This work considers the use of dual-reflector antennas for omnidirectional coverage in a LMDS system base station to operate with the distribution of digital TV signals. We investigate the performance of omnidirectional antenna with and without dielectric radome. Numerical simulations based the method of moments are presented to illustrate the usefulness of the omnidirectional antennas to operate in LMDS systems. The analyses are conducted for a 20 per cent bandwidth. It is used a radome with thickness equal to A./2 and relative permittivity equal to 2.08. The analyses intend to demonstrate the radome influence in the antenna behavior across the operation band and to identify the best radome thickness.