Miniaturized Cylindrical Open-Ended SIW Cavity Antenna and Its Dual-Band Applications

A cylindrical open-ended substrate-integrated waveguide (SIW) cavity is studied and analyzed in this work. Two orthogonally oriented gaps are used to shrink the dimension of the cylindrical open-ended SIW cavity. Then, the miniaturized cylindrical open-ended SIW cavity is used to construct dual-band antennas. One dual-band antenna is realized by a composite structure that supports two independent modes: they are the half-circular loop mode for the lower band and the half quasi TE11(1/2) mode for the upper band. The other dual-band antenna is an aperture-shared structure: the lower band is related to the miniaturized cylindrical open-ended SIW cavity which works at the quasi TE11(1/2) mode; the upper band is characterized by suspending a concentric slot-loaded circular patch which works at the TM11 patch mode over the empty space of the miniaturized cylindrical open-ended SIW cavity. All modes involved in the two dual-band antennas, the half-circular loop mode, the half quasi TE11(1/2) mode, the quasi TE11(1/2) mode, and TM11 mode, are featured by broadside radiation. The structures of the two dual-band antennas are easy to fabricate by using conventional printed circuit board (PCB) techniques and can be integrated with other planar circuits. Compared to other open-ended cavity antennas, the proposed cylindrical counterpart shows a more compact size and lower profile.