Theoretical and experimental analysis of a circularly polarized notched antenna fed electromagnetically by one microstrip line

A notched antenna electromagnetically coupled with only one microstrip line has been designed to obtain circular polarization. This configuration presents two advantages. First, only one feed line is used, as opposed to usual designs where two microstrip lines are required. This leads to less cumbersome realizations and to simpler antenna arrays. Second, it retains the monolithic concept of integrated circuits: the feed line and the radiation elements are realized with the same technology and are thus simpler to manufacture. The notched antenna has been rigorously and completely analyzed using an integral equation technique. The experimental results are in good agreement with theoretical predictions in X band. The quality of the circular polarization is shown to be very sensitive to the dimension of the notches, and the frequency range for which the ellipticity rate is acceptable is rather small.<>