Design of a Dual-Band Planar Sleeve Monopole Antenna With the Substrate-Integrated Coaxial Line Technology

A dual-band sleeve monopole antenna with the substrate-integrated coaxial line (SICL) technology is proposed in this paper. Both the radiation structure and the feeding network are modified from the SICL structure. The antenna provides dual-band operation for LoRa (Long Range Radio) applications covering 433 MHz and 868 MHz bands. This antenna operates as a quarter-wavelength monopole with practical omnidirectional radiation performance for each band. The antenna exhibits a gain of 2.0 dBi at 433 MHz with more than 90% radiation efficiency, and a gain of 1.7 dBi at 868 MHz with more than 90% radiation efficiency. The measured −10 dB impedance bandwidths are from $393 \sim 450$ MHz and $826 \sim 931$ MHz, respectively. A good agreement is observed between the measured and the simulated results, which demonstrates that the proposed scheme can be a possible candidate for LoRa applications.