Controlling the resonant modes/bandwidth using graphene strip and isolation enhancement in a two-port THz MIMO DRA

A terahertz (THz) rectangular dielectric resonator (DR) antenna is designed and numerically studied. The analysis is reported with the selection of aspect ratio of DR such that antenna operates with four modes with triple band response. A two port multi–input–multi–output (MIMO) antenna is designed keeping the separation between radiating elements around fifteenth times scaled down of the operating free space wavelength. This antenna configuration provides low value of isolation between the ports. The DRs are loaded with the metal strips which reduces coupling between the radiating elements. Also, loading of the metal strips miniaturizes the higher order modes. The DRs have also been loaded with the graphene strips at the top radiating surface. The resonant modes of antenna can be controlled to provide the triple or wide single band response by appropriate selection of the chemical potential of graphene. Selecting the chemical potential as \(0\, eV\) does not influence the antenna response and antenna continues to provide the triple band response operating at frequencies 2.10–2.33, 2.56–2.65 and 2.77 THz with peak/average isolation of 24.5/20.5 dB, gain \(5.06, 5.81\) and \(2.5\) dBi and radiation efficiency of \(98, 98\) and \(97\%\), respectively. Increasing chemical potential provides the tunability in the resonant frequency of the dominant mode with blueshift. Thus, combined effect of loading of metal and graphene strips leads to merge all the resonance spectra with the chemical potential of \(1\, eV\). This results in a wide impedance bandwidth by merging of all the resonant modes operating in band 2.30–2.86 THz with peak/average isolation 33/20.5, gain 5.27 and radiation efficiency of more than 65%. Thus, a compact two-port THz MIMO antenna can be designed with the ability of controlling the resonant modes to provides the desired response.