LTCC Oversized Rectangular Waveguide Slot Array Antenna With Air Layers

A partially dielectric-filled structure of low-temperature cofired ceramics (LTCC) oversized rectangular waveguide slot array antenna with air layers both in the radiating and the feeding parts is presented. It has a new structure of partially filled coupling junctions in the feeding waveguide. The efficiency evaluation shows that the air-layer addition reduces the transmission loss both in the radiating and the feeding parts. The gain and bandwidth have been enhanced. The effective dielectric constant is reduced and it broaden the bandwidth of the series-fed feed junctions and the slot array. Using the LTCC with $varepsilon_r = 6.6$ and $tan delta = 0.013$, the dielectric losses of the feeding waveguide are reduced from 4.5 to 0.5 dB. The losses of the radiating waveguide are reduced from 3.7 to 0.45 dB. Experimentally, the gain was shown to increase 5.5 dB. The 3-dB-down bandwidth was improved from 1.4 to 2.1 GHz.