his paper presents a dual-band split-ring structure that provides end-fire radiation characteristics for multi-input multi-output (MIMO) mm-wave 5G applications. The proposed single antenna element consists of a main split-ring resonator (SRR) directly fed using a high impedance microstrip transmission line. A lamda/4 transformer is employed to match the high impedance transmission line with a 50-ohm line. Two symmetric parasitic SRRs are used as directing elements to give end-fire radiation properties for the introduced antenna at the first resonant frequency. The parasitic SRRs are also utilized to produce the second resonant frequency by establishing a capacitive link with the main SRR. The single element antenna radiates at 24.5 and 28.5 GHz. A cross-shaped MIMO structure composed of four elements of the proposed antenna is introduced to improve the isolation of the MIMO system due to its orthogonal |
