On the performances of simple circularly polarized beam-switching, 3-element and 4-element patch array antennas for mobile satellite broadcasting/communication

Two types of array antennas operating at the 2.6 GHz-band, which can be used for the MSB (mobile satellite broadcasting), are presented. Both are formed of square patches with truncated comers and generate circular polarization. After finding the value of substrate relative permittivity giving the best results, numerical simulations concerning the two antennas were performed. The first array antenna is made of three elements and aims at a reduced size. Its performance is satisfactory in terms of axial ratio in the elevation plane and in terms of minimum gain, but not at low elevation angle. Then a second array, composed of four patches, was analyzed and gave better results. The axial ratio is satisfactory and the minimum gain is better than for the first array, though still under the specification at low elevation angles. Extra simulations revealed that the minimum gain could reach the required 3 dBi at low elevation angles if one of the feeding sources is turned off. This case is still under investigation. As both antennas are interesting, depending on the user, and considering the promising results, it is planned to confirm them by performing measurements.