LTCC Partially-Filled Post-Wall Rectangular-Waveguide Slot Array Antenna in the Millimeter-Wave Band

In the millimeter-wave band, the series-fed array antenna is facing a problem of large transmission loss and narrow bandwidth by using a high-permittivity and large-loss-tangent material. In this paper, an air region is inserted in the half of the height in the LTCC waveguide of er =6.6 and tanδ =0.013 to reduce the transmission loss. The reduction of the equivalent dielectric constant by the air insertion structure enhances both the gain and the bandwidth of the series-fed slot array. The transmission loss of the single-mode rectangular waveguide has been reduced to about 1/6 by using the partially-filled structure in the 60-GHz band. In a onedimensional slot array, the total loss has also been reduced to about 1/7. And the 3 dB-down gain bandwidth has also been increased from 1.3 GHz to 2.3 GHz. key words: waveguide, LTCC, loss, slot array, long-line effect millimeterwave