Design of probe-fed truncated corner microstrip antennas for Globalstar system

The mobile personal communications are the last generation of satellite communication. Several operators like Globalstar, among others, offer services of global cover. This system provides voice, facsimile, paging, and data transmission to subscribers using LEO (Low Earth Orbit) satellites, in a well-known Walter delta type constellation. Helical structures can be used as antennas on mobile terminals, particularly on cars or trucks, but they tend to be bulky. On the other hand, microstrip antennas are widely used in mobile communication systems, radar systems, and aerospace applications because of their low weight, low profile, and ease manufacturing. For instance, a dual-band patch antenna printed on 3.2 mm thick FR4 material and designed to satisfy both the frequency ranges of the Iridium and Globalstar systems is reported. However, the antenna radiation efficiency which is certainly low is not mentioned. Moreover, its input impedance is overall inductive due to the probe impedance. In this paper, two truncated corner patches printed on CuClad 250 GX microwave laminate, designed to operate as receiving (Rx) and transmitting (Tx) antennas on mobile terminals of Globalstar system, are presented. The design includes a new procedure to compensate the reactive inductance of the antenna input impedance.