discone antenna
A Discone antenna, which has similar characteristics to an omnidirectionalantenna, has emerged from biconical antennas. In this antenna, only one visible conical antenna exists, the other is reduced to a plane. Both antennas, the conical and the reduced to plane, consist of six or eight antenna elements. The Discone antenna works like an omnidirectional antenna which concentrates the waves strongly.
The omnidirectional illumination cone is very flat, and the polarization is in the vertical direction, where the beam pattern is kidney-shaped. The antenna gain of Discone antennas is 3 dBi to 4 dBi. The standing wave ratio is frequency dependent and is about 1:1.3, and the antenna impedance is 50 ohms. This changes only slightly over a wide frequency range. Discone antennas are extremely broadband, being used in the VHF and UHF bands between 20 MHz and 1.3 GHz.
In practice, discone antennas are almost exclusively equipped with top radiators, which achieve better values on the transmitter side.