Coplanar waveguides have been increasingly used as feeding lines in the design of microstrip antennas, especially when used in the millimeter-wave applications. The reasons are that they have low radiation leakages and that they allow shunt and series connections on the same side of the planar substrate and avoid the use of via holes. In addition, the substrate can be made relatively thick such that the microstrip antenna integrated on the same substrate can be made well-matched with good efficiency and improved bandwidth.Open-end coplanar waveguide fed microstrip antennas have been
studied experimentally