Analysis and design of broadband microstrip patch antenna with a pair of double cross-shaped slots

A novel method of designing broadband microstrip antenna is proposed in this paper. By embedding a pair of Cross-shaped slots placed close to the non-radiating edges of a microstrip patch and adding an air layer between the substrate and the ground, the broadband character can be achieved. What's more, the formulas for calculating the two resonant frequencies have been experimentally deduced. Employing the method and the formulas, a antenna with a pair of double cross-shaped is designed. The measured bandwidth of 15.2% is achieved with small sizes, and the good radiation characteristic for operating frequencies within the impedance bandwidth is also observed.