Planar antenna in the ISM band with an omnidirectional pattern in the horizontal plane

摘要

A multilayer antenna includes a first layer which is a ground plane and which has a plurality of first clearance holes. A first dielectric layer is positioned over the first layer and a second layer is positioned over the first dielectric layer and has a plurality of quarter wave transformers. A second dielectric layer is positioned over the second layer and a third layer ground plane is positioned over the second dielectric layer and has a plurality of second clearance holes for a feed structure. A third dielectric layer is positioned over the third layer and a fourth layer is positioned over the third dielectric layer and has a cross shape. The first and third layers are coupled together via plated-through holes.