Effect of Metal Resistive Losses on the Gain of a THz Planar Spiral Antenna

Full-wave finite-element antenna simulations are carried out between 100 and 700 GHz for a planar square spiral antenna, investigating the effect on the antenna gain of resistive losses in the metal arms. It is found that a large degradation of the gain occurs relative to the same antenna with arms of pure gold. However, the degradation is greatest at low frequencies where the skin depth in the lossy metal is significantly greater than the thickness of the metal arms. As the skin depth approaches the thickness of the arms, the lossymetal antenna gain approaches the gold-arm antenna gain asymptotically.