Design and Improvement Methodology of Super Compact Dual-Band Dual-Circularly Polarized Antennas for UHF/VHF Satellite IoT Communication

This paper proposes a design methodology to obtain a dual-band dual-circularly polarized antenna based on aperture-shared subsequently-fed quadruple inverted-F antennas (QIFAs) with an ultra-miniaturized size of only 100 × 100 × 18 mm3 (0.08λ × 0.08λ × 0.014λ) using folded inverted-F antennas (IFAs) for full-duplex satellite internet-of-things (IoT) communication. Two prototypes are designed with port isolations and radiation gain significantly improved by optimizing the distance and height of the inner and outer two QIFAs. Techniques such as metal stamping and the advanced laser-direct-structuring (LDS) process are used for the fabrication of Prototype-I and -II, respectively. The measured results show that Prototype-I has gains of -5.9/-9.1 dBic, and Prototype-II has improved gains of -5.1/-7.9 dBic at 239/321 MHz, respectively. The proposed antennas with super compact size, dual-band operation, independent polarizations, and acceptable radiation performance could be a useful reference for the design of antennas in satellite communication applications.