Bandwidth Enlargement of a Low-Profile Open-Ring Slot Antenna Based on SIW Structure

In this letter, a compact proximity-fed open-ring slot antenna loaded substrate-integrated waveguide (SIW) structure for bandwidth enlargement is proposed and experimentally validated. The antenna was initially designed for ultrawideband operation and covers the frequency band from 3.8 to 11 GHz with reflection coefficient lower than -10 dB. With the use of stub along with the microstrip feedline, the lower band matching performance is improved. A novel technique for bandwidth enlargement at higher band based on SIW structure is presented. Metallic via-holes through substrate connecting the top and bottom metal plates are strategically aligned to extra widen the antenna bandwidth up to 20 GHz to resonate in the Ku-band. Details of the design methodology and results are presented and discussed.