Compact, Low-Profile, Bandwidth-Enhanced Substrate Integrated Waveguide Filtenna

• Published in: IEEE antennas and wireless propagation letters 2018-08, Vol.17 (8), p.1552-1556
• Main Authors: Hu, Kun-Zhi, Tang, Ming-Chun, Li, Mei, Ziolkowski, Richard W.
• Format: Article
• Language: English
• Subjects: Band-pass filters; Bandwidth; Bandwidths; Cavity resonators; compact antenna; Couplings; filtenna; Ground plane; Holes; Integrated circuit modeling; low-profile antenna; Metallizing; patch antenna; Patch antennas; substrate integrated waveguide (SIW); Substrate integrated waveguides; Surface impedance; Surface treatment
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2018.2854898

In this letter, a compact, low-profile, bandwidth-enhanced, dual-cavity substrate integrated waveguide (SIW) filtenna is demonstrated. Two SIW cavities are stacked vertically on top of each other. A complementary split-ring resonator slot is etched in the top surface of the uppermost cavity, causing the top surface to act as a patch antenna. The operational impedance bandwidth is significantly enhanced by merging the three resonances that arise from this configuration. One is introduced by the patch, and the other two are inherently generated by the two cavities. A metallized coupling post is introduced from the ground plane through both cavities to the upper surface to excite the fundamental resonant mode of the patch, as well as to electromagnetically couple the two cavities. The optimized filtenna was fabricated by a standard printed circuit board technology and tested. It has a low profile {\text{0.03}}\lambda _{0} and a compact size {\text{0.62}}\,\lambda _{0}\,\times {\text{0.62}}\,\lambda _{0} at its center frequency, f_{0}= {\text{2.95}}\,{\text{ GHz}}. The measured results agree well with their simulated values. They demonstrate a 6.3% fractional bandwidth, a maximum realized gain of 6.73 dBi, a flat gain profile within its passband, and an excellent out-of-band selectivity.