LTCC 3-D resonators applied to the design of very compact filters for Q-band applications

We propose a new low-temperature co-fired ceramic (LTCC) U-shaped resonator. The advantages of LTCC technology are employed to design this three-dimensional (3-D) lambda_g/2 resonator. The latter is modeled and optimized by 3-D electromagnetic simulations and is validated by experimental results. In order to validate the coupling between these resonators, a two-pole filter, functioning around 39 GHz, has then been designed and realized with success. Finally, two very compact three-pole bandpass filters have been conceived for a Q-band duplexer design. On the one hand, a filter has been designed around 38 GHz and presents a transmission zero in the upper band. On the other hand, an other filter functioning at 40.7 GHz is presented with a transmission zero in the lower band. Experimental results are in good agreement with theoretical ones