Intelligent Signal Coverage Employing Hybrid-Mode Excitation in 5G Spoof Surface Plasmon Polaritons Antennas

Multi-directional signal coverage utilizing simple multi-functional antenna plays a crucial role in 5G smart environment and the massive Internet of Things (IoT). The term “Multifunctionality” refers to an antenna’s ability to control and alter its radiation pattern. Spoof Surface Plasmon Polariton (SPP) antennas are considered simple and cost-effective due to their flexible one-layer configurations, making them a good candidate for smart environment. Different radiation features and signal levels in the spoof SPP antenna employing either separated or combined $k_{-1}$ space harmonic or odd-mode are considered in this paper. Our proposed hybrid-mode antenna combines the above mentioned modes. For this purpose, a phase shift stub (PSS) is proposed for providing required phase delay. Then, the PSS is connected to a sinusoidally impedance-modulated spoof SPP antenna for hybrid-mode excitation. Our antenna supports radiation features of the mentioned modes in separate and hybrid-modes, depending on phase delay value of PSS at the operating frequencies of 26 GHz-30 GHz. Furthermore, a new design guide for odd-mode spoof SPP antennas is introduced in order to decrease side lobes’ level that are more intense in longer antennas. In order to verify the proposed structures’ performance, simulated and measured results of the reconfigurable antenna consisting of diodes and a biasing circuit are presented. The obtained measured results align well with the simulated ones.