Bandwidth Enhancement of a Low-Profile Microstrip Antenna Electromagnetically coupled with a Folded Inverted L-shaped Probe

A microstrip antenna (MSA) has a number of useful properties. However, its narrow bandwidth characteristic is disadvantage in applying to practical wireless systems. Some of the conventional techniques for widening bandwidth for the MSA are using thick structures, adding parasitic patches or using electromagnetically coupled feed. In this paper, we proposed a folded inverted L-shaped probe (FILP) to widen the bandwidth of a low-profile MSA by electromagnetically coupled feed. We showed that the FILP which is placed under the patch can increase the value of the input impedance compared to the L-probe, and that the wide bandwidth characteristics of the low-profile MSA is achieved.