Single-Feed Circularly Polarized Flared-U Fractal Boundary Microstrip Antenna

A new compact Flared-U-type fractal patch antenna is studied for linear and circular polarization (CP). For linear polarization, patch sides are replaced with symmetrical Flared-U fractal curves. By interchanging the edges of a square structure with asymmetrical Flared-U-type fractal curves in two perpendicular directions, two degenerated orthogonal modes are generated for CP emission. To design compact CP antennas, indentation parameters of the Flared-U-type fractal boundary curves are optimized. All the simulations are carried out using finite-element-method-based HFSS electromagnetic simulation tool. Measured results depict that 10-dB return loss and 3-dB axial ratio bandwidths of the presented iteration order (IO) 1 Flared-U CP antenna 2 are 6.17% and 1.8%, respectively, at operating frequencies of 2300 MHz. Obtained results demonstrate that by deploying fractal boundary curves as sides of the square structure, an excellent CP is achieved.