Effect of parasitic patch on the bandwidth characteristics of U-slot rectangular microstrip antenna

Since the early 80's, microstrip antennas have received much attention because of their low cost, thin profile and light weight, conformability on curved surface and compatibility with integrated circuitry. However, they suffer from narrow impedance bandwidth. To overcome this drawback, a well known concept is used, which is based on coupling a parasitic patch on the same layer or on another layer, so that bandwidth of around 20% could be obtained. Recently, it has been shown that impedance bandwidth over 30% can be achieved using a single layer probe fed patch antenna loaded with a U-slot [1].