A New Compact Size Fractal Based Microstrip Slot Antenna for GPS Applications

A circularly polarized single feed microstrip slot antenna has been introduced in this paper as a candidate for use in GPS applications. The slot structure of the proposed antenna has been created on the radiating patch in two steps. At first, a 45 degree rotated square has been etched at the center of the patch, and then a Sierpinski gasket type of the 3rd iteration occupies the resulting slot. The presented antenna has been fed with a single 50 Ohm probe. The feed position has been allocated in such away to produce the dual orthogonal modes required to produce the circular polarization radiation. The antenna has been designed to resonate at 1.575GHz, L1 GPS band. Finite element simulations have been carried out to evaluate the performance of the modeled antenna using the HFSS v.11 EM simulator, from Ansoft. The resulting antenna has a slotted square patch with side length of about 40 mm. Simulation results show that it possesses impedance and axial ratio bandwidths of about 27 MHz and 22 MHz respectively, which meet the GPS L1 band requirement. Furthermore, the proposed antenna possesses satisfactory circular polarization radiation characteristics and gain. The antenna can be used for a wide variety of communication applications adopting circular polarization.