A novel dual-frequency microstrip antenna with a tuning stub connected to the feedline

In this paper, a novel dual-frequency antenna, characterized by a new feed structure adding a tuning stub to the feedline, is proposed and studied. The new structure can improve the bandwidth characteristic of the antenna at both operating bands. The frequency ratio of the two operating frequencies is tunable in the range of 1.77 to 3.55 by changing the position of the stub. Details of the design and results are presented.