EVM Analysis for THz Links under Antenna Misalignment and I/Q Imbalance

We derive an analytical expression of the error vector magnitude (EVM) in terahertz (THz) communication links affected by two performance limiters, namely antenna alignment error and the receiver's in-phase/quadrature imbalance (IQI). Through the sole use of elementary functions, we show how to compute the EVM in closed-form approximately, but accurately and efficiently. Furthermore, we show that antenna alignment errors and IQI can severely degrade the performance of THz communications. Investigations of the special and limiting cases of the regimes pertaining to high signal-to-noise ratio (SNR) and low antenna alignment error variance are carried out, where we also demonstrate the possible separation of the IQI and THz channel effects on the performance of the EVM.