Low Profile Suspended Microstrip Antennas for Wideband Applications

Abstract

In this paper, design of a coplanar capacitive coupled probe fed microstrip antenna suspended above the ground plane is presented. It is demonstrated that the proposed approach can be used for designing suspended microstrip antennas with impedance bandwidth of about 50% and a good gain to operate in various microwave bands. The bandwidth improvement achieved is from the well-known fact that air gap reduces the effective dielectric constant close to unity and increases the thickness of the mixed substrate. However, suspended configurations increase the overall height/volume of the antenna which limits the use of these antennas in compact applications. Therefore, in this work an effort has been made to reduce the overall height (about 55 to 73% keeping adequate impedance bandwidth (> 30%)) of the antenna significantly which is one of the key of design aspects of compact wideband antennas. It is demonstrated that the gain and radiation patterns of the proposed low profile antenna remain nearly unchanged.