Electronic beam tilting of base station antenna: Rotman lens fed

Abstract

A new electronically controlled down-tilt mechanism for wireless communication base station antenna is presented. Its main feature consists of a microwave switch, a symmetrical bootlace lens which is a beam forming device like Rotman (1963) lens, and linearly arrayed antennas. Each beam port of the symmetrical bootlace lens is designed to give a linear phase front across the radiating elements, yielding a radiation spatially summed in a direction normal to the phase front. Furthermore, a few watts small power amplifiers may be inserted between the array ports of the lens and radiating elements to replace the conventional single high power amplifier and heavy cable runs and fixed directive sector antenna with a cost-effective tower-top phased array antenna. These concepts are checked by experimental results.