A stripline T-resonator is designed and implemented in the LTCC substrate for millimeter wave applications. The loss-free air cavities are embedded at both side edges of the conducting strip in order to efficiently reduce the dielectric loss of the stripline structure. The resonator was implemented using 4-layer LTCC dielectrics. The fabricated stripline resonator with air cavities reveals Q-factor of 248 and total loss of 0.035 dB/mm at 34.7 GHz, and that is improved by 108% and 51 %, respectively, compared to the conventional one. The proposed LTCC stripline resonator with the embedded air cavities can meet demands for low-loss millimeter-wave system-on-package (SoP) applications. (c) 2008 Wiley Periodicals, Inc.