Compact Microstrip Feeding Network for Mobile Base Station Antenna

Most mobile base station antennas constituted from an array of radiating elements fed by a feeding network circuit that satisfy shaping the radiation pattern to meet the desired specifications. In this paper, a feeding network circuit is designed to feed mobile base station antenna array. The number of antenna array elements that satisfies the desired beamwidth and side lobe level is ten. The base station antenna covers the operating band from 0.2 GHz to 2.57 GHz, so it supports GSM380, GSM410, GSM450, GSM480, GSM 710, GSM750, GSM810, GSM850, GSM900, GSM1800 / DCS1800, GSM1900 / PCS1900, UMTS2100, and some used LTE bands. Two feeding circuits are designed one for lower band that extends from 200 MHz to 960 MHz and the other is used for upper band that extends from 1.71 GHz to 2.17 GHz. A compact dual-band microstrip equal Wilkinson power divider looks like zigzag shape yields a size reduction of 45.68 % than the conventional shape is utilized in the feeding network circuit. Two cascaded stages of unequal Wilkinson power divider (UWPD) with certain power division ratios at the out ports are proposed. A three unit hippocampus - shaped defected ground structure (DGS) pattern etched on the ground plane and placed underneath one of the microstrip branch line of both cascaded unequal Wilkinson power divider is used to realize 102 ? lines with a wider width of 1.6 mm. The feeding network is designed and fabricated on FR4 dielectric substrate with dielectric constant of εr = 4.5, loss tangent 0.025 and substrate height of 1.5 mm.