Design of a Feasible Miniaturized Bandgap Structure in the HF Band

Bandgap structures are applicable for High-Frequency (HF) radars to improve the propagationcharacteristics. The present paper demonstrates a stepwiseprocess to design a feasible bandgap structure at HFfrequencies. At these frequencies, Printed Circuit Board (PCB)materials are impractical for substrate due to large dimensionsof the structures. Thus, soil is replaced as it is the mostavailable dielectric material. The process begins with designinga mushroom-like structure at ۱۰ MHz. Next, the effect ofremoving via on the resonance frequency and bandgap isinvestigated. Subsequently, the metallic patch is replaced by ametallic grid to ease implementation, relieve expenses andreduce RCS. Unfortunately, the metallic grid exhibits a higherresonance frequency and needs to be miniaturized to operate at۱۰ MHz. Miniaturization reduces the width of grid to ۷۵% andkeeps more than ۷۰% of the bandgap. Compared with theconventional mushroom-like structure, the miniaturized gridstructure eases implementation, lowers expenses, downsizesdimensions, significantly reduces RCS and preserves ۶۷% ofbandgap.

Keywords:

HF radars , bandgap structure , miniaturization , EBG