Figure 3
From: Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

Theoretical, simulated and measured Doppler shifts under four different conditions indicated by I to IV.
Four colors correspond to four different experimental conditions: I (Vi = 11 V,Vh = 24 V; the wave incident from the left); II (Vi = 6 V,Vh = 11 V; the wave incident from the right); III (Vi = 11 V,Vh = 24 V; the wave incident from the right); and IV (Vi = 6 V,Vh = 11 V; the wave incident from the left). (TS: theoretical shifts; ES: experimental shifts; SS: simulated shifts; LH: left-handed; RH: right-handed).