In this report an overview of VLF transmit antennas, with a focus on umbrella antennas, is given. The VLF frequency band, between 3-30 kHz, is used for communication over large distances and with underwater vehicles because of favourable wave propagation conditions. However, the large wavelength implies that the antennas typically are physically large and electrically small. Because of the small electrical size of the VLF-antennas, compared to half wave dipoles, the radiation resistance is small and the negative reactance is large. This cause the antennas to be inherently narrow band and the efficiency is limited for the practically useful band widths. The radiation resistance can be increased somewhat and the reactance reduced if the antenna is capacitively loaded and therefore umbrella antennas are common. The low radiation resistance cause the losses to be significant, e.g. because of limited conductance in the antenna and in the grund plane.