Broadband sector zone base station antennas

Abstract

With the continuous growth of commercial communications systems, such as cellular communications systems, the need for low-cost antennas has increased. This paper presents printed strip dipole antennas over plane or shaped reflectors that have acceptable impedance matching and radiation patterns over a frequency range of more than 30 percent. The radiating element used for these antennas represents a series-fed array of two closely spaced printed strip dipoles, which have been shown to have broadband capability. We show that such antennas can be designed to have broadband capabilities when placed above a conducting reflector. To achieve a desired beamwidth, the reflector can be shaped, resulting in an antenna that is well-matched and has acceptable radiation patterns over a wide frequency range. Since constructional simplicity and low manufacturing cost are retained, the antenna is very well-suited to being used as a radiating element in sector zone base stations of cellular communications systems. Design examples of broadband antennas with H-plane half-power beamwidths of 120/spl deg/, 90/spl deg/, and 60/spl deg/, suitable for 3-sector, 4-sector, and 6-sector zone use, respectively, are shown.