2. UWB millimeter wave antenna

Classical antenna as reflector, lens, and horn type antennas have been used in millimeter-wave devices. But for low-cost, these antennas are commercial expensive devices, bulky, heavy and require complex feeding in an array system. In addition, they are very difficult to integrate with solid-state devices [6–9]. However, the microstrip antennas (MPAs) are narrow bandwidth and are large size about half-wavelength structures.
