فهرست نشریات علمی دسترسی آزاد ایران

In this study, a novel dual-band multiple-feed microstrip antenna is introduced for GNSS applications. The proposed antenna has a compact size of 1548 \(mm^2\) and counts as a low-cost, low-profile antenna. The mathematical equations of multiple-feed configuration are driven to analyze circular polarization (\(CP\)) generation and find the effective parameters on \(CP\) value. It is shown that for an n-feed symmetric antenna, the phase shift of \(\frac{2\pi}{n}\) between ports leads to pure \(CP\), regardless of the electrical field pattern. However, if the first feed electric field has equal value in the x and y direction and also 90$^{\circ}$ phase shift, the \(CP\) value is increased. A  symmetric four-feed configuration is employed on the antenna to generate \(CP\). Also, fractal circular rings and perturbing sectors are applied to miniaturize the antenna and improve the \(CP\) value. Numerical simulation shows that all feeding network requirements are met and the phase shift is satisfied at both frequencies by using the coupler technique. Furthermore, results show desirable band width of 48 \(MHz\) and 60 \(MHz\) and high front to back ratio of 16.1 and 14 at \(f_1\)=1.227 \(GHz\) and \(f_2\)=1.575 \(GHz\), respectively. The axial ratio (\(AR\)) beam-width at both frequencies is more than 66$^{\circ}$.