Design of an Antenna for INMARSAT Fleet Broadband System Terminal

A novel broadband circularly polarized stacked patch antenna is proposed for INMARSAT Fleet Broadband system terminal applications. The antenna is composed of two corner truncated patches and an unequal power feeding network (UPFN), all of which are printed on the double side of the FR4 substrates. The four output ports of UPFN are connected to the main radiating patch by four probes, while the input port is connected to an SMA connector. Using the proposed unequal power feeding technique, a good impedance matching and low axial ratio (AR) can be achieved. Simulation results are compared with those measured, and a good agreement is obtained. The measurements show that the antenna has an impedance bandwidth (VSWR<1.5) of about 23.4% (1453~1838MHz), a 3dB AR bandwidth of about 25.6% (1360~1760MHz). During the INMARSAT operating band, the VSWR is lower than 1.2, the AR is lower than 1.5dB, and the gain is higher than 9dBi. Therefore, the proposed antenna can be a good candidate for Fleet Broadband FB150 system.