Analysis and Design of a Stacked PCBs-Based Quasi-Helix Antenna

In this communication, a new class of circularly polarized (CP) antennas is presented. It is based on the utilization of stacked printed circuit boards (PCBs) in order to realize a quasi-helix. An end-cap disk is used to optimize the axial ratio (AR). Good impedance matching and low AR in a wide frequency band make the proposed antenna an excellent candidate for satellite communication systems and Wi-Fi applications. The structure is composed of eight PCB layers, where each layer is processed using regular single-layer PCB technology. The lowest PCB laminate is used for the feed network, while the higher stacked PCB laminates form the helical radiating element section. Seven microstrip 120° arcs are used on PCB laminates to form a quasi-helix structure, which, with the help of the end-cap disk, can generate electromagnetic CP radiation. A prototype of the proposed antenna for 5.8 GHz WLAN was fabricated and measured to validate the proposed concept. The measured operating bandwidth for $\vert S_{11}\vert < -10$ dB is 33% (5.05–7.05 GHz). The measured 3 dB AR bandwidth covers a frequency band from 5.45 and 6.6 GHz (19.25%). Unidirectional radiation patterns with excellent performance in terms of CP and high front-to-back ratio were obtained over the operating bandwidth.