Miniaturized Planar Annular Slot Antenna Design Utilizing Shorting Conducting Strip

This letter investigation develops and experimentally explores the miniaturized design for an annular slot utilizing shorting conducting strip. The prototype with the outer and inner radii of the compact annular slot of 16.0 and 12.0 mm, respectively, which is implemented on the 1.6-mm FR-4 substrate with ??_r = 4.4, indicates that the conducting strip offers extended path for the electric current flow from the ground plane to the central patch, achieving 11%-65% size reduction of the fundamental resonant mode. The resonant band shows the broadside radiation pattern with the peak antenna gains of 4.0-5.0 dBi.