Ultrawide bandwidth enhancement by using sleeve‐probe feeding in rectangular microstrip antennas

Abstract

This article reports the bandwidth expansion from 1.65 to 8.9 GHz obtained with a new feeding structure featuring a sleeve shell and an L‐probe. Theory analysis and parameter study are performed to reveal the bandwidth expansion mechanism. A prototype antenna is designed and tested based on the study. The antenna's measured results prove the sleeve shell broadens the antenna's impedance bandwidth from 42% to 118%. The measured and simulated results also show the enhancements on the antenna's maximum gain and radiation efficiency in the bandwidth because of the sleeve shell. Besides, it keeps the antenna's radiation patterns intact without requiring additional accommodation space because of the new feed's structural configuration. The combination of the sleeve shell and the L‐probe may be applied to other microstrip antennas for wideband applications.