In this dissertation, single-feed circularly polarized (CP) crossed dipoles are incorporated with alternative engineering approaches for profile miniaturization, multiband operation, radiation pattern control, and bandwidth enhancement. A compact crossed dipole is realized with the use of a meander line and an arrowhead-shaped end in each dipole arm. A pair of vacant-quarter printed rings is used in the feeding structure to achieve CP radiation and allow the antenna be matched to a single 50-Ω source directly. For multi-band applications, each dipole arm is divided into multi-branches with different lengths to obtain multiple resonances. These compact radiators can be equipped with different reflectors, including finite planar metallic surface, metallic cavity, and finite artificial magnetic conductor (AMC), to obtain the desired antenna radiation characteristics.
