"Theoretical modeling, design, assembly, and measurement of a novel integrated phased array radiator are presented. The droopy bowtie turnstile radiator with quad line feed meets challenging radar requirements and uses low cost manufacturing and assembly techniques. This thesis develops the complete theoretical model (antenna, balun, feeding network) of a broadband phased array radiator: the droopy bowtie turnstile radiator. A novel quad line balun feed is developed that provides a low loss, high isolation, and coincident phase-center feeding network for the droopy bowtie. The radiator and feed design combines broadband RF performance and high-isolation dual-linear polarization in a low profile, compact package that enables wide scan volume performance versus frequency. This thesis develops low-cost manufacturing and assembly techniques applied to the droopy bowtie radiator with the quad line feed. The new radiator design would utilize low cost fabrication techniques such as injection molding and 3-D printing, and also leverages automated assembly techniques. Measurement prototypes and array prototypes of droopy bowtie radiators with the quad line feed are developed for L- and X-bands. The measurements demonstrate broadband RF performance in a low profile compact package viable for wide-scale phased array applications."