Tightly Coupled Dipole Array with In-Line Guanella Transformer and Balun

A 3.6:1 bandwidth, efficient, single-pol tightly coupled dipole array antenna fed using an in-line Guanella transformer is presented. The array is designed to operate from 0.57 – 2.05 GHz with radiation and aperture efficiencies of > 88% and > 99%, respectively. $\text{VSWR} < 3$ when scanning in elevation out to ±45° is demonstrated. The dipole elements are integrated with the balun on a two-layer printed circuit board (PCB) with an edge launch SMA coaxial connection per element. This integrated balun design and transformer maintains the simplicity and the low-profile nature of the dipole array. A unit cell design is presented to validate the concept.