Effect of the incident angle on the electric near field of a conical probe for plane wave and Gaussian beam illumination.

We consider a simple analytical model for the electric near field of a semi-infinite conical probe and apply it to study the incident angle dependence of the field for the case of side illumination by both the plane wave and the Gaussian beam. The electric near field is shown to peak when approaching the grazing incidence. In some cases, a peak can also occur at an incident angle somewhat below 90 degrees . The results obtained are in qualitative agreement with those for a thin semi-infinite wire and previously published results for the finite-size conical probes.