewer losses. Added to this, the antenna has been carefully designed for broadside radiation patterns with linear polarization, hence making it useful in various wireless communication and sensing applications. It demonstrates that LTCC-based DRAs make possible whole classes of advanced antenna designs and provide a route to accomplish high-efficiency, wideband antennas having excellent directivity with low back radiation.