An equivalent network method for the analysis of nonuniform period structures

Abstract

tive reactance contributed from the shorting pin and the w x probe; thus a wider antenna bandwidth could be achieved 4 .The radiation patterns for the compact antenna with l s d are presented in Figure 4. It is seen that the radiation patterns remain broadside. Figure 5 shows the case for the Ž . antenna without slots l s 0 , where the patch resonates at about 1.923 GHz. Similar broadside radiation is also observed. However, because of the increase of the patch surface current component perpendicular to the main excitation diw x rection 3 , the cross-polarization radiation in the H plane is Ž . increased cf. Figures 4 and 5 . On the other hand, the cross-polarization level in the E-plane is still in an acceptable level of less than y20 dB. Finally, it should also be noted that, due to the antenna size reduction, the antenna gain of a compact microstrip antenna will be lower than that of a conventional microstrip antenna operated at the same frew x quency 2 . CONCLUSIONSThe design of a compact meandered circular microstrip antenna with a shorting pin has been described. Experimental results have been presented and discussed. Results indicate that, by combining short-circuiting and meandering of the circular patch, the antenna size can be reduced to be less than 10% that of a conventional circular microstrip antenna operated at the same frequency. This great reduction in antenna size makes it useful for applications where antenna size is a major concern.