Compact LTCC millimeter wave bandpass filter with imbedded dielectric resonators

A novel substrate-integrated low-temperature ceramic co-fired (LTCC) millimeter-wave bandpass filter operating in the Ka-band is proposed. The filter is composed of multiple layers of media and metal plane. The dielectric resonators (DRs) with high dielectric constant are embedded in LTCC dielectric cavity excavated in LTCC dielectric. The input/output (I/O) is exploited by the slot on metal plane feed by CPW (Co-Planar Waveguide?structure on the top and bottom metal planes, which make the filter able to be integrated to the other components. Simulations and measurements show that the filter has a center frequency of 35 GHz, a relative bandwidth of about 6%, an insertion loss of 1.25 dB, and a return loss of -15 dB in the passband. The filter has many advantages, such as high selectivity, wide bandwidth, low profile, small volume, and so on, which has high engineering application in 5G communications.