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 degrees 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 vertical bar S-11 vertical bar < -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.