On the Bandwidth of Monocone Antennas

A method for computing an antenna bandwidth that takes into account the radiation pattern stability over a specified field of view and impedance matching is proposed in this paper. The radiation pattern of a resonant quarter-wave thin monopole is used as a benchmark with respect to which the bandwidth of various monocone antennas are computed and optimized. A simple modification of a classical monocone antenna is proposed and its bandwidth is optimized. It is shown that a modified monocone maintains stable radiation patterns with system gain greater than 0 dBi for 51deg les thetas les 90deg over a 20:1 bandwidth, which is a 94% increase in bandwidth compared to the classical monocone. It is also demonstrated that a 4.6:1 bandwidth with a consistent radiation pattern and system gain greater than 2 dBi is achievable. Theoretical results are supported by measurements and the effects of the finite sized ground plane are also discussed.