Loss minimization of LTCC microstrip structure with air-cavities embedment in the dielectric

Abstract

Novel low-loss LTCC microstrip line structures are proposed with air cavities embedded between the strip conductor and the ground plane, and the optimum structure for minimum attenuation is presented in this paper. Measurements of the novel microstrip lambda/4 T-resonator with the air-cavity area of 15% reveal a minimum loss of 0.0084dB/nim and Q-factor of 391 at 15.65 GHz. The dielectric loss is as small as 0.0005 dB/mm at the frequency. This is equivalent to an improvement of a factor of 14 compared to the conventional LTCC microstrip structure. The proposed novel microstrip structure with the embedded air cavities is suited for low-loss LTCC based RF-MCM applications.