Analysis and Design of Ultra-Wideband 3-Way Bagley Power Divider Using Tapered Lines Transformers

An ultra-wideband (UWB) modified 3-way Bagley polygon power divider (BPD) that operates over a frequency range of 2–16？GHz is presented. To achieve the UWB operation, the conventional quarter-wave transformers in the BPD are substituted by two tapered line transformers. For verification purposes, the proposed divider is simulated, fabricated, and measured. The agreement between the full-wave simulation results and the measurement ones validates the design procedure. 1. Introduction Recently, the need for microwave components that have the capability of operating over a wide range of frequencies has motivated many researchers. Thus, many papers that investigate the ultra-wide operation for different microwave devices such as the Wilkinson power dividers (WPDs), branch line couplers (BLCs), and antennas were proposed. In [1], an UWB directional coupler that operates over a frequency range of 3.1–10.6？GHz was presented. To realize such an UWB coupler, two elliptically shaped microstrip lines, which are broadside coupled through an elliptically shaped slot, were used. In [2], a similar approach was used to design a slot-coupled multisection quadrature hybrid coupler for UWB applications. A novel approach for the design of UWB 3？dB couplers, out-of-phase equal-split power dividers, omnidirectional monopole antennas, and directional tapered slot antennas was proposed in [3]. In [4], a novel UWB WPD with modifications on the traditional divider by adding an extra open stub on each branch was proposed. In [5], an UWB WPD that consists of two branches of impedance transformers, each one consisting of two sections of transmission lines with different characteristic impedances and different lengths, was proposed. A modified UWB WPD formed by implementing one delta stub on each branch was proposed in [6]. In [7], and based on the theory presented in [8], a WPD that operates over a frequency range of 2–10.2？GHz was designed by substituting its conventional quarter-wave arms by tapered lines. Three resistors were added along the tapered lines to achieve an acceptable isolation between the output ports. One of the power dividers, which has been a new area of research, is the Bagley polygon power divider (BPD) [9–17]. Compared to other power dividers, such as the Wilkinson power divider, Bagley polygon power divider does not use lumped elements, such as resistors, and can be easily extended to any number of output ports. However, the output ports for such dividers are not matched, and the isolation between them is not as good as that of the Wilkinson power divider. In