Microstrip antenna have been versatile used in the area of modern wireless communication, satellite communication, 2G/3G mobile services, marine or land vehicle navigations (GPS), wireless LANs access, many small devices embedded with Bluetooth, UWB, Zigbee, DVB etc. due to their attractive features like low profile, low weight, low cost. Conformability and compatible with MMIC designs. Mostly microstrip antenna suffer from their inherent narrow bandwidth. Many numbers of techniques develop to increase impedance bandwidth. One of the simplest solutions is the utilizations of a thick substrate with low dielectric constant material for a low quality factor. The achieved bandwidth is less than 10% because of the increased inductance generates by feeding probe for a coaxially feed. Introducing the compensating capacitance by loading U-Slot on the patch and enhance bandwidth up to 30%. by using separate aperture coupling structure introduce bandwidth up to 25%. L-Probe and cavity -backed proximity-coupled techniques are able to obtain a bandwidth up to36% and 40% respectively, Stacking patches is another effective technique to enhance bandwidth.
