Hi there,

Possible issues you may consider: fab tolerances, PET dielectric variation, chip bonding parasitics, SBR+ near-field inaccuracies.

1. Simulations assume ideal dielectric constants (ε_r ≈ 2.2–3.0 for PET) and loss tangents (tanδ ≈ 0.001–0.005), but real PET varies by batch (ε_r up to 3.5, tanδ >0.01 due to humidity absorption), shifting resonance by 20–50 MHz and reducing efficiency by 1–3 dB. Al conductivity (σ ≈ 3.8×10^7 S/m) may degrade post-etching (oxidation/surface roughness), increasing ohmic losses by 10–20%. This cuts read range by 20–40%. Calibration studies show adjusting simulated tanδ from 0.02 to 0.12 aligns S11 curves, improving return loss by ~30 dB but shifting frequency. You can measure actual ε_r/tanδ via split-post dielectric resonator or VNA on PET samples. Re-simulate with Monte Carlo tolerances (±10% on params). Test dry vs. humid conditions (PET absorbs ~0.5% moisture).

2. Etching 10 μm Al on PET introduces linewidth errors (±5–10 μm), strap misalignment, or pinholes, detuning impedance (ΔZa >10 Ω) and gain (ΔG 30%, prioritize materials (most common fix). With tweaks, 80–90% sim-measure correlation is achievable (e.g., 8–10 m sim → 6–8 m measured for dipole tags).

Hi amirhosein thank you for you reply, is there any method except the ansys sbr+ to calculate the read range of uhf tag in hfss, that should match the real time vyontic tag formance values, the plotting of graphs , like the example graph that I attached , can we plot like that in hfss I mean x and y axis. Because at the end we have to compare the real time and simulation values. Kindly share some details if get any it might helpful for me.