A microstrip dual-band bandpass filter is developed in this article. Using a pair of square open-loops coupled with a symmetric ladder-shaped resonator, frequencies of this filter are operated at 1.57 and 2.45 GHz. The lower resonance frequency is decided by the length of the square resonators, and the higher one is done by the laddershaped resonator. Therefore, both frequency and bandwidth of the upper passband can be controlled flexibly, whereas those of the lower band are fixed. Finally, a filter is fabricated based on the design topology. Measured results have shown very good performance of the filter.ABSTRACT: This article presents multilayer low temperature cofired ceramic (LTCC) millimeter wave filters using trapezoidal resonator with fractal-shaped defection. Operation principle of the resonators is given in detail. The resonators exhibit good electrical performances, compact dimensions and high integration in multilayer dielectric. The LTCC filters implemented in a stripline configuration have a volume of 4.5 Â 2.5 Â 0.6 mm 3 . The performance of the filter is simulated by full-wave electromagnetic simulator-Ansoft HFSS. The proposed filter is fabricated on six layers of a 100-lm LTCC substrate. A fabricated prototype bandpass filter achieves a center frequency of 34.7 GHz, a bandwidth of 26.3%, and an insertion loss of 3 dB that includes input and output transitions, the experimental and simulation results closely correspond to each other. The superior features of the proposed filter make it suitable for use in millimeter wave communication systems and other applications.