Sequentially Rotated Circular Antenna Array With Curved PIFA and Series Feed Network

This paper describes the design of a broadside circularly polarized uniform circular array based on curved planar inverted F-antenna elements. Circular polarization (CP) is obtained by exploiting the sequential rotation technique and implementing it with a series feed network. The proposed structure is first introduced, and some geometrical considerations are derived. Second, the array radiation body is designed taking into account the mutual coupling among antenna elements. Third, the series feed network usually employed for four-antenna element arrays is analyzed and extended to three and more than four antennas exploiting the special case of equal power distribution. The array is designed with three-, four-, five-, and six-antenna elements, and dimensions, impedance bandwidth (defined for <inline-formula> <tex-math notation="LaTeX">$S_{11}\leq -10$ </tex-math></inline-formula> dB), axial ratio (AR) bandwidth (<inline-formula> <tex-math notation="LaTeX">$\text {AR}\leq 3$ </tex-math></inline-formula> dB), gain, beamwidth, front-to-back ratio, and cross-polarization level are compared. Arrays with three and five elements are also prototyped to benchmark the numerical analysis results, finding good correspondence.