Gain enhancement method of microstrip antennas by dielectric cover, considering bandwidth

The microstrip antenna gain enhancement method which relies on structural resonance by a dielectric cover is referred to as the resonance gain method. However this method is not effective in practical applications which consider bandwidth or require a protective cover of adequate thickness. The gain enhancement of microstrip antennas, considering bandwidth, is investigated using the complex transmission/reflection phenomenon of a wave incident on an antenna covered by a dielectric plate. The electric field distributions are also analyzed. The antenna gain depends on the reflection coefficient at the dielectric cover. When the reflection coefficient on the dielectric cover is 1, referred to as the open condition, the highest amplitude of electric field can reach the radiating patch. The reflection coefficient at the cover depends on its thickness, position and dielectric properties. The open condition is a significant new concept in the design of high-gain antennas and must be applied in designing high-gain antennas with non-negligible bandwidth, making it possible to use a practical dielectric cover of moderate thickness.