Low-Profile Substrate Integrated Choke Rings for GNSS Multipath Mitigation

In this article, a novel technique for the miniaturization of corrugated structures is presented, and multifolded corrugations (MFCs) are introduced. The miniaturization is achieved by implementing multiple folds or slits inside corrugations. The proposed miniaturization technique is modeled using the modal expansion method. An equivalent circuit is extracted, which precisely models the surface impedance of the proposed MFCs. A time-efficient design procedure is presented based on the equivalent circuit model, and a dual-band double-folded substrate integrated choke ring (DFSICR) structure is designed to suppress the propagation of surface waves over the main global navigation satellite system (GNSS) frequency bands: L1 (1573–1587 MHz) and L2 (1215–1240 MHz). The DFSICR demonstrates significant multipath mitigation capabilities, close to that of a classic choke ring, while it eliminates the drawbacks of a conventional choke ring, such as large size, heaviness, costly fabrication, and inability to integrate with printed circuit board (PCB) structures. An example design shows miniaturization of 85% in height and 38% in diameter compared to the conventional choke ring. A prototype is fabricated using FR4 laminates, which demonstrates a weight reduction of more than 90% compared to the classic choke ring. The measurement results confirm the validity of the proposed technique.