A Compact Frog-Shaped Self-Diplexed MIMO Antenna With SD-HMSIW Technique for WLAN Applications

This communication presents a compact, low-profile, dual-band shielded half-mode substrate integrated waveguide (SD-HMSIW)-based self-diplexed multiple-input multiple-output (MIMO) antenna (SDMA) designed for wireless local area network (WLAN) applications. The MIMO configuration comprises two orthogonally positioned, identical self-diplexing antenna (SDA) elements, forming a slot configuration resembling the anatomy of a frog. Each SDA element features two uniquely shaped modified slots on the top conducting surface of the SD-HMSIW cavity. These SDAs are driven by separate 50- $\Omega $ microstrip feed lines, facilitating radiation at 5.2 and 5.8 GHz with good isolation between the ports. The proposed SDA design method offers exceptional versatility, enabling independent operation at two distinct frequency bands. The overall MIMO configuration of the SDA element enables a compact antenna size of $0.40~\lambda {_{\text {g}}}^{2}$ , with isolation greater than 21 dB between ports and gains of 5.26 and 4.94 dBi at ports resonating at two identical frequencies. The outcomes of MIMO antenna features involving envelope correlation coefficient (ECC), effective diversity gain (EDG), and multiplexing efficiency (MUX) have been evaluated and found to be satisfactory for the proposed SD-HMSIW-based SDMA.