High Gain Antenna using Parasitic Shorted Annular Patch Structure

In this paper, the high gain and broadband antenna operating for SDMB (Satellite Digital Multimedia Broadcasting) system is proposed. The proposed antenna consists of the SAP (Shorted Annular Patch) structure, which inhibits surface-wave and the parasitic SAP element with spacing of 0.25 lambda₀ in order to improve gain, bandwidth and directivity. The RHCP (Right Hand Circular Polarization) is generated by two slits, which are made along the periphery of the circular patch at the diametrically opposite points. The simulated maximum gain of the proposed antenna is 12.6 dBi, which is better 5.22(1) Hi than maximum gain of the conventional microstrip patch antenna. The measured maximum gain is 10.5 dBi. Also, the measured impedance bandwidth ( VSWR les 2 ) of the proposed antenna is 360 MHz (2.488 ~ 2.848 GHz), which is better 300 MHz than the bandwidth of the conventional microstrip patch antenna. The measured HPBW (Half Power Beam Width) of the proposed antenna is 45.8deg, and the measured FBR (Front to Back Ratio) is 15.49 dBi. The 3 dB axial ratio bandwidth is 220 MHz (2.54 ~ 2.76 GHz).