An Antipodal Antenna with Improved Axial Ratio Bandwidth

A circularly polarized (CP) slot antenna is implemented utilizing a Y-shaped radiating strip connected to a quarter wave microstrip feed line for better impedance matching. A parasitic strip, and an antipodal Y-shaped strip are used here to obtain wide axial ratio bandwidth. Utilizing of two optimized spring notches and a rectangular slit on the trapered slot ground plane enhanced circularly polarized radiation. The compact antenna (28 x 28 mm(2); 0.277 lambda(0) x 0.277 lambda(0), lambda(0) is free space wavelength at 2.965 GHz) gives wide measured impedance bandwidth (IBW) from 2.965 to 13.461 GHz, center resonating frequency (f(r)) 8.213 GHz, IBW 127.8% and a total of 10.496 GHz and measured wide CP band of 2.473 GHz (4.209-6.682 GHz, center CP resonating frequency (f(cp)) 5.445 GHz, 45.41%). The maximum measured peak gain of this antenna is 4.672 dBi at 6.5 GHz. Implemented antenna is suitable for some part of "S", "C" and "X" band wireless communication applications.