Substrate integrated waveguide-based ultra-compact self-heptaplexing antenna for IoT connectivity

This paper introduces an innovative design of a substrate-integrated waveguide (SIW)-based self-heptaplexing antenna (SHA). The proposed structure is implemented using a combination of circular and rectangular HM-SIW cavities. Furthermore, the antenna contains seven individual patches on top of the SIW cavity to operate at seven distinct frequencies. The microstrip feeding technique has been used to activate seven distinct ports. All patches are excited through 50-ohm feedlines. The antenna operation is elucidated using an equivalent LC model. To demonstrate its operating principles a self-heptaplexing antenna has been designed to work at 2.45, 3, 3.58, 4, 4.45, 5.2, and 5.88 GHz. The measured realized gain of the proposed antenna at the respective bands is 3.2, 3.85, 3.1, 3.245, 4, 2.98, and 4.5 dBi. The isolation exceeds 20 dB over the entire working bands. The EM-simulated and measured characteristics are in good agreement. Although the suggested antenna has been designed for seven ports and lower frequencies, it has a relatively compact size of 0.28 ${\lambda }_g^2$. The major advantages of the proposed self-heptaplexing antenna include excellent isolation, an ultra-compact design, and good radiation characteristics. The proposed antenna offers a high degree of flexibility. It allows for independent frequency tuning, which makes it suitable for IoT, wireless communication systems, and diverse sub-6 GHz band applications.