Design Studies of Ultra-Wideband Microstrip Antennas with a Small Capacitive Feed

[摘要] The design of an ultra-wideband microstrip patch antennawith a small coplanar capacitive feed strip is presented. Theproposed rectangular patch antenna provides an impedancebandwidth of nearly 50%, and has stable radiation patternsfor almost all frequencies in the operational band. Resultspresented here show that such wide bandwidths are alsopossible for triangular and semiellipse geometries with asimilar feed arrangement. The proposed feed is a very smallstrip placed very close to the radiator on a substrate abovethe ground plane. Shape of the feed strip can also bedifferent, so long as the area is not changed. Experimentalresults agree with the simulated results. Effects of keydesign parameters such as the air gap between the substrateand the ground plane, the distance between radiator patch andfeed strip, and the dimensions of the feed strip on the inputcharacteristics of the antenna have been investigated anddiscussed. As demonstrated here, the proposed antenna can beredesigned for any frequency in the L-, S-, C-, or X-band. Adesign criterion for the air gap has been empirically obtainedto enable maximum antenna bandwidth for all these operationalfrequencies.

[学科分类] 电子、光学、磁材料