Please Note
The optimum position for an omnidirectional antenna is at the top of the mast as this ensures undisturbed radiation in all horizontal directions.
Mounting of an omnidirectional antenna at the side of a mast imposes some distortion of the radiation pattern as well as the VSWR. The influence is dependent on the distance to the mast and the mast diameter.
Often this effect can be advantageously exploited to create directional patterns when a certain “preferred area” has to be covered by the antenna system.
