Abstract Designing and fabricating antennas that exhibit low losses and are compact, lightweight, and highly radiation efficient are challenging in the wireless‐communication field. In this study, we simulated and fabricated microstrip patch antennas using β‐CaSiO 3 low‐temperature co‐fired ceramic (LTCC) as dielectric resonator substrate. Compact ceramics that show good microwave dielectric properties (a relative dielectric constant [ ε r ] of 6.57, high‐quality factor [ Q × f ] of 35 086 GHz [@14.85 GHz], and temperature coefficient of frequency [ τ f ] of −33.56 ppm °C −1 for the optimal composition) were obtained when Li 2 O–CaO–B 2 O 3 –CuO glass was added to β‐CaSiO 3 and sintered at 950°C. The high‐frequency properties of these composite ceramics reveal that the dielectric constant and dielectric loss are stable in the 38−58 and 70−90 GHz ranges, respectively. Furthermore, a circularly polarized antenna fabricated using a CaSiO 3 ‐based ceramic shows a high radiation efficiency (92.04%) and gain (3.35 dBi) at a center frequency of 2.5 GHz. These β‐CaSiO 3 composite ceramics offer promising prospects for high‐frequency use as well as in mobile communication applications. This study provides insight for the development of innovative antennas with new LTCC materials.