Efficient Microwave Guide Filters Ultrathin Switchable Microwave FilterBased on Graphene and Slot ArrayThe theoryof ultrathin exchangeable microwave Filter contained of graphene sheet and slotarray is given here, we design an ultrathin active filter utilizing graphene Asthe switchable element, with metal slot arrays enabling a Band-pass feature.When the Fermi energy is adjusted, Rs decreases and graphene act more like aconductive Film which maybe ultimately change the communication between Grapheneand metal slot arrays, the filter consists of a typical periodic cross slot Arraysin a metal plate, above which is a large-area monolayer CVD graphene depositedon silicon oxide covered silicon substrate to offer tenability ofelectromagnetic operation. To clearly test the underlying mechanism of the proposedfilter, the reflection coefficients are depicted in Fig. 4. It can be seen that a strong band-passresonance, attributed to the cross-slot array, occurs at approximately 14.8 GHzin The absence of gate voltages in which graphene is at Dirac point. It is checkedin Fig.
5 (a) that the heavy surface current exists along the edge of crossslot and the electromagnetic response occurs around the slot enabling a passbandof transmission spectra while clearly rather lower density of current isobserved in Fig. 5 (b) when the Fermi level turns to 1.0eV, which point to theresonance has been seriously low by the change of graphene surface resistanceresulting from the application of gate voltages.Fig.5 It is deserved to note that for the switchable filteronly frequencies near the resonance explain sharp transmission decrease at EF =1.0eV?explain an improved provided by the slot layer inspite similar work is not observed in the off-resonant regions.
Models have been establish to explain the circumstance while only a single layer graphene (SLG) sheet isutilized without slot arrays The lowering in transmission of the SLG sheet is far lessthan that of HS at resonance, which reveals the importance of slot arrays intunability and demonstrates the particular changing property of the proposed ultrathin filter at specific frequency Another case we focus on is that structured complementary cross-shapedgraphene patches (CCGP) substitutes the previous continuous graphene layer(CGL) since smaller area of graphene per unit cell in arranging may eliminate the transmission waste due to the material loss. The transmission forthis case is displayed in Fig. 7. The same switching property is completed whenEF=1.0eV because the conductive complementary graphene patch short out the capacitiveresponse associated with the cross slots. And there is an clearly but not large increase in transmission at resonance,indicating a reduction in material loss.
Furthermore, it can also be inferredfrom Fig. 6 and Fig. 7 that the insertion loss at maximum transmission whenEF=0eV may result from the influence of graphene minimum conductivity on the cross slotresonator layer which still influence the band-pass oscillation. In summary, we theoretically and numericallydemonstrate an ultrathin filter based on graphene and slot arrays which can beelectrically switched altering the transmission for microwave band via gate voltages.
By changing the Fermi level of graphene, the band-pass resonance is seriously damped achieving an off state of theswitchable filter.