Comparison Design of X-Band Microstrip Antenna for SAR Application

In this paper presented a comparison of design of the Left Handed Circular Polarization (LHCP) X-band antenna for synthetic Aperture Radar (SAR) application. The purposed of this research is to find the most reliable antenna design for X-band application. The both of the antennas design is implemented a circular-shaped as a patch and truncated by rectangular-shaped. The model 1 design is employed square-ring-slot on the centre of the patch, while model 2 design implemented square-shaped as a slot. The other differences is on their ground-planes, model 1 using circular-ring-slot on the ground plane, then model 2 using plain ground plane. This comparison will provide clear evidence, that between of the two designs which is have more excellent performances. The antenna printed on NPC-H220A substrates with the dielectric constant of 2.17 and the thickness of 1.6 mm and the dissipation factor of 0.0005. Both antennas designed with double substrates, front layer of the first substrate set as a radiation patch, back-side of the first-substrates set a feeding line, then ground plane is at the backside of the second substrate. The Mid-band Frequency of antenna design sets at 9.4 GHz with with low-frequency at 9.0 GHz and higher-frequency at 9.8 GHz. The antenna design with Circular-Ring-Slotted (CRS) on its ground-plane has under -10 dB return loss of 27% (8.2 GHz-10.76 GHz) and the left-handed circular polarized (LHCP) with range bandwidth of axial ratio of 10% (8.8 GHz-9.8 GHz). Whereas, the antenna design with plain ground-plane produced under -10 dB return loss of 35% (8.5 GHz-11.8GHz), then the Circularly polarized characteristic about 12.7% (8.7GHz-9.9GHz). Both of design can achieved gain up to 6 dBic. More detail comparison will explain in the next section.