Optimizing the Substrate Properties for Increased BandwidthThe easiest way to increase the bandwidth of an MSA is to :1) Print the antenna on a thicker substrate. However, thick substrates tend to trap surface wave modes , especially if the dielectricconstant of the substrate is high . Finally if the substrate is very thick, radiating modes higher than the fundamental will beexcited.2) Decrease the dielectric constant of the substrate. However, this has detrimental effects on antenna size reduction since the resonant length ofan MSA is shorter for higher substrate dielectric constant.. In addition, the directivity of the MSA depends on the dielectric constant of the substrate.3) Stack two patches on top of each other separated by a dielectric substrate or spacers.The application involved two identical circular patches stacked on top of each other. The lowerpatch was fed using a coaxial probe feed, and the top patch was electromagnetically coupled tothe lower one . A stacked circular patch EMC-MSA fed using a coaxial probe.