Dual-band Mushroom Antenna with Two Concentric Circles Composite Vias

Dual-band and low-profile mushroom antenna with vertically-polarized and omnidirectional radiation in the horizontal direction is proposed. The mushroom antenna has multiple vias forming coaxial double ring structure at the center between a ground plane and a metallic patch. The double ring structure of vias has two different parallel resonant frequencies. It is confirmed from the numerical simulation results that the proposed antenna shows omnidirectional radiation pattern at dual-band.