Omnidirectional antennas broadcast equally in all directions of only ________ cross section(s) of their toroidal (doughnut-shaped) three-dimensional radiation pattern.

The toroidal (doughnut-shaped) 3D radiation pattern of an omnidirectional antenna is uniform only in the single horizontal (azimuthal) plane that bisects the torus, where signal strength is equal in every compass direction. In all other cross-sections - particularly the vertical elevation plane - the pattern is not uniform and tapers toward the antenna's axis, which is why only one cross-section exhibits true 360-degree omnidirectional coverage.

Two uniform cross-sections would imply equal radiation in both a horizontal and a vertical plane simultaneously, which does not match the asymmetric toroidal pattern of a real omnidirectional antenna.

Three cross-sections of uniform radiation would approach near-spherical coverage, which describes an ideal isotropic radiator - a theoretical construct, not a practical omnidirectional antenna.

Four cross-sections of uniform radiation has no correspondence to any recognized antenna radiation pattern model for omnidirectional antennas.