Discone Antenna

A discone antenna is a version of a biconical antenna in which one of the cones is replaced by a disc. It is usually mounted vertically, with the disc at the top and the cone beneath.

Omnidirectional, vertically polarized and exhibiting unity gain, it is exceptionally wideband, offering a frequency range ratio of up to ~10:1. The radiation pattern in the horizontal plane is quite narrow, making its sensitivity highest in the plane tangent to the Earth's surface. (The term "vertical polarized" implies that the line defining the antenna conductor(s) is placed _perpendicular_ to the Earth's surface, and that "maximum sensitivity" is meaningful only when the transmitting and receiving antennas have similar orientation with respect to the local Earth surface.) The use of the phrase "plane tangent to the Earth's surface" is without definite meaning in this context, and should be ignored.