Helical antennas have emerged as a promising solution for biomedical applications, particularly in capsule endoscopy and Wireless Body Area Networks (WBAN), due to their circular polarization, compact structure, and broadband performance. This chapter provides an in-depth exploration of the unique advantages and operational characteristics of helical antennas in biomedical contexts. The chapter starts with the details of WBAN architecture, advantages, and design challenges. Then the focus is shifted to the helical antenna. It categorizes the primary types of helical antennas—monofilar, bifilar, and quadrifilar—and discusses their suitability for specific biomedical scenarios, including applications operating at terahertz frequencies using advanced microstrip antenna substrates. The chapter emphasizes miniaturization techniques essential for the development of in-body antennas, addressing the need for compact and biocompatible designs without compromising performance. Critical design considerations for WBAN-based helical antennas are outlined, including optimal frequency selection to ensure efficient and safe body-centric communication. Techniques for validating antenna designs, such as simulations and experimental prototyping, are also presented. Furthermore, the use of helical antenna arrays is explored as a method to enhance gain, directivity, and overall performance in complex body-worn or implantable systems. The chapter concludes by identifying open research challenges, offering insights into the future of helical antenna development in next-generation biomedical telemetry and diagnostic systems.